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This paper presents a new method of combining Minimum Quantity Lubricant (MQL) with ultrasonic assistance in deep hole drilling processes for difficult-to-cut materials, using internal coolant tool...

The paper discusses the basic principles underlying a new approach to the control of seismic activity in tectonic fault zones. A key component of the approach is the use of controlled man-made impacts on highly stressed fault segments. The applicability of the approach was verified in field experiments on seismically active fault segments of the Baikal rift zone and collision structures of Mongolia. The paper reports the most striking examples of applying man-made pulsed vibrational impacts to highly stressed fault segments in combination with controlled fluid injection into deep wells. The results of impacts on the studied fault segments are discussed in the light of new geological data on physicochemical processes in the zones of ancient seismically active faults and recent advances in deep drilling for hydrocarbon exploration and production. A justification is provided for the concept of controlled shear stress relaxation in potentially hazardous fault segments showing the signs of earthquake preparation. The possible implementation of the proposed concept in the near future is discussed.

Der Beitrag befasst sich mit Teilaspekten bei der Entwicklung von Methoden zur gezielten, bearbeitungsparallelen Oberflächenkonditionierung beim Tiefbohren. Konkret handelt es sich um messtechnische und simulationsbasierte Ansätze zur Identifikation von thermomechanischen Prozesszuständen beim BTA- und ELB-Verfahren. Hierbei werden Möglichkeiten zur Gewinnung von Prozessdaten sowohl mit einer in-situ eingesetzten Sensorik als auch mit begleitend durchgeführten FEM-Simulationen betrachtet. Diese Daten bilden die Grundlage einer Prozessregelung für die beiden Tiefbohrverfahren. Im zweiten Teil werden nun die Arbeiten und Ergebnisse zum ELB-Tiefbohren behandelt. The article deals with aspects of developing methods specifically for surface conditioning in deep hole drilling parallel to machining. This involves metrological and simulation-based approaches for identifying thermo-mechanical process conditions in both BTA and ELB process. Ways for obtaining process data both with sensor technology used in-situ and with FEM simulations performed concomitantly are investigated. These data form the basis of a deep hole process control. The second part presents the work and the results on single lip deep hole drilling.

This paper develops a simulation-based model to derive critical maintenance parameters towards optimizing a deep drilling rig availability and maintenance costs. Full factorial analysis is performed to derive the effects and interactions of the derived parameters, based on which ones with a significant effect on the availability and maintenance cost are selected. The case study based model incorporates maintenance, spares and workforce strategies for a geothermal drilling rig. The results offer essential maintenance decision support to both the management and maintenance team of the company and have the potential of further offering insights that eventually reduce the cost of drilling.

Problem Statement and Purpose. In Lower Pridnestrovie, the Silurian system rocks are widely distributed, well stratified, and composed of thick mainly limestone-do­lomite strata with thin layers of anhydrite, reaching 243-400 m in the southern part. The last geological survey works were carried out in the study area in the early 1990s. Reinterpretation of the received factual material of previous years can give more ac­curate ideas about the stratigraphy of the pre-Mesozoic sediments of the region.Data & Methods. For the article, the deep drilling data for 28 wells crossing the Si­lurian served as material. While processing the actual material, modern GIS methods were used. The actual material on the well columns was compiled in the database "Mane base" created in the software product K-MINE.Results. The article shows the comparison of Silurian stratigraphical schemes of re­search area of different authors as well as the contradictions are examined. The first campaigns of geological exploration of the territory were conducted in the 1960s (Bukatchuk et al., 1967). Following the chronology of the Lower Palaeozoic of Po­dillya of that time, accordingly, the Moldavian horizons and strata were assigned to older epochs and ages of the Silurian. The refinement in the 1970s of the stratigraph­ical scheme of the Silurian of Western Ukraine allowed Moldavian geologists in the 1980s to redistribute the intervals in earlier drilled (1960s) exploration wells to new local formations and members of corresponding age (Bukatchuk et al., 1985). The last survey campaigns in the region in the late 1980s-early 1990s used this revised stratigraphical scheme (Zakharov et al., 1987; Pozdnyakov et al., 1992). As the result of research carried out the data on Silurian formations were collected and system­atized, lithological characteristics were described, and characteristic faunal elements were identified for objective geochronological dating of stratigraphic divisions. As the main outcome of the work, the local stratigraphic scheme was presented. Eight for­mations were assigned: Morosesti and Step-Soci Formations (Llandovery), Balti For­mation and Lower Puhoi Subformation (Wenlock), Upper Puhoi Subformation, Ichel Formation and lower parts of Chisinau Formation (Ludlow), upper parts of Chisinau Formation, Rashkiv and Zvenyhorod Formations (Pridoli).

