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Abstract: There is a need, within both geophysical exploration and deep geophysical research, to estimate magnetic basement depth. Forward and inverse modeling studies to map the basement depth are commonly used within petroleum geophysics. To obtain the basement topography, modeling studies are made of the 2D profile data or 3D map data. In this study, a different algorithm was introduced to estimate the magnetic basement depth from map data. The algorithm is based on the analytical solution of exponential equations obtained from Fourier transformation of magnetic data. This algorithm has been tested on synthetic magnetic anomalies originated from multi-prisms. Following encouraging test results, the proposed algorithm was also tested on field data. The depths obtained from the proposed approach were satisfactory in comparison with the depths obtained from seismic survey cross-sections and boreholes. Basic MATLAB code is included in the . [Copyright &y& Elsevier]

Pulverized rocks observed in outcrops near large faults are considered to be products of intense fragmentation occurring during strong earthquakes. However, the exact mechanism and depth of pulverization are controversial. Here we present an analysis of pulverized rocks along an ~930 m interval in a deep borehole in the vicinity of a buried fault. Cuttings of carbonate lithology from below 4980 m host well-preserved sets of dense fractures with a hierarchic branching geometry that was never affected by near-surface processes. Branches are typically symmetric with consistent orientations and hierarchic splitting. The main fractures are spaced at ~0.1 mm, with angular fragments ranging from a few microns to submicrons, indicating further intense localized fragmentation. Splitting of fossils by fractures, in the absence of lateral shear, proves the tensile origin of the fractures. The fracture geometry and density are consistent with dynamic tensile fractures that propagate at critical velocities in laboratory experiments. Thus, these dense branching fractures are the first direct observation that pulverization in fault zones extends to a significant depth and originates from dynamic tensile fracturing. [ABSTRACT FROM AUTHOR]

The Millennium uranium deposit is located within the Athabasca Basin, in northern Saskatchewan, Canada. The deposit is hosted within moderately dipping Paleoproterozoic gneisses that are unconformably overlain by more than 500 m of flat lying, porous Paleoproterozoic to late Mesoproterozoic Athabasca Group sandstones. The deposit is associated with the sandstone-basement unconformity, post-Athabasca structure, and hydrothermal alteration. These features combine to create a complex 3D hydrogeologic setting that presents challenges with respect to mine development, production, and safety. In 2007, as part of a prefeasibility study for potential mine development, a seismic program consisting of a 3D surface survey, vertical seismic profiling, moving source profiling, and side-scan surveys was undertaken to map the complex geology. The geometry and resolution of these different seismic surveys allowed for direct imaging of the geologic targets of interest, regardless of orientation and size. After integration with drill-defined geology, the program successfully imaged the location and character of the unconformity, the post-Athabasca structural setting at camp and deposit scales, and the alteration around the deposit. This information increased the understanding of geotechnical aspects of the geology hosting the deposit, and is currently being used to help minimize risk and costs associated with mine development. Seismic surveys are now viewed as an integral part of risk reduction associated with mining in the Athabasca Basin. [ABSTRACT FROM AUTHOR]

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According to the high uncertainty and vagueness of wellbore stability issue during drilling, the methods of analytical hierarchy process and fuzzy comprehensive evaluation are applied to borehole collapse risk prediction, based on the sufficient analysis on all the factors affecting borehole stability. The analytical hierarchy process method is used to determine the weight coefficients of each factor, and the fuzzy comprehensive evaluation method is taken to establish risk prediction model for borehole collapse. A set of quantitative analyse method is formed to assess the borehole collapse risk, which supplies effective risk control for the potential borehole collapse risk. The model is used in Well YB-22 and the results show that the method is feasible to forecast well collapse risk [ABSTRACT FROM AUTHOR]

Based on influence of porous flow on weak plane model, the authors established a mechanical model of borehole stability for weak plane formation under porous flow and analyzed effect of weak plane on borehole stability under porous flow. The results indicated that porous flow decreased strength of weak plane, enlarged the affecting domains of weak plane for rock mass strength, and worsened borehole instability in weak plane formations. With porous flow increasing, water content of weak plane increases. For the weak plane with DIP < 10°, the borehole is stable; for 10° < DIP < 30°, the borehole is likely unstable when azimuth is close to the direction of maximum stress, and the larger the dip, the worse the borehole stability; for DIP > 30°, it is opposite to the situation of 10° < DIP < 30°. While weak plane formation is next to be saturated, the minimum drilling fluid density for borehole stability does not change with weak plane azimuth and borehole stability is the worst. The mechanical model of borehole stability for weak plane formation under porous flow is applied to a well in Tarim Basin piedmont. [ABSTRACT FROM PUBLISHER]

Abstract: The Pennsylvanian No. 5 Block coal bed in eastern Kentucky is one of several coals considered to be among the splint coals of the Central Appalachians. The coals are generally noted for their inertinite-rich dull lithotypes. Petrographic aspects of the lithologies reveal both fire-derived and degradation-derived inertinites in the assemblages. Fire is not an exclusive contributor to the origin to inertinite macerals; there are many other biological factors, such as the actions and interactions of fungi, bacteria, and insects, which must be considered in the alteration of plant materials to form inertinite macerals. Fungi physically and chemically alter plant tissues to form macerals with a distinct morphology and chemistry different than those formed from fire and other abiological processes. Insects, as secondary sources of wood degradation within a mire, are responsible for physical, such as boreholes from wood-consuming insects, and chemical alteration of plants. Degradation observed in macrinite may be boreholes from wood-consuming insects such as mites. Some inertinite macerals, in particular, macrinite, may be the result of inert fecal pellet conglomerates preserved in the mire. Overall, macerals of the same name can form from multiple and complex biological and abiological processes. [Copyright &y& Elsevier]

3-D geological modeling plays an increasingly important role in Petroleum Geology, Mining Geology and Engineering Geology. The complexity of geological conditions requires different modeling methods in different situations. This paper summarizes the general concept of geological modeling; compares the characteristics of borehole-based modeling, cross-section based modeling and multi-source interactive modeling; analyses key techniques in 3-D geological modeling; and highlights the main difficulties and directions of future studies. [ABSTRACT FROM AUTHOR]

