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We have developed a case study of geophysical reservoir characterization in which we use elastic inversion and probabilistic prediction to estimate nine carbonate lithofacies and the associated porosity distribution. The study focuses on an isolated carbonate platform of middle Miocene age, offshore Sarawak in Malaysia that has been partly dolomitized — a process that increased the porosity and permeability of the prolific gas reservoir. The nine lithofacies are defined from one reference core and include a range of lithologies and pore types, covering limestone and dolomitized limestone, each with vuggy varieties, as well as sucrosic and crystalline dolomites with intercrystalline porosity, and argillaceous limestones and shales. To predict the lithofacies and porosity from geophysical data, we adopt a probabilistic algorithm that uses Bayesian theory with an analytical solution for conditional means and covariances of posterior probabilities, assuming a Gaussian mixture model. The inversion is a two-step process, first solving for P- and S-wave velocities and density from two partial seismic stacks. Subsequently, the lithofacies and porosity are predicted from the elastic parameters in the borehole and across a 2D inline. The final result is a model that consists of the pointwise posterior distributions of the facies and porosity at each location where seismic data are available. The facies posterior distribution represents the facies proportions estimated from seismic data, whereas the porosity distribution represents the probability density function at each location. These distributions provide the most likely model and its associated uncertainty for geologic interpretations of lithofacies associated with distinct stages of carbonate platform growth.

Nature Communications 7: Article number: 13040 (2016); Published: 10 October 2016; Updated: 30 August 2017 This Article contains typographical errors in Fig. 3 and Equation 23. In Fig. 3c, the labels ‘12C’ and ‘13C’ in the key should be reversed. The correct version of Fig. 3 appears below as Fig. 1.

We documented arroyo evolution at the tree, trench, and arroyo scales along the lower Rio Puerco and Chaco Wash in northern New Mexico, USA. We excavated 29 buried living woody plants and used burial signatures in their annual rings to date stratigraphy in four trenches across the arroyos. Then, we reconstructed the history of arroyo evolution by combining trench data with arroyo-scale information from aerial imagery, light detection and ranging (LiDAR), longitudinal profiles, and repeat surveys of cross sections. Burial signatures in annual rings of salt cedar and willow dated sedimentary beds greater than 30 cm thick with annual precision. Along both arroyos, incision occurred until the 1930s in association with extreme high flows, and subsequent filling involved vegetation development, channel narrowing, increased sinuosity, and finally vertical aggradation. A strongly depositional sediment transport regime interacted with floodplain shrubs to produce a characteristic narrow, trapezoidal channel. The 55 km study reach along the Rio Puerco demonstrated upstream progression of arroyo widening and filling, but not of arroyo incision, channel narrowing, or floodplain vegetation development. We conclude that the occurrence of upstream progression within large basins like the Rio Puerco makes precise synchrony across basins impossible. Arroyo wall retreat is now mostly limited to locations where meanders impinge on the arroyo wall, forming hairpin bends, for which entry to and exit from the wall are stationary. Average annual sediment storage within the Rio Puerco study reach between 1955 and 2005 was 4.8 × 10 5 t/yr, 16% of the average annual suspended sediment yield, and 24% of the long-term bedrock denudation rate. At this rate, the arroyo would fill in 310 yr.

Elastic shear moduli from ultrasonic measurements of carbonate rocks show an increase or decrease when saturated from the dry state with brine. The induced changes on the moduli have been attributed to several rock-fluid interaction effects, including viscous coupling, reduction in free surface energy, and dispersion caused by local flow with a subsequent effect on acoustic velocities. As many studies have recognized that acoustic velocity in carbonate rocks is dependent on pore structure, a relationship between the pore structure and observed changes must, to a certain extent, exist. We make use of quantitative digital image analysis parameters, such as dominant pore size and perimeter over area, to demonstrate how changes in dynamic shear moduli upon saturation relate to the geologic make up of the rock. Samples with a small dominant pore size and large perimeter over area show abnormal decrease in shear moduli with saturation from the dry state. This is attributed to the large surface area available for matrix-fluid interaction. Samples with large dominant pore size and small perimeter over area show an increase in shear moduli with saturation. This may be a dispersion effect, as high frequency and high permeability may cause the fluid in the saturated samples to move out-of-phase with the solid during propagation of the acoustic wave and thus cause a stiffening effect.