In connection with the need to increase the energy resources of Ukraine, it is essential to expand the areas and depths of prospecting, as well as to improve the methodology and technology of oil and gas exploration. The most promising area for the search for new oil and gas fields in Ukraine remains the Pripyat-Dneprovsko-Donetsk oil and gas province. Increasing the depth of new energy sources because of the increasing cost of exploration and deep drilling requires more accurate and efficient predictions, which should be based on a more rigorous scientific substantiation of new directions of work and the application of new efficient technologies. The article develops the concept of deep degassing of the Earth, which is of great importance for the development of modern ideas about the formation and geological history of the Pripyat-Dnieper-Donetsk oil and gas province. The authors considered the nature of oil and gas accumulation areas and their relationship with the “pipes” of deep degassing of the Earth, as well as the possibilities of structural-tectonic, lithological-geochemical and remote sensing methods in identifying new oil and gas fields in the Pripyat-Dnieper-Donetsk oil and gas province and signs of their connection with «pipes» hydrocarbon deep degassing of the Earth. To implement new methodology and technology of prospecting, exploration of oil and gas fields, the article proposes to make wider use of the modern capabilities of satellite methods, which make it possible to quickly cover large areas with multiple surveys, increase the efficiency of solving geological problems, and also significantly reduce the cost of oil and gas exploration.

The deeply eroded Acraman structure in the Mesoproterozoic Gawler Range Volcanics, Gawler Craton, South Australia, ranks among the world’s largest known impact structures, with a transient crater ∼...

In the list of environmental pollutants, mercury is one of the first places. It is mercury, its inorganic and especially organic compounds belong to extremely toxic substances of the first class of danger.Mercury has been known since ancient times, it is mentioned in the writings of Aristotle, Theophrastus, Pliny the Elder, Vitruvius and other ancient scholars. The Latin name for this metal is “Hydrargium”, given to mercury by Greek physician Dioscorides (1st century B.C.), means in translation “silver water”. The most important and ancient in Ukraine is the Mykytiv mercury deposit, which was opened in 1879. and operated since 1885. Production of mercury until 1914 was 300–400 t/year (most of it was exported). After the revolution and the war it was slowly recovered (127 tons in 1926), in 1935–1940 it is annually brought to about 300 tons. After the Second World War, the Mykytiv deposit was built. Discovered in it reserves (up to a depth of 300 m) were evaluated in 6.000 tons in 1927, after deep drilling was introduced in the 1960s. they have increased slightly. In the world economy, mercury is widely used in the electrical engineering and instrument industry, laboratory and medical practice, in the production of chlorine/alkali, in agriculture (included in fertilizers), in small-scale mining of gold and silver and other fields. No other chemical element belonging to the first class of danger has such wide use in production processes, products, substances and such multivariate penetration into the organism (with air, food, water, through the skin) as mercury and its compounds. The main source of mercury poisoning is mercury vapor and dust of mercury compounds. The toxicity of metallic mercury is due to the fact that while inhaling its vapors more than 80 % of the mercury is absorbed by the brain, kidneys and other internal organs, leading to he devastating consequences primarily on the central nervous system and kidneys. Mercury semi withdrawal period from humans is from 35 to 96 days. The average semi withdrawal period from the blood is 65 days, from hair 72 days, in total from the organism - 76 days. A longer semi withdrawal period of mercury from the brain than from other organs has been recorded in experimental animal searches. In humans, high levels of mercury in brain tissue were detected 10 years after it ceased contact with a toxic substance. Mercury poisoning can be acute or chronic. In everyday life, most often find the second option.