Many problems in reservoir characterization require the formulation and solution of an inverse problem. The definition of the inverse problem is the prediction of reservoir properties from measurements made on the reservoir. The most familiar example of an inverse problem is well-log interpretation. Well logging involves the acquisition of various kinds of data for the purpose of predicting reservoir properties of the earth formations near the borehole. Conventional inverse methods used in the industry today typically involve the constrained minimization of a weighted sum of the squared deviations between a set of measurements and a forward- model equation or equations. The forward-model equations are either empirically or theoretically derived equations. These equations relate the reservoir property to be predicted (e.g., saturation, permeability) to measurements (e.g., resistivity, T2 distributions, porosity). Adjustable parameters in the forward-model equations are determined using a "calibration database" of laboratory measurements made on a suite of representative samples. This traditional methodology suffers from fundamental limitations that stem from the fact that reservoir rocks and fluids are too complex to be described accurately by the simple idealized equations that are used today as forward models. Additionally, the forward models contain adjustable parameters that can vary over a wide range, thereby leading to additional inaccuracies in reservoir properties. Our paper discusses a new model-independent inversion method that overcomes the limitations and inaccuracies of the conventional method. The new inversion method predicts reservoir properties without the need to use idealized model equations or to solve minimization problems. The new method divides the calibration database into input measurements (i.e., used for the predictions) and output measurements (i.e., the reservoir properties to be predicted). The outputs are mapped to the inputs using model-independent mapping functions constructed from Gaussian radial-basis functions (RBFs). The RBF mapping functions are accurate representations of the functional relationship between the database inputs and outputs. The coefficients of the mapping function can be determined uniquely using the database. Once the coefficients are determined, there are no adjustable parameters. The new method is applicable to a wide variety of reservoir-characterization problems. The construction of the mapping functions is presented in detail. We apply the method to a challenging problem in nuclear well logging: accurate predictions of formation thermal neutron-capture cross sections (sigma) from well-logging data. Logs of formation Σ predicted using the conventional regression method and using the new method are compared and discussed. [ABSTRACT FROM AUTHOR]

Abstract: A mudcake formed on the borehole wall between a fluid-filled porous formation and the borehole fluid can affect Stoneley wave propagation used to estimate the formation permeability. The mudcake effect on the permeability dependence of radial oscillations of borehole fluid is investigated in a system with a source generating radial acoustic waves in the borehole and hydrophones (pressure sensors) that record the respective attenuating oscillations of the borehole fluid. The permeability of the porous formation is estimated from theoretical permeability dependence of the attenuation exponent, knowing the time dependence of the exponential attenuation of borehole fluid oscillations. [Copyright &y& Elsevier]

Abstract: A combined approach using two surface geophysical methods (capacity-coupled geoelectrics and ground-penetrating radar) and careful inspection by optical televiewer probes in a network of boreholes (<30m) has been undertaken at an experimental karst site located in the immediate vicinity of the Nerja cave (S. Spain), an important show cave developed in Triassic dolomitic marbles. Our approach has proved helpful in characterizing geometrically and speleologically the vadose zone of these highly heterogeneous environments in that we have been able to identify a considerable number of caves and arrive at an idea of their approximate volume and length. Televiewer logging in the borehole network allowed us to identify a number of karst features: horizontal and vertical openings and cavities, as well as the relative degree of speleothem development. We had previously made a systematic record of the CO2 content of the air inside these boreholes and the results of this earlier study together with the present one have allowed us to further our knowledge of the ventilation patterns in the vadose zone of the research site, which suggest that high CO2 contents (up to 60,000ppm) are directly linked to the degree of karstification. The general geometrical model of karstification in the area suggests a common genesis for the Nerja cave and the numerous cavities revealed during this study. The flows of CO2-rich air and the ventilation patterns in the vadose zone in general seem to be different in the Nerja cave from those in the network of small cavities surrounding it, a circumstance that most likely derives from the fact that the main cave communicates both naturally and artificially with the outside atmosphere. The air-flow regime in the network of boreholes has still to be studied in detail however. [Copyright &y& Elsevier]

The results of electromagnetic sounding of the Earth's crust in the vicinities of the SG-6 and SG-7 superdeep boreholes (Yamal-Nenets Autonomous Okrug) are presented. The studies were conducted in the fields of natural sources (AMT-MTS) and in the field of the Zevs ULF antenna located at a distance of more than 2000 km from the receiver points. In the vicinity of the SG-7 superdeep borehole, where the small industrial noise was observed, the results of inverse problem solution are completely consistent with the electric logging data. The conducting layers have been identified at the depths of 150 m and 1.1 km. The roof of rocks having small electrical conductivity and belonging to the Permian-Triassic trappean complex has been found at the depth of about 7 km. The response of the Zevs signal (the frequency range of 44-182 Hz) has indicated the properties of the upper part of the geoelectrical section better than audiomagnetotelluric sounding for both boreholes. Based on the sounding in the vicinity of the SG-6 superdeep borehole, with the data of the Novosobirsk observatory taken into account, the distribution of resistivity down to about 800 km depth has been obtained. This distribution can serve as additional information in calculation of the temperature and rheological regime of the lithosphere and the upper mantle in the region of Western Siberia. [ABSTRACT FROM AUTHOR]

The results of continuous (September 2010-September 2011) temperature monitoring in the 300-m-deep borehole on Kunashir Island are presented. There were several earthquakes, including the Tohoku one (March 3, 2012, M = 9.0), during the observation period, and they produced a significant coseismic response in the temperature field. The Tohoku earthquake was preceded by a constant decrease in temperature at the depth of 240 m with a mean rate of 0.02 K per month. The coseismic response was manifested in an abrupt (in à day) growth of temperature by 1.2 K. The relationships between the earthquake characteristics (magnitude, epicentral distance) and the amplitude of the coseismic temperature response in the borehole have been estimated. The deformation mechanism of the temperature response to earthquake preparation and implementation processes is suggested. [ABSTRACT FROM AUTHOR]

Measurements of seismoacoustic emissions in boreholes allow researchers to identify fault zones and zones of cracking and rock shattering. These zones are usually identified from the maximal values of seismoacoustic emission. However, the permeability of the identified zones cannot be estimated solely from the seismoacoustic emission data, especially in the case when seismoacoustic emission sources are located in isolation in the vicinity of a borehole. The experiments have shown that dynamically active permeable zones of tectonic failures can be identified based on joint measurements of seismoacoustic emissions and helium concentrations in fluid. [ABSTRACT FROM AUTHOR]