Carbonate rocks commonly contain a variety of pore types that can vary in size over several orders of magnitude. Traditional pore-type classifications describe these pore structures but are inadequate for correlations to the rock's physical properties. We introduce a digital image analysis (DIA) method that produces quantitative pore-space parameters, which can be linked to physical properties in carbonates, in particular sonic velocity and permeability. The DIA parameters, derived from thin sections, capture two-dimensional pore size (DomSize), roundness (), aspect ratio (AR), and pore network complexity (PoA). Comparing these DIA parameters to porosity, permeability, and P-wave velocity shows that, in addition to porosity, the combined effect of microporosity, the pore network complexity, and pore size of the macropores is most influential for the acoustic behavior. Combining these parameters with porosity improves the coefficient of determination (R2) velocity estimates from 0.542 to 0.840. The analysis shows that samples with large simple pores and a small amount of microporosity display higher acoustic velocity at a given porosity than samples with small, complicated pores. Estimates of permeability from porosity alone are very ineffective (R2 = 0.143) but can be improved when pore geometry information PoA (R2 = 0.415) and DomSize (R2 = 0.383) are incorporated. Furthermore, results from the correlation of DIA parameters to acoustic data reveal that (1) intergrain and/or intercrystalline and separate-vug porosity cannot always be separated using sonic logs, (2) P-wave velocity is not solely controlled by the percentage of spherical porosity, and (3) quantitative pore geometry characteristics can be estimated from acoustic data and used to improve permeability estimates.

To assess saturation effects on acoustic properties in carbonates, we measure ultrasonic velocity on 38 limestone samples whose porosity ranges from 5% to 30% under dry and water-saturated conditions. Complete saturation of the pore space with water causes an increase and decrease in compressional- and shear-wave velocity as well as significant changes in the shear moduli. Compressional velocities of most water-saturated samples are up to [Formula: see text] higher than the velocities of the dry samples. Some show no change, and a few even show a decrease in velocity. Shear-wave velocity [Formula: see text] generally decreases, but nine samples show an increase of up to [Formula: see text]. Water saturation decreases the shear modulus by up to [Formula: see text] in some samples and increases it by up to [Formula: see text] in others. The average increase in the shear modulus with water saturation is [Formula: see text]; the average decrease is [Formula: see text]. The [Formula: see text] ratio shows an overall increase with water saturation. In particular, rocks displaying shear weakening have distinctly higher [Formula: see text] ratios. Grainstone samples with high amounts of microporosity and interparticle macro-pores preferentially show shear weakening, whereas recrystallized limestones are prone to increase shear strengths with water saturation. The observed shear weakening indicates that a rock-fluid interaction occurs with water saturation, which violates one of the assumptions in Gassmann’s theory. We find a positive correlation between changes in shear modulus and the inability of Gassmann’s theory to predict velocities of water-saturated samples at high frequencies. Velocities of water-saturated samples predicted by Gassmann’s equation often exceed measured values by as much as [Formula: see text] for samples exhibiting shear weakening. In samples showing shear strengthening, Gassmann-predicted velocity values are as much as [Formula: see text] lower than measured values. In 66% of samples, Gassmann-predicted velocities show a misfit to measured water-saturated P-wave velocities. This discrepancy between measured and Gassmann-predicted velocity is not caused solely by velocity dispersion but also by rock-fluid interaction related to the pore structure of carbonates. Thus, a pore analysis should be conducted to assess shear-moduli changes and the resultant uncertainty for amplitude variation with offset analyses and velocity prediction using Gassmann’s theory.

The elastic moduli of a rock are affected by three main factors: pore fluid, rock framework, and pore space. In carbonate rocks, the latter two factors are a function of the depositional environment and the diagenetic history. Cementation, recrystallization, and dissolution processes can change the mineralogy and texture of the original framework and thereby alter the original grain-to-grain contacts and/or occlude pore space. Dissolution processes can enlarge interparticle pore space or dissolve grains entirely, thereby increasing porosity. These diagenetic alterations and associated changes in the rock frame and pore structure result in a wide velocity range at a given porosity.

We present a method for predicting permeability from sonic and density data. The method removes the porosity effect on the ratio [Formula: see text] of dry rock, and it addresses the specific surface as an indirect measure of permeability. We look at ultrasonic data, porosity, and the permeability of 114 carbonate core plugs. In doing so, we establish an empirical relationship between the specific surface of the solid phase (as calculated by Kozeny’s equation) and [Formula: see text] (linearly transformed to remove the porosity effect). One must view the specific surface derived by using Kozeny’s equation as an effective specific surface because Kozeny’s equation only holds for homogeneous rock with interconnected pores. The ratio [Formula: see text] of dry rocks, on the other hand, seems to be controlled by the true specific surface, pointing to an inherent limitation in the method. The 114 carbonate plugs originate in three geological settings and comprise 83 calcitic and 31 dolomitic samples. Their depositional texture varies from mud-dominated to grain-dominated and recrystallized types. Our research applies the relationship to 137 carbonate samples from two different depositional settings. We find a reasonable match between predicted and measured permeability. The match is better for samples with carbonate mud-filled depositional textures than for carbonate mud-poor depositional textures. Diagenetic factors such as vuggy porosity decrease the predictability of permeability.