Analysis of multichannel seismic profiles collected on the continental rise off the Sabrina Coast, East Antarctica, has allowed the determination of the acoustic features that are indicative of major evolution steps of the East Antarctic Ice Sheet (EAIS) and highlights the role of meltwater that originated from Totten Glacier in shaping the margin architecture. The arrival of marine-terminating glaciers into the coastal region was recorded by an enhanced sediment input on the continental rise and the nucleation of channel-levees. Downslope sedimentary processes were dominant throughout the Late Cenozoic, testifying to the progressive growth of a highly dynamic, temperate ice sheet on the continent. The last evolutionary step marks the transition to when a full polar glacial regime occurred. The development of a prograding wedge with steeply dipping foresets on the continental shelf and slope exemplifies sedimentation at this time. Other sub-sea-floor observations indicate that downslope fluxes, triggered by glacial meltwater, were still able to deeply erode and deliver sediments to the rise area. This study's findings have led to the identification of expanded and well-preserved sedimentary successions, which we suggest should be considered as priority targets for future International Ocean Discovery Program deep drilling due to the sensitivity of the ice sheet in this area., This study is funded by Italian Programma Nazionale di Ricerche in Antartide (PNRA) under the TYTAN Project. The Marine National Facility Survey IN2017-V01 survey was supported by the Australian Government through Australian Antarctic Science grant AAS#4333 and Australian Research Council grant DP170100557. G. Leitchenkov acknowledges the Russian Science Foundation grant 16-17-10139.

The main task of the research was to analyze of the hydrocarbons carboniferous objects of the axial and southern slope zones of the DDD with the aim of predicting further geological prospecting works. Based on the results of the research, promising objects have been identified that determine further areas of prospecting and exploration in the perspective deposits of the Lower and Upper Carboniferous in the study area of the region.It was revealed that among the Paleozoic productive and promising complexes in the axial and southern slope zones of the DDD, on number of identified and prepared objects and their resource base, a priority complex is Carboniferous. The primary objects in that complex are Borzakovska, Brusivska, Uspenovska, Osterska and Rozdolevska structures. We are associate the priority direction of prospecting works in combined traps with anticlinal and non-anticlinal complicated structures in the Lower Carboniferous deposits with those structures. Author is proposing to carry out priority detailed seismic exploration work on the Gersenvanovskaya and Topoleva identified structures to prepare them for prospecting drilling.It has been established that the second place (after the Lower Carboniferous complex) in terms of priority and prospectively is Medium Carboniferous deposits, in which within the study area on primary importance on the searching for hydrocarbon deposits are prepared Dovgopolivska, Svyatogirska, Stepnovska, Eastern-Shebelinska and other structures. In addition, Krasnoglazovsky and Western-Ukrainian promising objects are recommended for preparation by seismic exploration for drilling.It has been proven that in the Upper Carboniferous - Lower Permian deposits, where more than half of the proven gas reserves are located. The further prospects should be associated only with the zones and blocks near salt bunch. Most perspective for hydrocarbon searching in sediments C3+P1 is Yuzhnorozpashnovsky and Severnozhkovsky objects. Western-Ukrainian object, Verkhnelannovsky northern and southern blocks and Onezshska structure are required seismic survey preparation for drilling.Due to reason, that priority structures for further exploration are located, in most, in the axial zone of the region, the main concentration of prospecting works should be carry out within that zone, not taking into account the existing depths of objects. Within the southern slope zone at shallower depths, Brusivskaya, Ostersky and Uspensky structures are prepared for drilling. The implementation of prospecting and geophysical work on the recommended objects of the studied territory of the DDD will be allow to identify new hydrocarbon deposits and replenish the fund of promising objects, that prepared for deep drilling.