The infiltration of river water into aquifers is of high relevance to drinking-water production and is a key driver of biogeochemical processes in the hyporheic and riparian zone, but the distribution and quantification of the infiltrating water are difficult to determine using conventional hydrological methods (e.g., borehole logging and tracer tests). By time-lapse inverting crosshole ERT (electrical resistivity tomography) monitoring data, we imaged groundwater flow patterns driven by fiver water infiltrating a perialpine gravel aquifer in northeastern Switzerland. This was possible because the electrical resistivity of the infiltrating water changed during rainfall-runoff events. Our time-lapse resistivity models indicated rather complex flow patterns as a result of spatially heterogeneous bank filtration and aquifer heterogeneity. The upper part of the aquifer was most affected by the fiver infiltrate, and the highest groundwater velocities and possible preferential flow occurred at shallow to intermediate depths. Time series of the reconstructed resistivity models matched groundwater electrical resistivity data recorded on borehole loggers in the upper and middle parts of the aquifer, whereas the resistivity models displayed smaller variations and delayed responses with respect to the logging data in the lower part. This study demonstrated that crosshole ERT monitoring of natural electrical resistivity variations of river infiltrate could be used to image and quantity 3D bank filtration and aquifer dynamics at a high spatial resolution. [ABSTRACT FROM AUTHOR]

We introduce a sector-based inversion method to improve the petrophysical interpretation of logging-while-drilling density measurements acquired in high-angle and horizontal wells. The central objective is to reduce shoulder-bed effects on the measurements. This approach is possible because of a recently developed technique to accurately and efficiently simulate borehole density measurements. The inversion-based interpretation method consists of first detecting bed boundaries from short-spacing detector or bottom-quadrant compensated density by calculating their variance, representative of the measurement inflection point, within a sliding window. Subsequently, a correlation algorithm calculates dip and azimuth from the density image. Depth shifts that vary azimuthally and depend on relative dip angle, together with the effective penetration length of each sensor, refine previously selected bed boundaries. Next, the inversion method combines sector-based density measurements acquired at all measurement points along the well trajectory to estimate layer-by-layer densities. In the presence of standoff, the method excludes upper sectors most affected by standoff to reduce inaccuracies due to borehole mud. To verify the reliability and applicability of the inversion method, we first use forward simulations to generate synthetic density images for a model constructed from field data. Results indicate that inversion improves the interpretation of azimuthal density data as it consistently reduces shoulder-bed effects. Inversion results obtained from field measurements are appraised by quantifying the corresponding integrated porosity-meter yielded by inversion methods in comparison to standard techniques that use simple cutoffs on field-processed compensated density. Integrated porosity-meter of inverted synthetic density measurements increases by 4.6% with respect to noninverted field measurements. Also, integrated porosity-meter obtained from inversion results that include only bottom sectors improved by 65.4% with respect to that calculated with field-compensated, bottom-quadrant density measurements. [ABSTRACT FROM AUTHOR]

We present a 3D stochastic inversion method based on the geostatistical approach of cokriging for inversion of magnetic anomaly data on multiple scale parameters using borehole and surface data to limit the resulting solution space. Recovering susceptibilities in 3D magnetic anomaly inversion requires integration of many different data. These data mainly come from different sources with different volume supports (point and block support). The presented algorithm has the capability of inverting data on multiple supports using downscaling and upscaling. Borehole susceptibilities (point support) are up-scaled to block susceptibilities where some of them are selected as constraints. The block constraints are used in magnetic anomaly inversion and, finally, the inverted susceptibilities are downscaled to small prisms. Two modes of application are presented: estimation and simulation. The method is first applied to a synthetic stochastic model. The results of downscaling and upscaling show the ability of the method to invert surface and borehole data simultaneously on multiple scale parameters. The results also clearly show the significant role of borehole data in improving depth resolution. Finally, a case study using susceptibility measurements collected on outcrops and on numerous borehole cores at the Perseverance mine (Quebec, Canada) is presented. The information from the recovered 3D model are useful in analyzing the geology of massive sulfide for the domain under study. It also shows that the addition of constraints at different scales helps in delineating bodies, which would have been missed by only using the magnetic anomaly data. [ABSTRACT FROM AUTHOR]

Dipole sonic log data recorded in a vertical pilot well and the associated production well are analyzed over a 200 x 1100-ft section of a North American gas shale formation. The combination of these two wells enables angular sampling in the vertical direction and over a range of inclination angles from 54° to 90°. Dipole sonic logs from these wells show that the formation's average properties are, to a very good approximation, explained by a transversely isotropic medium with a vertical symmetry axis and with elastic parameters satisfying C13 = C12, but inconsistent with the additional ANNIE relation (C13 =C33-2C55). More importantly, these data clearly show that, at least for fast anisotropic formations such as this gas shale, sonic logs measure group slownesses for propagation with the group angle equal to the borehole inclination angle. Conversely, the data are inconsistent with an interpretation that they measure phase slownesses for propagation with the phase angle equal to the borehole inclination angle. [ABSTRACT FROM AUTHOR]

The experiments on physics and mechanics of borehole hydraulic mining were designed to determine mechanical characteristics of mined oil shale. Oil shale of Nong'an deposit belongs to slightly weathered and relatively complete rocks. Oil shale beds are characterized by a very definite discontinuity in both horizontal bedding orientation and vertical bedding direction. Compressive strength, tensile strength, Poisson's ratio and other data characterizing oil shale beds in different directions in the Nong'an mining site were obtained and compared. The direction of borehole hydraulic mining was determined. The vertical bedding direction to break oil shale was considered to be better because strength in this direction is low, rock mass integrity poor, and the degree of weathering more pronounced. The diameter of borer nozzle, dynamic pressure, maximum caving capacity and other parameters needed for borehole hydraulic mining were selected. [ABSTRACT FROM AUTHOR]

Borehole PRGL1-4 drilled in the upper slope of the Gulf of Lion provides an exceptional record to investigate the impact of late Pleistocene orbitally-driven glacioeustatic sea-level oscillations on the sedimentary outbuilding of a river fed continental margin. High-resolution grainsize and geochemical records supported by oxygen isotope chronostratigraphy allow reinterpreting the last 500 ka upper slope seismostratigraphy of the Gulf of Lion. Five main sequences, stacked during the sea-level lowering phases of the last five glacial-interglacial 100-kyr cycles, form the upper stratigraphic outbuilding of the continental margin. The high sensitivity of the grain-size record down the borehole to sealevel oscillations can be explained by the great width of the Gulf of Lion continental shelf. Sea level driven changes in accommodation space over the shelf cyclically modified the depositional mode of the entire margin. PRGL1-4 data also illustrate the imprint of sea-level oscillations at millennial time-scale, as shown for Marine Isotopic Stage 3, and provide unambiguous evidence of relative high sea-levels at the onset of each Dansgaard-Oeschger Greenland warm interstadial. The PRGL1-4 grain-size record represents the first evidence for a one-to-one coupling of millennial time-scale sealevel oscillations associated with each Dansgaard-Oeschger cycle. [ABSTRACT FROM AUTHOR]