This paper reports a series of 700 porosity–permeability analyses and supporting petrographic and sedimentologic descriptions from Early to Late Miocene carbonate strata cored on the Marion Plateau, offshore from north-eastern Australia, during Ocean Drilling Program (ODP) Leg 194. The samples analysed are not only mainly coarse bioclastic limestones and dolomitized equivalents from platform-top facies, but also include 79 plugs from deeper-water slope to hemipelagic drift facies. Outstanding characteristics of this data set are the wide ranges of porosity and permeability in both limestones and dolostones, the large degree of short-range heterogeneity typical of these strata, and the better porosity–permeability correlation of dolostones than limestones. The platforms have experienced widely varying calcite cementation, dolomitization and dissolution but show little clear evidence of meteoric diagenesis, suggesting that subaerial exposure may have played little role in porosity–permeability evolution. Permeability-for-given-porosity is controlled by grain size and calcite cement content in grainstones and by occurrence of larger shelter pores and vugs in mud-rich samples. Dolomitization tends to reduce the variation of permeability-for-given-porosity by recrystallizing mud matrix to form intercrystalline macroporosity that connects vugs and moulds to become integrated with the effective pore system. As a result, there are no differences in permeability–porosity trends for different dolostone textures, whether dominated by intercrystalline, vuggy, or preserved intergranular pore types. Two platform-top sites separated by only 5 km display a major lateral variation in dolostone porosity–permeability characteristics within the youngest dolostone units. This difference is interpreted as reflecting a relatively ‘windward’ (current-facing) setting of the site with the overall higher permeability-for-given-porosity (Site 1199) that led to less muddy depositional facies, greater cementation, and lesser grain dissolution. Pore-geometry parameters measured by petrographic image analysis confirm that the ‘windward’ dolostones have pores that are both larger and less intricate than dolostones comprising the more current-protected location.

In laboratory experiments we measured the saturation effects on the acoustic properties in carbonates and the results question some theoretical assumptions. In particular, these laboratory experiments under dry and wet conditions show that shear moduli do not remain constant during saturation. This change in shear modulus puts Gassmann's assumption of a constant shear modulus into question and also explains why velocities predicted with the Gassmann equation can be lower or higher than measured velocities.

Carbonate sediments are prone to rapid and pervasive diagenetic alterations that change the mineralogy and pore structure within carbonate rocks. In particular, cementation and dissolution processes continuously modify the pore structure to create or destroy porosity. In extreme cases these modifications can completely change the mineralogy from aragonite/calcite to dolomite, or reverse the pore distribution whereby original grains are dissolved to produce pores as the original pore space is filled with cement to form the rock (Figure 1). All these modifications alter the elastic properties of the rock and, therefore, the sonic velocity. The result is a dynamic relationship among diagenesis, porosity, pore-type, and sonic velocity. The result is a wide range of sonic velocity in carbonates, in which compressional-wave velocity (VP) ranges from 1700 to 6600 m/s and shear-wave velocity (VS) from 600 to 3500 m/s.

The response of rivers and riparian forests to upstream dams shows a regional pattern related to physiographic and climatic factors that influence channel geometry. We carried out a spatial analysis of the response of channel geometry to 35 dams in the Great Plains and Central Lowlands, USA. The principal response of a braided channel to an upstream dam is channel-narrowing, and the principal response of a meandering channel is a reduction in channel migration rate. Prior to water management, braided channels were most common in the southwestern Plains where sand is abundant, whereas meandering channels were most common in the northern and eastern Plains. The dominant response to upstream dams has been channel-narrowing in the southwestern Plains (e.g., six of nine cases in the High Plains) and reduction in migration rate in the north and east (e.g., all of twelve cases in the Missouri Plateau and Western Lake Regions). Channel-narrowing is associated with a burst of establishment of native and exotic woody riparian pioneer species on the former channel bed. In contrast, reduction in channel migration rate is associated with a decrease in reproduction of woody riparian pioneers. Thus, riparian pioneer forests along large rivers in the southwestern Plains have temporarily increased following dam construction while such forests in the north and east have decreased. These patterns explain apparent contradictions in conclusions of studies that focused on single rivers or small regions and provide a framework for predicting effects of dams on large rivers in the Great Plains and elsewhere. These conclusions are valid only for large rivers. A spatial analysis of channel width along 286 streams ranging in mean annual discharge from 0.004 to 1370 cubic meters per second did not produce the same clear regional pattern, in part because the channel geometries of small and large streams are affected differently by a sandy watershed.