The rock failure process can be characterized by several distinct stress thresholds: the crack closure stress σcc, crack initiation stress σci, crack damage stress σcd and peak stress σp. Seventy-one true triaxial compression tests were conducted to investigate the crack damage stress σcd, which is the stress at the onset of unstable crack development and dilation. Two empirical models are developed to predict the crack damage stress σcd using the intermediate principal stress σ2 and the minimum principal stress σ3. In addition, the proposed models are validated by ten results derived from the German Continental Deep Drilling Program (KTB) deep hole amphibolite. A comparison with other failure criteria also indicates the accuracy and simplicity of the proposed models. The proposed composite models show that the crack damage stress σcd gradually increases with increasing intermediate principal stress σ2 and minimum principal stress σ3. The physical meanings and ranges of six material parameters are analyzed and explained. Both the influence of the tangent Young’s modulus E and strain characteristics on the crack damage stress σcd and the inhomogeneity of the tested specimens are discussed in this paper.

The Zhongxingtun area in Inner Mongolia, China, hosts an important copper polymetallic ore field. Surface copper and molybdenum–copper orebodies have been found, without deep drilling. A new round ...

In order to enhance the understanding of the planet's geological evolution and determine whether there exists liquid water, solid ice or any other life evidence, plenty of extraterrestrial explorations have been attempted over the past decades. For future planetary drilling missions, especially unmanned drilling tasks, the autonomous drilling activity should be first verified. In order to replicate the geological formations encountered in the lunar drilling process, large amounts of lunar soil simulant are required. This simulant must be prepared at controlled densities in order to mimic the true mechanical behavior of real lunar soils. Herein, a tamping based dense soil simulant preparation method is proposed. Taking hammer's rebounding, soil's plastic-elastic deformation, and simulant's effective dense height into consideration, a novel theoretical tamping model has been established to predict the preparation parameters. Verification tests showed that the theoretical model correctly predicts the experimentally observed trend in the tamping force with the number of cycles and the optimized relative density of simulant over 180 mm depth from the top is close to that of the real deep lunar soil.

This article presents a new practical approach to gain a better insight into the machinability enhancements of ultrasonic-assisted drilling (UAD) of aluminum alloys where the depth ratio is...

A novel method to evacuate large bins of lunar regolith simulant for deep drilling tests was proposed in the current work. This method can be used to simulate a vacuous lunar regolith environment to a maximum penetration depth of 2 m. An experimental apparatus was built and is composed of a vacuum chamber, a specially designed regolith container and a vacuum pumping system. A pressure on the order of 10 Pa could be reached with the 4.3 m3 vacuum chamber when compacted lunar regolith simulant with a volume of 0.4 m3 was loaded. A theoretical model to predict vacuum degree was proposed basing on the viscous flow theory. Evacuation experiments with or without lunar regolith simulant inside the chamber were performed and the outgassing properties of lunar regolith simulant was experimentally studied. The results show that the outgassing rate of the lunar regolith simulant was about 107 times to that of the electro-polished stainless-steel.

Deep drilling operations are primarily used to produce oil, gas, and geothermal heat from reservoirs in the earth’s crust. A drill string built of thread-connected components is used to transfer mechanical energy from a drill rig on the surface to a drill bit at the bottom end. The lowest part of a drill string, which is called bottom-hole assembly (BHA), contains sophisticated sub-assemblies for process and trajectory control, formation evaluation, surface communication, power generation, and system diagnostics. The BHA can experience critical vibrations without indication further up to the string. These vibrations need to be closely monitored for process control, fatigue management, and design feedback. However, the number of sensors is too small to provide reliable indication of loads on all critical components of the drill string. Adding sensors to each component is currently neither economically nor technically viable. This paper presents an application of existing Kalman Filters, merging information from available sensors and dynamic models to obtain state estimates for all components of the BHA. The expected accuracy and limitations are discussed. The results of load extrapolation are confirmed by comparison with measurements proving the concept under inaccurately defined interaction with a downhole environment.