The investigation of observed borehole temperatures has proved to be a valuable tool for the reconstruction of ground surface temperature histories. However, there are still many open questions concerning the significance and accuracy of the reconstructions from these data. In particular, the temperature signal of the warming after the Last Glacial Maximum is still present in borehole temperature profiles. It is shown here that this signal also influences the relatively shallow boreholes used in current paleoclimate inversions to estimate temperature changes in the last centuries by producing errors in the determination of the steady state geothermal gradient. However, the impact on estimates of past temperature changes is weaker. For deeper boreholes, the curvature of the long-term signal is significant. A correction based on simple assumptions about glacial-interglacial temperature changes shows promising results, improving the extraction of millennial scale signals. The same procedure may help when comparing observed borehole temperature profiles with the results from numerical climate models. [ABSTRACT FROM AUTHOR]

Abstract: This study presents an integrated approach for field tests and numerical investigations to assess the risk of coal bumps. This approach produces a stress-relief technology using boreholes to mitigate risk during the extraction of an island longwall panel. The field tests were conducted in an island longwall panel in the Tangshan coal mine in the city of Tangshan, China. In these tests, roadway roof displacement and electromagnetic radiation (EMR) of roadways in the panel were investigated to determine the zones of intensive roof deformation. A numerical model FLAC3D (Fast Lagrangian Analysis of Continua in 3 Dimensions) was established to understand the results of the field tests and to map the zones in the panel with a high risk for coal bumps. The results of the field tests and the numerical modeling show that the roof deformation starts to occur at more than 30m ahead of the longwall face and the deformation starts to accelerate after a distance of 10m in front of the longwall face. Large and rapid roof deformation is considered to be an important precursor of coal bump occurrence during the extraction of an island longwall panel. Based on these results, a stress-relief technology using boreholes was investigated through numerical methods. The modeled results suggest that the abutment stress could be released by drilling boreholes in the zones prone to coal bumps. The effectiveness of the stress release increased with the borehole length and decreased with the borehole spacing. [Copyright &y& Elsevier]

In order to study the best air-decking ratio of the hole-bottom air space charging to reduce blasting vibration effect, a field experiment was conducted. First, based on the experimental data, using wavelet decomposition combined with the AOK time-frequency representation, peak particle velocity of blasting seismic waves, dominant frequency, duration of dominant frequency, duration of preponderant frequency and frequency-band energy ratio was studied under different air-decking ratio. The results show that, with the increase of air-decking ratio, peak particle velocity of blasting seismic waves and dominant frequency are decreasing, duration of dominant frequency and duration of dominant frequency are increasing, and frequency-band energy ratio is developing toward low frequency. Then, with 7.812 5-15.625 0 Hz frequency-band energy which is closed to natural frequency of buildings as the indicator, the best air-decking ratio to reduce blasting vibration has been selected, and combined with practical work, the feasibility and effectiveness of the method were proved. [ABSTRACT FROM AUTHOR]

Abstract: In this study, exergy analysis of a borehole thermal energy storage system (BTES) for cooling season is carried out. A comprehensive case study is conducted based on the system at University of Ontario Institute of Technology in Oshawa, Canada, and actual thermal load data are employed for analysis. The exergy destruction rates of each system component and overall system are calculated and studied for comparison purposes. It is determined from the analysis that the exergy destructions in a system particularly take place in condensers of cooling systems. Also, it is found that condenser and evaporator temperatures have strong effects on the exergetic performance of the system. For system performance analysis and improvement, exergy efficiencies of the overall BTES are investigated and determined to be a maximum of 62%. [Copyright &y& Elsevier]

Tracer tests performed under natural or forced gradient flow conditions can provide useful information for characterizing subsurface properties, through monitoring, modeling, and interpretation of the tracer plume migration in an aquifer. Nonreactive tracer experiments were conducted at the Hanford 300 Area, along with constant-rate injection tests and electromagnetic borehole flowmeter tests. A Bayesian data assimilation technique, the method of anchored distributions (MAD) (Rubin et al, 2010), was applied to assimilate the experimental tracer test data with the other types of data and to infer the three-dimensional heterogeneous structure of the hydraulic conductivity in the saturated zone of the Hanford formation. In this study, the Bayesian prior information on the underlying random hydraulic conductivity field was obtained from previous field characterization efforts using constant-rate injection and borehole flowmeter test data. The posterior distribution of the conductivity field was obtained by further conditioning the field on the temporal moments of tracer breakthrough curves at various observation wells. MAD was implemented with the massively parallel three-dimensional flow and transport code PFLOTRAN to cope with the highly transient flow boundary conditions at the site and to meet the computational demands of MAD. A synthetic study proved that the proposed method could effectively invert tracer test data to capture the essential spatial heterogeneity of the three-dimensional hydraulic conductivity field. Application of MAD to actual field tracer data at the Hanford 300 Area demonstrates that inverting for spatial heterogeneity of hydraulic conductivity under transient flow conditions is challenging and more work is needed. [ABSTRACT FROM AUTHOR]

Abstract: Coal and carbonaceous shale samples were collected from two boreholes (BH 94 and BH 120) in Awgu formation of Middle Benue Trough, Nigeria. Source rock potentials of the samples were studied using biomarkers and carbon isotopic composition. Biomarkers in the aliphatic fractions in the samples were studied using Gas Chromatography–Mass Spectrometry (GC–MS). The Carbon isotope analysis of individual n-alkanes in the aliphatic fraction was performed using Gas Chromatography–Combustion–Isotope Ratio Mass Spectrometer (GC–IRMS). The abundance of hopanes, homohopanes (C31–C35), and C29 steranes in the samples indicate terrestrial plant, phytoplankton and cyanobacteria contributions to the organic matter that formed the coal. High (Pr/Ph) ratio (3.04–11.07) and isotopic distribution of individual alkanes showed that the samples consisted of mixed terrestrial/marine organic matter deposited under oxic condition in lacustrine–fluvial/deltaic depositional environment. The maturity parameters derived from biomarker distributions showed that the samples are in the main phase of oil window. [Copyright &y& Elsevier]