Abstract Determination of porosity, hydrocarbon saturation and net reservoir thickness in unconventional shale oil and gas reservoirs is often a major petrophysical challenge due to the low porosities typically present in these reservoirs and the impact of kerogen on fundamental rock properties such as the grain density, porosity and permeability. The challenge is large in emerging play areas where core measurements are limited or not available, and quality information on total organic carbon (TOC) content and mineralogy may be sparse. Legacy wireline logging measurements such as Resistivity, Gamma Ray, Density, and Sonic are often the primary source of rock property information. Deriving accurate ranges for key volumetric parameters is essential for risking and assessing an economic value for these plays. Also important for assessing economic value is predicting the effectiveness of fracture stimulation to achieve expected ultimate recoveries (EUR's) that are economically attractive. This requires interpretations of the mechanical properties of the reservoir. The petrophysical characterization for emerging plays can be enhanced by utilization of analog core based trends as well as learnings gained from developing and mature plays. This paper focuses on the use of analogs to improve the petrophysical characterization in emerging plays where uncertainties are generally large. Introduction The petrophysical evaluation of shale oil and gas reservoirs in emerging play areas is often very challenging. As in most shale oil and gas reservoirs, a basic understanding of the matrix lithological components, clay content, kerogen content, and maturity level is required for deriving reasonable ranges in key volumetric parameters such as the porosity, hydrocarbon saturation and net reservoir thickness. In emerging play areas, legacy wireline logging measurements such as Resistivity, Gamma Ray, Density, and Sonic are often the primary source of rock property information. Core measurements are limited or not available, and quality information on TOC and mineralogy may be sparse. As such, the volumetric parameters can have very large uncertainties. To reduce or manage these uncertainties, it is important to leverage data and learnings from developing and mature plays where there may be an extensive knowledge base of log and core data. This paper outlines a workflow for developing and using analog trends to improve the petrophysical evaluation in these challenging emerging plays.

The effects of river regulation on bottomland tree communities in western North America have generated substantial concern because of the important habitat and aesthetic values of these communities. Consideration of such effects in water management decisions has been hampered by the apparent variability of responses of bottomland tree communities to flow alteration. When the relation between streamflow and tree establishment is placed in a geomorphic context, however, much of that variability is explained, and prediction of changes in the tree community is improved. The relation between streamflow and establishment of bottomland trees is conditioned by the dominant fluvial process or processes acting along a stream. For successful establishment, cottonwoods, poplars, and willows require bare, moist surfaces protected from disturbance. Channel narrowing, channel meandering, and flood deposition promote different spatial and temporal patterns of establishment. During channel narrowing, the site requirements are met on portions of the bed abandoned by the stream, and establishment is associated with a period of low flow lasting one to several years. During channel meandering, the requirements are met on point bars following moderate or higher peak flows. Following flood deposition, the requirements are met on flood deposits ;high above the channel bed. Flood deposition can occur along most streams, but where a channel is constrained by a narrow valley, this process may be the only mechanism that can produce a bare, moist surface high enough to be safe from future disturbance. Because of differences in local bedrock, tributary influence, or geologic history, two nearby reaches of the same stream may be dominated by different fluvial processes and have different spatial and temporal patterns of trees. We illustrate this phenomenon with examples from forests of plains cottonwood (Populus deltoides ssp. monilifera) along meandering and constrained reaches of the Missouri River in Montana.