This paper represents a new lubricant method which is able to one-stroke drill deep holes with a length-to-diameter of 8, on the AISI SUS 304 stainless steel. By adding graphene nanosheet into typical soluble emulsion and then mixing with water, a nano fluid can be made. The results revealed that using nanofluid can provide a reduction of 4.4-fold of the drilling torque, and thus expand the tool life as many as 20 times, compared with using typical emulsion lubricant. The proper set of cutting parameters was found by using Taguchi L9 experiments as 550 rpm spindle speed and 0.05 mm/rev. The results can be expanded to apply in other deep drilling of hard-to-cut material, using inexpensive devices and avoiding peck-drilling. The proposed lubricant can also be promissing for other machining operations.

The W-CDF-S and ELAIS-S1 fields will be two of the LSST Deep Drilling fields, but the availability of spectroscopic redshifts within these two fields is still limited on deg^2 scales. To prepare for future science, we use EAZY to estimate photometric redshifts (photo-zs) in these two fields based on forced-photometry catalogs. Our photo-z catalog consists of ~0.8 million sources covering 4.9 deg^2 in W-CDF-S and ~0.8 million sources covering 3.4 deg^2 in ELAIS-S1, among which there are ~0.6 (W-CDF-S) and ~0.4 (ELAIS-S1) million sources having signal-to-noise-ratio (SNR) > 5 detections in more than 5 bands. By comparing photo-zs and available spectroscopic redshifts, we demonstrate the general reliability of our photo-z measurements. Our photo-z catalog is publicly available at \doi{10.5281/zenodo.4603178}., 6 pages, 2 figures

Summary Exploring hydrocarbon prospects in terrain and subsurface conditions of the Carpathian fold-thrust belt is a very challenging mission for traditional prospecting methods. So far, the Ukrainian part of Folded Carpathians is still poorly explored by seismic and deep drilling. In the presented paper, we illustrate possibilities of high precision gravity method applicably to HC exploration using the case study for Zhdenievo area situated in Krosno and Duklya units of the Ukrainian Carpathians. High precision gravity and magnetic surveys were performed for the purpose of a comprehensive evaluation of oil and gas prospects. Obtained results, together with all available geological and geophysical information, allowed us to identify new prospects within each analyzed horizon and to evaluate gas reserves.

Deep drilling on materials has many engineering applications. In the present work, deep drilling of stainless steel 316L has been done using brass electrode-tube on orbital electrical discharge machine (EDM). Peak current, pulse-on time, duty factor, and flushing pressure are considered as input parameters for experimentation, and influence of these parameters on EWR and MRR is investigated. It was concluded that SS-316L workpiece material and brass electrode-tube material were best machined with 3.0 A peak current at 75% duty factor.

Summary This paper reveals that potential field methods integrated with seismic data and deep drilling help in interpreting geology with better accuracy. Linear gravity and magnetic anomalies indicate tectonic disturbances while isometric anomalies characterize blocks of rocks with different lithology. The study demonstrates that suggested approach to the potential field data with the integration based on other geophysical and geological information helps specify the geological structure of the West Siberian Palaeozoic basement.

This paper deals with multiperformance optimization of machining parameters of CNC in deep drilling of SS-321. Grey relational analysis (GRA) was employed to Taguchi technique for multi-performance optimization. Taguchi technique with L18 orthogonal array was applied, and experiments were performed taking cutting fluid, cutting speed, and feed rate at different values as deep-drilling parameters. Surface roughness (SR) of drilled holes and material removal rate (MRR) was taken as multiperformance variables of deep-drilling process. Data analysis was completed by using analysis of variance (ANOVA) and response table method. Results were assured by performing a confirmation test, an improvement of 5.56% was observed in multiperformance of deep-drilling process.