Summary: Electrical resistivity tomography is a well-known technique to monitor fresh-salt water transitions. In such environments, boreholes are often used to validate geophysical results but rarely used to constrain the geoelectrical inversion. To estimate the extent of salt water infiltration in the dune area of a Natural Reserve (Westhoek, Belgium), electrical resistivity tomography profiles were carried out together with borehole electromagnetic measurements. The latter were used to calculate a vertical variogram, representative of the study site. Then, a geostatistical constraint, in the form of an a priori model covariance matrix based on the variogram, was imposed as regularization to solve the electrical inverse problem. Inversion results enabled to determine the extension of the salt water plume laterally and at depth, but also to estimate the total dissolved solid content within the plume. These results are in agreement with the hydrogeological data of the site. A comparison with borehole data showed that the inversion results with geostatistical constraints are much more representative of the seawater body (in terms of total dissolved solids, extension and height) than results using standard smoothness-constrained inversion. The field results obtained for the Westhoek site emphasize the need to go beyond standard smoothness-constrained images and to use available borehole data as prior information to constrain the inversion. [ABSTRACT FROM AUTHOR]

Abstract: Model experiments in the laboratory are used to find the optimal measuring and interpretation parameters that affect the quality of the results for the improved application of resistivity tomography between boreholes or between the surface and a tunnel. The experiments have shown that the detection ability of each crosshole electrode array is different and depends on the form of the sensitivity pattern. The bipole–bipole array, with current and potential pairs in different boreholes, has quite low signal and very good resolution of confined bodies in homogeneous half-spaces, but the resolution decreases as the half-space becomes more complex. The bipole–bipole array with the electrodes of each bipole in different boreholes produces a stronger signal, causing the models to be greatly influenced, even by the presence of small targets. However, the resolution quality is poor, mainly in the middle of the area between the boreholes. Pole–bipole array shows good resolution of the targets detection, but it is less accurate when conditions become noisier. The pole–tripole array has the best resolution, even when the environment becomes more complex or noisier, but the produced models have also many artifacts. The combined arrays'' data inversion yields the greatest influence of the targets on resistivity models, usually with very good positioning or shape resolution, but with many more intense artifacts, since this method inevitably combines the advantages and disadvantages of each array. A new approach to improve the quality of resistivity models has been developed, based on a stacking technique, through the processing of different arrays'' inverted models (“MOST” technique). The improvement of the MOST models'' quality has been measured, comparing each final resistivity model with the corresponding real one, highlighting this way the efficiency of this technique, in contrary to the combined arrays'' data inversion. [Copyright &y& Elsevier]

Abstract: Borehole image logs are kind of the modern logs which are frequently used to detect small-scale fractures intersecting well in fractured reservoirs. Electrical imaging tools like FMS (Formation MicroScanner) and FMI (Fullbore Formation MicroImager), electrically scan the borehole wall and deliver a pseudo-picture of the formation. Characteristics of fractures such as type, aperture and orientation can be determined by interpreting these logs. In this paper, we attempt to evaluate the ability of electrical image logs in detecting fractures and other geological features of a carbonate reservoir (Asmari) and explain the possible reasons of mismatch between the image log and core. To achieve this goal, we have compared the FMS of a well with the core. The results are verified with FMI and core data from seven nearby wells. Comparison of the FMS with the core revealed that FMS, as representative of electrical image logs, is robust in detecting open fracture and anhydrite; it is average in detecting bedding plane and flexural slip and is weak in detecting filled fracture, fault and compactional feature in carbonate reservoirs. [Copyright &y& Elsevier]

Abstract: Three Central Appalachian boreholes, each representing a distinct coal rank range (high volatile A bituminous, medium through low volatile bituminous, and semianthracite), were analyzed for vitrinite maximum reflectance and illite crystallinity for the coals and shales, respectively. The results reflect differential perfection of illite along its 001 crystallographic axis and its internal elemental arrangement, resulting from variations in ionic composition and strength of interstitial fluids and/or the type and composition of the dominant illite precursors. Despite the differences in the rate of metamorphic reaction in illite and vitrinite, generally, among the Weaver, Flehmig, and Kübler illite crystallinity indices, the Kübler index shows the best correlation with vitrinite maximum reflectance. [Copyright &y& Elsevier]

In view of the collapsibility of borehole face and coal formation pollution resulted from drilling fluid, developed the light weight drilling fluid through optimization experiments of hollow glass microspheres light weight additive and evaluation experiments of its influence on drilling fluid performances. The density of the developed light weight drilling fluid was reduced by adding hollow glass microspheres. The evaluation experiments of drilling fluid performances show that the light weight drilling fluid has good rheological property and filtration property, and its mud cake is thin and tight, its API filtration loss is less than 5 mL, and is less than 15 mL at high temperature and pressure, and after aging 16 h at 120 °C, the drilling fluid performance is stable, which shows that it has good temperature tolerance. Moreover, this drilling fluid has a lot of good properties, such as antipollution, anti-sloughing, blocking, sedimentation stability and formation protection. This light weight drilling fluid, whose density is 0.95 g/cm³, was applied in one well for field trial successfully at Qinnan demonstration plot. Good performance on protecting coal formation from pollution, which is good for sequent development of coalbed methane, was observed. [ABSTRACT FROM AUTHOR]

Abstract: The objective of this study was to evaluate the effects of rainwater infiltration on volumetric water content (VWC), groundwater level, and ground and surface water quality in mine waste rock and tailings. The VWC and electrical conductivity was recorded with sensors installed at five depths. Three boreholes 7–13m in depth were drilled to monitor groundwater level and EC, and to collect water quality samples. During the rainy season, as the water front moved deeper into the tailings, EC values increased. These results and the presence of oxidized and bleached zones in the tailings indicated that soluble salts formed in the vadose zone were migrating downward. Water analyses indicated that the groundwater was contaminated by Zn (282mg L−1), Cu (59.3mg L−1), Cd (10.1mg L−1), and Pb (0.51mg L−1). All elements were significantly correlated with total dissolved solids (TDS), and correlation coefficients greater than 0.90 were found for Zn–Pb, Zn–Mn, Zn–SO4, Pb–Mn, Cu–Al, Mn–SO4, Al–Si, Na–Mg, and Mg–Ca. It was concluded that 20cm depth of the soil cover on the tailings was not enough to prevent water infiltration and ground or surface water contamination. [Copyright &y& Elsevier]