Abstract Summary Limestone and dolomite reservoirs account for approximately 50% of oil and gas production worldwide, yet seismic responses in carbonate rocks are poorly understood. Development of a carbonate rock physics model is extremely difficult because pore systems are more complex in carbonates than they are in clastics. Carbonates can have a variety of pore types, such as moldic, vuggy, interparticle, and intraparticle. The complex pore system creates significant scatter in the porosity-velocity relationship, as indicated in experimental results (e.g., Anselmetti and Eberli, 2001). Pore shape appears to be the dominant factor in carbonate rock physics. Moldic, intraframe, and vuggy pores tend to be rounded and make the rock stronger (faster) than when the pores are interparticle. Micro pores (e.g., microcracks) tend to be flat and make the rock weaker. To effectively characterize carbonate reservoir rocks, it is critical to develop a rock physics model capable of handling different pore types. In addition to pore types and pore shapes, other factors need to be included in a physics-based rock model. Some specific additional factors are lithology and grain shapes, multiphase fluids and wetting effects, rock-fluid interactions (poro-elasticity), stress effects, anisotropy, heterogeneity and scale effects, chemical changes to the framework, and corrections for environmental effects due to logging conditions. Any rock physics model should be calibrated and validated with controlled laboratory experiments, field measurements, and computational rock physics. In this paper, we demonstrate the impact and validation of several of these factors. Carbonate Rock Physics Model We prefer an analytical rock physics model rather than empirical ones due to both the predictive power that it provides without having to acquire so much analog data and its physics-based nature. Empirical rock physics models are widely used due to their simplicity in fitting a relationship between parameters. The advantage of an analytical model is that once the parameters describing the physical controlling factors are determined, the model can be applied anywhere that the controlling parameters can be estimated. This achieves better predictions and deeper understanding of the subsurface than empirical models with less data. Nonlinear physics-based inclusion models (e.g., Kuster and Toksoz, 1974) are attractive because they handle various factors that impact seismic response in an internally consistent manner.

Abstract Summary We demonstrate the application of rock physics as the linchpin in inverting geophysical measurements for properties that govern hydrocarbon volumes and production rates. The importance of having internally consistent rock physics models is essential for quantitative seismic inversion. This paper also highlights many of the effects that need to be incorporated into an analytical rock physics model. Some of the applications include improved reservoir characterization in carbonates, use of rock physics in 4-D analyses and interpretation, and validation with computational rock physics. We first describe the inversion process and the requirements for generating an earth model or models containing engineering and geologic rock and fluid properties. We will discuss extending the Xu-White (1995) rock physics model to carbonate rocks. We will then demonstrate pore type inversion by fitting Vp and Vs data simultaneously to the carbonate rock physics model to invert for either crack pore volume fractions or stiff pore volume fractions. Rock Physics Modeling When inverting geophysical data, the primary goal is to predict engineering and geologic properties that describe hydrocarbon volumes and the rate at which we can produce reservoirs. These properties include porosity, lithology (often indicated by Vshale), water saturation, permeability, pore type and shape, stress state, and others. A crucial step in this process is the development of internally consistent rock physics models that must be used to convert from geophysical data to these properties. The development of a carbonate rock physics model is extremely difficult because carbonate pore systems are more complex than they are in clastics. Carbonates can have a variety of pore types, such as moldic, vuggy, interparticle, intraparticle and micro pores. The complex pore system creates significant scatter in the porosity velocity relationship, as indicated in experimental results (e.g., Anselmetti and Eberli, 2001). Pore shape appears to be the dominant factor in carbonate rock physics. Moldic, intraframe, and vuggy pores tend to make the rock stronger (faster) than rocks dominated by interparticle porosity. Micro pores (e.g., microcracks) tend to be flat and make the rock weaker. To effectively characterize carbonate reservoir rocks, it is critical to develop a rock physics model capable of handling different pore types. In addition to the size and shape of pores, other factors need to be included in a physics-based rock model. Some specific additional factors are lithology and grain shapes, multiphase fluids and wetting effects, rock-fluid interactions (poro-elasticity and chemical changes to the framework), stress effects, anisotropy, heterogeneity and scale effects, and corrections for environmental effects due to logging conditions. Any rock physics model should be calibrated and validated with controlled laboratory experiments, field measurements, and computational rock physics.