The paper deals with machines able to operate in high temperature (HT°) environments. Most of standard machines are made with enameled wires insulated with a thin polymer layer. With the best availiable enameled wires, the organic nature the winding insulation limits the operating temperature to about 280°C at the hottest point. Therefore, standard machines cannot be used in the hot environments of specific applications such as deep drilling in petroleum industry, geothermal equipment or near aircraft turbines. Recent studies show that an inorganic insulation technology, made without any polymer, can push this thermal limit up to 500°C. After presenting an overview of the available HT° insulation technologies, the paper details the possible topologies of HT° machines and their limits.

The objective of this study was to build a set of structural and isopach maps of seismic sequences, seismic-geological sections, paleo-sections and correlation schemes; structural-tectonic and paleotectonic analysis of Novy Port shaft; to study the influence of tectonic processes and lithological factors on the oil and gas content of Jurassic and Cretaceous sedimentary sequences. It was concluded that the formation of the structural trap of Novy Port field began in Berrias-Aptian, the most intensive growth of the structure occurs in the post-Turonian time due to the upward movement of the basement block.

International audience; The aim of the Iceland Deep Drilling Project is to drill into supercritical geothermal systems and examine their economic potential. The exploratory well IDDP-2 was drilled in the Reykjanes geothermal field in SW Iceland, on the landward extension of the Mid-Atlantic Ridge. The Reykjanes geothermal field produces from a

This paper presents an approach to monitor the dynamic disturbances of a BTA (boring and trepanning association) deep drilling system. High length to diameter ratios are the key characteristic of deep drilling processes compared to conventional drilling applications. Since length to diameter ratios of up to 150 for slender tool-boring-bar assemblies are common, the deep drilling process is sensitive to dynamic disturbances such as chatter and whirling vibrations. Whirling vibrations usually effect the shape of the hole and cause holes with several lobes. To gain a deeper understanding of the dynamic state of the process, a sensor application has been developed and was tested in practice. Experimental investigations on BTA deep drilling with continuous multi-sensory monitoring were conducted. The used setup allowed the determination of the frequencies of chatter and whirling vibrations during the cutting process by analysing the logged data using a continuous short-time Fourier transformation (STFT).

The paper by De Natale et al. (2016, https://doi.org/10.1002/2015GC006183) reported new stratigraphic and geochronological data for a borehole located at Campi Flegrei volcanic area. The authors failed to mention several significant articles on the geological evolution of the region and proposed an interpretation of their data according to the caldera model. Herein, we provide tectonic and stratigraphic data to support a fault model of ignimbrite emission. This comment will also show the inconsistency of the proposed Campi Flegrei caldera.

The phenomenon of core disking is commonly seen in deep drilling of highly stressed regions in the Earth’s crust. Given its close relationship with the in situ stress state, the presence and features of core disking can be used to interpret the stresses when traditional in situ stress measuring techniques are not available. The core disking process was simulated in this paper using the three-dimensional discrete element method software PFC3D (particle flow code). In particular, PFC3D is used to examine the evolution of fracture initiation, propagation and coalescence associated with core disking under various stress states. In this paper, four unresolved problems concerning core disking are investigated with a series of numerical simulations. These simulations also provide some verification of existing results by other researchers: (1) Core disking occurs when the maximum principal stress is about 6.5 times the tensile strength. (2) For most stress situations, core disking occurs from the outer surface, except for the thrust faulting stress regime, where the fractures were found to initiate from the inner part. (3) The anisotropy of the two horizontal principal stresses has an effect on the core disking morphology. (4) The thickness of core disk has a positive relationship with radial stress and a negative relationship with axial stresses.