This paper reports about the relationship between starting hole geometry and twist drill performance, which is determined by the location error and diameter of the drilled borehole as well as the tool life of the employed twist drills. The experimental results lead towards the conclusion that the type of starting hole has a significant effect on borehole quality. This, however, is not as commonly assumed attributed to a variation in the location error of the different starting holes themselves, but to how a starting hole allows the subsequent twist drill to engage in the cutting process. Although twist drills that drill straight into the workpiece material achieved the longest tool life due to a gentle engagement, a deep starting hole ('pilot hole') results in the most satisfying overall twist drill performance. [ABSTRACT FROM AUTHOR]

The purpose of the study was to compare stress values obtained from Acoustic Emission and Compact Conical-Ended Borehole Overcoring stress measurement techniques applied at an underground limestone mine in Japan, and to investigate the effect of rock anisotropy and confining pressure on the Kaiser Effect level which has been used to determine in situ stresses by the Acoustic Emission technique. Initially, Acoustic Emission tests were carried out on limestone cores extracted from horizontal boreholes in a pillar and hanging wall in the underground mine. The stress values obtained were two or three times greater than those obtained by the Compact Conical-Ended Borehole Overcoring method. In the second stage, the anisotropy of a granite block was determined by P-wave measurements. Core specimens extracted from two different directions were pre-loaded under axisymetric triaxial conditions by applying a series of differential stresses. The cores were then re-loaded under uniaxial conditions and the Kaiser Effect levels were determined. It was concluded that both the anisotropy and confining pressure have an important influence on the Kaiser Effect level. [ABSTRACT FROM AUTHOR]

Abstract: This paper is focused on the drilling of bore holes with high length-to-diameter ratios and diameters less than 2mm which are needed, for example, in medical and automotive applications. In the presented research, the influence of cutting data and tool design on tool wear and chip formation has been analysed. First the experimental set-up is described followed by an in-depth process analysis of the single-lip deep hole drilling process under investigation. The next section deals with a process combination, where laser and mechanical drilling are combined in order to improve process reliability and productivity. [Copyright &y& Elsevier]

Over the past few years, new abstractions from the Sherwood Sandstone aquifer in North West England have only been permitted in areas with known saline intrusion subject to the abstractor demonstrating that the new pumping will not cause deep-seated saline groundwater to up-cone. This requirement has necessitated drilling deep boreholes to prove the depth to the fresh–saline groundwater boundary and also to facilitate long-term monitoring. Vertical salinity profiles were defined during borehole construction in two such investigations by monitoring the conductivity of water samples obtained from drilling returns during air-flush drilling and later by the geophysical logging of the completed boreholes. Deep piezometers were constructed allowing samples to be taken from specific depths for chemical analysis, and the results have been compared with the earlier data. These methods successfully defined the broad features of vertical salinity profiles within the aquifer and showed that measurements during drilling provide a practical and economic indication of the position of the interface so that the borehole final depth can be determined. [ABSTRACT FROM AUTHOR]

Abstract: This work presents palynological and palynofacies analyses from early Silurian Tanezzuft Formation shales recovered from core material of borehole CDEG-2a drilled in Dor el Gussa at the eastern margin of the Murzuq Basin, southern Libya. The material has yielded well-diversified palynomorph and chitinozoan assemblages and organic matter from a depth interval of 37.41 to 50.64m. The interval above 37.41m is weathered and barren of palynomorphs. The palynomorph assemblage present from the 37.41–50.64m interval is early Llandovery (Rhuddanian–early Aeronian) in age and was deposited in a shallow, open marine (but proximal) environment with a minor landward shift between 43.02 and 46.13m. The oldest chitinozoan assemblage recorded in the studied core samples can be referred to the fragilis regional Biozone. However, because the relative abundance of Spinachitina fragilis is low, it is considered here that the deepest part of the borehole (at 50.64m) does not penetrate the actual base of the Rhuddanian. Thus, a Rhuddanian–earliest Aeronian age is retained here for the corresponding strata in borehole CDEG-2a. The core includes the boundary between the fragilis and nuayyimensis biozones, which was until now unknown from southern Libya. Furthermore, we describe a new chitinozoan species, Angochitina murzukensis sp. nov. The intervals 37.41–42.36m and 46.48–50.64m show a dominance of amorphous organic matter (AOM) Types 1 and 2, suggesting an oil-prone potential, in contrast to interval 43.02–46.13m, which is dominated by land-derived (vitrinite) Type 3 suggesting a gas-prone potential. The Ordovician–Silurian boundary and therefore the glacial-related Late Ordovician deposits have not been penetrated by the borehole. In all likelihood, this boundary is not far below the bottom of borehole CDEG-2a. [Copyright &y& Elsevier]

Abstract: We present a rigorous validation of the analytical Amadei solution for the stress concentration around an arbitrarily orientated borehole in general anisotropic elastic media. First, we revisit the theoretical framework of the Amadei solution and present analytical insights that show that the solution does indeed contain all special cases of symmetry, contrary to previous understanding, provided that the reduced strain coefficients and are not equal. It is shown from theoretical considerations and published experimental data that the and are not equal for realistic rocks. Second, we develop a 3D finite element elastic model within a hybrid analytical–numerical workflow that circumvents the need to rebuild and remesh the model for every borehole and material orientation. Third, we show that the borehole stresses computed from the numerical model and the analytical solution match almost perfectly for different borehole orientations (vertical, deviated and horizontal) and for several cases involving isotropic, transverse isotropic and orthorhombic symmetries. It is concluded that the analytical Amadei solution is valid with no restriction on the borehole orientation or the symmetry of the elastic anisotropy. [Copyright &y& Elsevier]

Abstract: This paper deals with the formulation of global relationships between the forces and moments acting on a PDC drag bit and the kinematic variables describing the penetration of the tool into the rock. It considers the general situation where the bit penetration is characterized not only by an axial but also by lateral and angular components, as it is the case when drilling a deviated well with a bit tilted on the borehole axis. These interface laws serve as boundary conditions for the drillstring treated as a rod when modeling the propagation of the borehole. While the relationships between forces and penetrations assume the bit to be reduced to a point, determination of the parameters of the interface laws requires information about the bit geometry and the cutter characteristics, as well as knowledge about the local cutter/rock interaction. We show that it is actually possible to construct the interface laws by using the device of an equivalent blade, which embodies the properties and geometry of the bit. The use of this device eliminates the need to consider the interaction of each individual cutter with the rock during one revolution of the bit. The approach is illustrated for a cylindrical bit. In this case, the interface parameters and their dependence on the bit tilt can be determined in closed form. [Copyright &y& Elsevier]

The article presents a study on the geodynamics and stress characteristics of the zone near the gas borehole in drilling. It says that the vertical borehole drilling process was considered on the permeability front and mud cake front that has axial symmetry. It states that the study used a mathematical model within the Biot theory of porous elasticity for the establishment of the drill fluid filtrate penetration area during borehole drilling at quasi-static stresses conditions. The result shows that stress characteristics and hydrodynamic in the area close to the borehole have different pressures and the comparison was made with the outcomes for the nonelastic rock matrix.