Summary In order to model the effect of oil/gas production or CO2 injection at the seismic scale, we have to understand the effects of pore structure, pressure and fluid changes on velocity at the laboratory scale. To reach this goal, we measured carbonate rocks with a suite of miscible fluids, simulating the entire range of reservoir fluid moduli from light to heavy oils. In our experiments, compressional velocity (Vp) and shear wave velocity (Vs) are simultaneously measured at a frequency of 1MHz and under increasing effective stress from 3 MPa to 30 MPa. We observe large variations in velocities between 3200 m/s and 6500 m/s and a large scatter in the P-wave velocity – porosity relationship. The P-wave velocity shows up to 2000m/s difference at a given porosity. The velocity increases between 250 and 750m/s as pressure incresases from 3 to 30MPa. The bulk of the samples show increasing Vp/Vs ratios with pressurization, up to values between 1.7 and 1.84. The ratio of normalized bulk versus shear modulus ranges from 0.7 to 0.9. Twenty-one oomoldic carbonate samples with nearly spherical pores show a weak correlation between velocity and porosity under dry conditions. We attribute the weak correlation between velocity and porosity in rocks with similar pore geometry to variations in inter-crystalline porosity in the rock frame. This finding questions the assumption that spherical pores have a dominant effect on velocity. Four oomoldic samples were chosen for fluid substitution and saturated “in-situ” with seven different pore fluids. Significant effects of fluid changes on velocity are observed. A linear correlation exists between bulk modulus and fluid modulus (r 2 > 0.97). In contrast, shear modulus changes correlated with the viscosity of the fluids: the lower the fluid viscosity, the lower the shear modulus. Our results question common hypotheses for modeling pore-structure effects on acoustic properties in carbonates; (a) P-wave velocity is controlled by the percentage of spherical porosity, and (b) the P-wave velocity in oomoldic rocks is insensitive to fluid and pressure changes because of high stiffness of the rock frame. These findings imply that one has to be cautious in relating rock-physics model parameters to volumetric dominant pore types.

Elastic moduli of water saturated sedimentary rocks have in some cases been found to be lower than what would be expected from Gassmann-substitution of moduli for rocks in the dry state, Such water weakening of elastic moduli of carbonate sedimentary rocks may be discussed by effective medium modeling. In the present case we use the isoframe model, which is based on upper HashinShtrikman bounds for mixtures of a stiff carbonate frame and a suspension of carbonate particles in fluid. The proportion of carbonate in the frame is given as the iso-frame value ranging from zero to one. We model ultrasonic compressional wave and shear wave data for dry and water saturated samples from a range of geological settings. Our modeling indicates that water weakening is related to permeability. Samples with permeability up to 1 mD have relatively high water weakening possibly as a consequence of fluid interaction with the relatively frequent crystal contacts in the low-permeability samples. For samples with permeability above 100 mD we rather find a stiffening of water saturated samples. This may be a dispersion effect, as high permeability and high frequency may cause the water in the water saturated samples to move out of phase with the solid during propagation of the sonic wave and thus cause a stiffening effect.

This reference is for an abstract only. A full paper was not submitted for this conference. Abstract Shell's Carbonate Team has been developing a method in which post-stackseismic can be used to estimate average interval matrix permeability incarbonates. The foundation of the technique is a new model, which describes quantitative relationships between sonic velocity, porosity and permeability. This model relates a pore shape factor from the poro-elasticity theory with permeability from lab measurements. This pore shape factor describes the 3Dpore structure and can be extracted from inverted post-stack seismic data. Additionally, this factor relates to pore connectivity and, therefore, to permeability. After the concept was tested and successfully proven on plug scale, the first implementation focused on a large carbonate field in the Middle East. This accumulation had all the ingredients to perform a full field test of the concept - good thickness for multiple seismic reflections, matrix-dominated permeability, single mineralogy (calcite), superb seismic data and enough wells with good compressional and shear sonic logs. Introducing pore structures in the characterisation of carbonate reservoirs from acoustic data helps resolve the ambiguity in porosity/permeability prediction. In the test case, we have demonstrated that: the new rock property prediction is much more accurate than properties predicted by commercial inversion packages,pore structure can be extracted from 3- Dpost-stack seismic,a permeability indicator can be estimated from inverted seismic anda permeability indicator volume proved to produce a superior history match against a permeability model constructed from extensive welldata

Velocity – porosity transforms and porosity – permeability transforms are frequently used for upscaling of rock properties from core and log scale to reservoir scale. Carbonate rocks often show a large scatter in the relationship between porosity and permeability. Hence further analyses are required in order to better predict permeability, which would result in more accurate reservoir modeling, and better reserve predictions. Incorporating image analysis enables us to reduce the uncertainties present in velocity and permeability scatter. Obtaining the microporosity by subtracting the macroporosity from the plug porosity leads to a better correlation with velocity than total porosity. The trend follows the Wyllie time average trend line. The deviation between measured total porosity and microporosity, the image macroporosity, is an excellent indicator of permeability in our dataset. Using the image macroporosity versus permeability trend reduces the uncertainty of permeability prediction by more than one order of magnitude. In our case, the microporosity is the dominant ineffective porosity for fluid flow. This reduction in uncertainty allows for better reservoir prediction and development.