Supercritical geothermal development method has been proposed to increase the use of geothermal resources; the associated challenges include high temperatures and pressures, as well as an acidic environment, which increase the corrosion rate of casing materials. Here, we estimated material corrosion rates assuming that the temperature and pressure in a developmental environment were 500 °C and 60 MPa, respectively. Wells WD-1a in the Kakkonda geothermal field, Japan, and Icelandic Deep Drilling Program-1 (IDDP-1) were used as model cases for the concentrations of volcanic gasses. Geochemical calculations were conducted to obtain distributions of pH values from room temperature to 500 °C at 60 MPa. Corrosion rate distributions for the metallic materials were derived for the temperature recovery period after drilling and production and post-production periods inside the well. Consequently, the pH remained approximately constant at temperatures ≤ 300 °C and increased as the temperature exceeded 300 °C. In the supercritical temperature and pressure region, the pH increased as the pressure decreased, and it maximized at a 0.35 g/cm3 fluid density. The IDDP-1 model exhibited lower pH values than the WD-1a model; the H2S/CO2 ratio and HCl gas also increased. Furthermore, from room temperature to 300 °C, the corrosion rates were found to increase with the temperature and maximized in the subcritical regions at 300–350 °C. The corrosion rates then decreased as the temperature increased in the supercritical temperature regions. In the possible developmental processes, the corrosion rates tended to be high at temperature of 300–350 °C (~2,000 m) during the temperature recovery period after drilling, whereas the corrosion rates tended to increase near the wellhead during fluid production. The corrosion rate maximized near the wellhead immediately after the production period ceased at a well depth of 1,000–1,500 m the following week.

It has been almost fifty years that the so called Bazhenov suite anomalous sections, i.e. formations distinguished by sandy-aleuritic inclusions in Bazhenov bituminous clay attract the wide range of geologists and geophysicists who circulate innumerable, often exotic assumptions concerning generation of anomalous sections. Integrated analysis of mixed geological and geophysical data on anomalous sections formation proved that the initial definition of the former as submarine landslide dislocation by K. I. Mikulenko and G. B. Ostry remains most accurate.

The Koyna region located in the west coast of India is a classic example of reservoir triggered seismicity (RTS) that started soon after the impoundment of the Koyna reservoir in 1962. Previous studies have shown that RTS can be explained in terms of stress and pore pressure changes due to poroelastic response of the rock matrix. The permeability of rock matrix is a key parameter for pore pressure diffusion which is mainly responsible for generation of stress perturbation related to seismicity. Based on the poroelastic theory, we employ 2-D finite element models to simulate the evolution of pore pressure up to 5 years after the reservoir impoundment in 1962, using a range in permeability, 10−16–10−14 m2. Constraints on material properties of Deccan basalt and granitic rocks were taken from available studies. The results show the formation of pore pressure front and its propagation with depth and time since the reservoir impoundment as a function of permeability. While a permeability of 10−16 m2 does not produce any significant change in pore pressure, a ten-fold increase in permeability produces significant changes up to a depth of 2 km only beneath the reservoir after 5 years of impoundment. Permeability values between 10−15 m2 and 10−14 m2 are required to induce critical pore pressure changes in the range 0.1–1 MPa up to depth of 10 km, capable of triggering earthquakes in a critically stressed region. Studies on core samples of granitic basement rock down to a depth of 1522 m in the Koyna region provide evidences of fracture zones that may contribute to water channelization. Direct measurements of material properties through the ongoing deep drilling programme would help to develop more realistic models of RTS.