Abstract: This paper discusses some aspects of parameters estimation used in in-situ thermal response tests of ground heat exchangers, including sensitivity analysis and comparison of iterative minimization algorithms. First, several sensitivity coefficients of parameters and uncertainties occurring in in-situ tests are examined in depth. Starting from an analytical heat transfer model of borehole ground heat exchangers, sensitivity coefficients for single U-tube ground heat exchangers are of analytical forms. The sensitivity analysis provides some general and new guidelines for mitigating the influence of testing uncertainties. Next, Monte Carlo simulation is performed to evaluate reliability of two powerful minimization algorithms, the Levenberg–Marquardt method and a trust region method subject to bounds. The Monte Carlo simulation shows that if thermal diffusivity of soil is an estimated parameter, the Levenberg–Marquardt method may result in unreliable results, and its performance depends strongly on the quality of the initial guessed values. In contrast, the interior trust region method considered in this paper can produce more reliable results, and its performance depends on the range of input parameters bounds. Finally, feasibility of the highlighted methodology is illustrated by applying it to two real in-situ thermal response tests. [Copyright &y& Elsevier]

SUMMARY Seismic velocity anisotropy measurements are made of a fractured metamorphic formation from the 2.5-km-deep International Continental Scientific Drilling Programme (ICDP) borehole in Outokumpu, Finland. Three component walk-away vertical seismic profile (VSP) measurements are made along two source-line azimuths at three receiver depths (1000, 1750 and 2500 m) and incidence angle-dependent qP- and qS-wave velocities are extracted with a τ- p method. The highest qP-wave anisotropy, 13.6 per cent ( vfast= 6160 m s−1, vslow= 5370 m s−1), is measured between 1000- and 1750-m depth, with anisotropy of up to 9.4 per cent ( vfast= 6090 m s−1, vslow= 5540 m s−1) measured between 1750 and 2500 m depth. The top ∼1300 m of the region is composed of a homogeneous, strongly intrinsically anisotropic biotite-rich schist, and is sampled by the shallowest walk-away profile. Anisotropy of up to 11.1 per cent ( vfast= 5950 m s−1, vslow= 5320 m s−1) is measured by the walk-away VSP between 50 and 1000 m depth, along with shear wave splitting averaging 5 per cent (180 m s−1). Laboratory-derived intrinsic anisotropy of the schist cannot by itself explain the degree or orientation of the anisotropy measured in the walk-away VSPs, however, a model which modifies the intrinsic stiffnesses by the inclusion of a single set of dipping, aligned cracks allows the observed in situ velocities to be reproduced. Forward modelling of the qP-wave walk-away VSP measurements from 50 to 1000 m depth is undertaken using an effective medium model to develop a 3-D velocity model of this region. An orthorhombic medium is used to represent the intrinsic anisotropy of the biotite-rich schist, and a single set of aligned cracks is added to give a bulk elastic stiffness. The resulting model predicts the schist to have an overall anisotropy of 16.8 per cent, with qP-wave velocities of up to 6315 m s−1. The accuracy of the model is assessed through its fit to the walk-away VSP measurements as well as a comparison to known geology of the region. [ABSTRACT FROM AUTHOR]

During ultra-deepwater drilling operations for oil and gas, the choice of the pump displacement is an important problem that concerns safety and economic results of offshore drilling operations. In addition to three conventional constraint conditions, another constraint condition has been established to calculate the critical pump displacement. The collapse pressure, pore pressure, fracture pressure, and sufficient safety margin are taken into account in the fourth constraint condition. The method is presented in detail. Based on the equivalent circulating density calculation model in ultra-deepwater drilling, the formation pressure data, and the safety coefficient, the result of critical pump displacement can be obtained. The calculation procedure of the critical pump displacement is presented through an example. According to the analysis, the safety margin is one of the critical limitations for pump displacement and the pump displacement determination is dependent on all of these four constraint conditions. [ABSTRACT FROM PUBLISHER]

Abstract: This paper investigates the relative performance of the sonic echo (SE), impulse response (IR), and parallel seismic (PS) tests using a field constructed pile foundation incorporating simulated defects. Tests were performed before and after the construction of a pile cap. According to the experimental results, the SE method has the best performance with regard to defect detection in an isolated pile. The results of the PS test were more consistent with regard to the length determination of the piles with a cap than those obtained using the SE and IR methods. The pile length estimated from the PS method increases with increasing borehole-to-pile distance, but this over-estimation can be reduced by applying length correction factors, thus providing more conservative estimations of the pile length. The two length correction approaches for the PS test produced similar results. [Copyright &y& Elsevier]

Groundwater is a strategic water resource in rural Limpopo Province and it accounts for almost 70% of rural domestic water supply. The resource is available throughout the Province in varying quantities and qualities depending on the hydrogeological properties of the underlying aquifer. These properties are mostly secondary in nature and are constrained by the processes of weathering, faulting, fracturing and the influence of intrusive rocks. These properties define typical fractured aquifers in which the selection of drilling sites requires a thorough scientific approach to locate a successful productive borehole. While most water service authorities in the Province have been randomly developing new boreholes with limited success rates, the analysis of datasets in the newly established groundwater data repository, the Limpopo Groundwater Resource Information Project (GRIP) demonstrates that large quantities of groundwater can be obtained and used for bulk supply if the drilling sites are scientifically selected. The GRIP dataset contains 24 922 entries of which 4 000 were tested. The pumping test results indicate that an estimated 576 000 m3/d (210 Mm3/a) can be sustainably abstracted from boreholes in approximately 2 500 villages that are dispersed throughout the Province. However, more than 50% of these boreholes are unequipped of which 3 000 can provide a combined yield of 109 Mm3/a based on a 24 h abstraction rate. These results show that groundwater can be developed as a potential viable bulk-water supply source. This paper attempts to demonstrate, using the existing GRIP dataset, that groundwater is an underutilised resource that can be viably and cost-effectively developed as an alternative bulk water source or conjunctively with surface water. [ABSTRACT FROM AUTHOR]

Abstract: Gas emission rate from borehole is one of the most important indexes for the coal and gas outburst prediction. The mathematical model of gas flow in the coal seam, gas flow into the measuring chamber, gas pressure change in the measuring chamber, and gas flow out of the chamber through the pipe is established. Gas migration in the coal seam, gas pressure in borehole chamber and gas flow in pipe is simulated using the finite difference method. Gas emission rate is obtained under dynamic boundary conditions. The influence of gas storage parameters on gas emission rate from borehole is analyzed. Results show that: the gas pressure and the permeability coefficient have great impacts on the value of gas flow quantity in borehole. The larger the original gas pressure of coal seam and the permeability coefficient of coal seam are, the greater the maximum value of gas emission rate form borehole and the later the maximum appears. [Copyright &y& Elsevier]

The solution of the problem of the mining boreholes productivity increase is very urgent for gaseous fuel extraction from coal and slate deposits as it may help to produce greater volume of methane from a production unit. Purpose. To estimate the parameters of the combustible gases extraction technology based on change of temperature modes of gasification process. Methodology. Analysis of existing experience of associated gas production, determination of the research guidelines, substantiation of the technological process parameters, determination of the material thermal balance of gasification, designing of the schemes and flowsheets of underground gas generator have been carried out. Findings. Characteristics of different zones of a coal seam appearing during frac job has been determined and reasonability of preliminary degassing of underground gas generator has been substantiated. Originality. The character of the gasification thermal processes behavior in the conditions of high interference of hard fuel layers and new values of pressure change in hydraulic fracturing dependence on the mining-andgeological parameters of rock massif. Practical value. The principle network of gaseous fuel production from coal and slate deposits has been improved and the operation modes of underground gas generator have been developed [ABSTRACT FROM AUTHOR]

Summary: Heat-pulse flowmeter can be used to measure low flow velocities in a borehole; however, bias in the results due to measurement error is often encountered. A carefully designed water circulation system was established in the laboratory to evaluate the accuracy and precision of flow velocity measured by heat-pulse flowmeter in various conditions. Test results indicated that the coefficient of variation for repeated measurements, ranging from 0.4% to 5.8%, tends to increase with flow velocity. The measurement error increases from 4.6% to 94.4% as the average flow velocity decreases from 1.37cm/s to 0.18cm/s. We found that the error resulted primarily from free convection and frictional loss. Free convection plays an important role in heat transport at low flow velocities. Frictional effect varies with the position of measurement and geometric shape of the inlet and flow-through cell of the flowmeter. Based on the laboratory test data, a calibration equation for the measured flow velocity was derived by the least-squares regression analysis. When the flowmeter is used with a diverter, the range of measured flow velocity can be extended, but the measurement error and the coefficient of variation due to friction increase significantly. At higher velocities under turbulent flow conditions, the measurement error is greater than 100%. Our laboratory experimental results suggested that, to avoid a large error, the heat-pulse flowmeter measurement is better conducted in laminar flow and the effect of free convection should be eliminated at any flow velocities. Field measurement of the vertical flow velocity using the heat-pulse flowmeter was tested in a monitoring well. The calibration of measured velocities not only improved the contrast in hydraulic conductivity between permeable and less permeable layers, but also corrected the inconsistency between the pumping rate and the measured flow rate. We identified two highly permeable sections where the horizontal hydraulic conductivity is 3.7–6.4 times of the equivalent hydraulic conductivity obtained from the pumping test. The field test results indicated that, with a proper calibration, the flowmeter measurement is capable of characterizing the vertical distribution of preferential flow or hydraulic conductivity. [Copyright &y& Elsevier]

Abstract: Chemical and isotopic data for 23 geothermal water samples collected in New Zealand within the Taupo Volcanic Zone (TVZ) are reported. Major and trace elements including Li, B and Sr and their isotopic compositions (δ7Li, δ11B, 87Sr/86Sr) were determined in high temperature geothermal waters collected from deep boreholes in different geothermal fields (Ohaaki, Wairakei, Mokai, Kawerau and Rotokawa geothermal systems). Lithium concentrations are high (from 4.5 to 19.9mg/L) and Li isotopic compositions (δ7Li) are homogeneous, ranging between −0.5‰ and +1.4‰. In particular, it is noteworthy that, except for the samples from the Kawerau geothermal field having slightly higher δ7Li values (+1.4%), the other geothermal waters have a near constant δ7Li signature around a mean value of 0‰±0.6 (2σ, n =21). Boron concentrations are also high and relatively homogeneous for the geothermal samples, falling between 17.5 and 82.1mg/L. Boron isotopic compositions (δ11B) are all negative, and display a range between −6.7‰ and −1.9‰. These B isotope compositions are in agreement with those of the Ngawha geothermal field in New Zealand. Lithium and B isotope signatures are in a good agreement with a fluid signature mainly derived from water/rock interaction involving magmatic rocks with no evidence of seawater input. On the other hand, Sr concentrations are lower and more heterogeneous and fall between 2 and 165μg/L. The 87Sr/86Sr ratios range from 0.70549 to 0.70961. These Sr isotope compositions overlap those of the Rotorua geothermal field in New Zealand, confirming that some geothermal waters (with more radiogenic Sr) have interacted with bedrocks from the metasedimentary basement. Each of these isotope systems on their own reveals important information about particular aspects of either water source or water/rock interaction processes, but, considered together, provide a more integrated understanding of the geothermal systems from the TVZ in New Zealand. [Copyright &y& Elsevier]

Slotted charge has significant guiding effect on blast energy. Slotted charge was introduced into cut blast, and the idea of "cut to drivage" was put forward. Divided a certain range of central rock part from the surrounding with slotted charge blast. This method avoids the disadvantage of single free surface and great clamping effect. Utilized the blast energy of following boreholes, break the rock and throw the fragment out of cavity. Perform numerical simulation of rectangular cut blast. The energy along kerfs' direction is released in priority, and the peak value of point along kerfs is above 200 MPa, which forms the penetration of cracks. In separate cut blast, the utilization rate of borehole reaches to 97.8%. In full section blast,the average utilization rate of borehole reaches to 96.9%. Field tests validate the feasibility of cut blasting with slotted charge. [ABSTRACT FROM AUTHOR]