The 1967 M6.3 earthquake near the Koyna dam produced a surface rupture zone following a NNE-SSW structural trend. The rupture zone is documented in a report by the officers of the Geological Survey of India (GSI, 1968). The surface expressions of the rupture comprising fissures, en-echelon fractures, oblique or diagonal tensional cracks and mole tracks, termed here as the Koyna Fissure Zone (KFZ), were reported over a limited area, about 1000m in length and 200 m in width, located to the southeast of the Koyna dam between Donichawadi and Kadoli. The Koyna region was revisited recently for investigating the fissures, to help in locating potential sites for scientific deep drilling. Most of the reported surface deformation features are obliterated due to intense weathering and laterization of the exposed basalt surface during the past 48 years. However, careful field investigations in the Donichawadi-Kadoli area as well as in the surrounding region show that fissures and fractures are still preserved at several locations. The fissures trend between N30°W to N50°E, similar to that reported previously. The mean orientation of these fissures is 25°/89°-E. Transposition of one set of fissures by another set provide strong evidence for repeated brittle deformation in the area. Physical and microstructural studies on core samples of granite-gneiss basement rock underlying Deccan basalt in the area, obtained from a 1522 m deep borehole at Rasati, confirm the extension of the surface fissures to depth. Occurrences of secondary mineralization along these fissures indicate the percolation of water through fractures within basement granitoids. The evidences for water channelization may have direct implications for the occurrence of reservoir triggered earthquakes in the Koyna region for the past five decades.

To achieve safety, high quality, and efficiency in deep drilling, it is necessary to get formation drillability around the borehole during drilling-trajectory planning and intelligent drilling control. Since the drilling data have the characteristics of low value density and noise in the process of deep drilling, it is difficult to model formation drillability in deep drilling. In this paper, a new online modeling method for formation drillability based on online sequential nadaboost extreme learning machine (OS-Nadaboost-ELM) algorithm has been proposed. Firstly, the well logging parameters are chosen as the inputs of the model, whose output is formation drillability. Then, several ELM models are established and the outputs of these models are as weak learners. Then the weak learners are combined by Nadaboost algorithm in order to get a strong learner. Finally, the recursive least squares algorithm is used to adjust the model. The numerical test results show that, in both prediction accuracy and training efficiency aspects, the proposed method is better than other prediction methods such as multiple regression, gray method, back-propagation neural networks, Nadaboost extreme learning machine and online sequential extreme learning machine. Thus the prediction model serves as the online geological model to develop intelligent drilling systems.

Water properties change with confinement within nanofilms trapped between natural charged clay particles. We investigated nanofilm characteristics through high-stress laboratory compression tests in combination with analyses of expelled pore fluids. We utilized sediments obtained from deep drilling of the Nankai subduction zone at Site C0002 of the Integrated Ocean Drilling Program (IODP). We show that below 1–2 km, there should be widespread ultrafiltration of migrating fluids. Experiments to > ∼ 100 MPa normal compression collapse pores below a few ion monofilm thicknesses. A reduction towards a single condensing/dehydrating ion monofilm occurs as stresses rise >100–200 MPa and clay separations are reduced to

This chapter is compiled in accordance with the article “The Origin, Development and Westward Spread of Chinese Deep Well Drilling Technology”, which was written by Pan Jixing and published in History of Salt Industry, 2009, (4): pp. 3–33.

Summary Acoustic Emission (AE) based systems have been under development and used at Fraunhofer IEG to monitor, evaluate, and control conventional and novel drilling processes and their pertinent equipment used in geothermal and drilling applications. Moreover, novel jetting and drilling operations in deep geothermal reservoirs do heavily rely on such new technologies in order to be able to control them properly and thus, to result in a viable technical and economical option. AE monitoring is based on the detection and conversion of elastic waves into electrical signals, which are associated with a rapid release of localized stress-energy propagating within a material. It is passive testing, logging, and analysis method to evaluate changes in the properties and behavior of machines and mineral type materials such as rocks. Such changes may be induced by drilling, jetting, or other drilling methods and being recorded, characterized, and evaluated via an AE system and will be used ultimately used for process performance prediction using machine learning methods. This is the core of the novel monitoring system development, the AE based, so-called Multi-Sensor acoustic parameter analysis as the primary control and monitoring mechanism during rock breaking, drilling, jetting, and stimulation.