Stochastic workflow for geological fault seal analysis in carbonate-hosted reservoirs

Abstract

Certain aspects of the disclosure provide a method for fault seal analysis. The method generally includes identifying a fault plane in a subsurface model; determining a plurality of facies juxtaposition types for the fault plane; estimating a fault rock permeability range for each facies juxtaposition type; generating a plurality of candidate fault plane permeability scenarios, wherein for each candidate fault plane permeability scenario, a candidate fault plane permeability property is assigned to each facies juxtaposition type using a simulation and the fault rock permeability range estimated for the respective facies juxtaposition type; and for each candidate fault plane permeability scenario of one or more candidate fault plane permeability scenarios of the plurality of candidate fault plane permeability scenarios, determining fault seal property(ies) for the fault plane using the candidate fault plane permeability properties assigned to the plurality of facies juxtaposition types for the respective candidate fault plane permeability scenario.

Description

STOCHASTIC WORKFLOW FOR GEOLOGICAL FAULT SEAL ANALYSIS IN CARBONATE-HOSTED RESERVOIRSBACKGROUNDField

[0001] Aspects of the present disclosure relate to fault seal analysis.Description of Related Art

[0002] Geological faults have the potential to act as seals in hydrocarbon reservoirs, withholding large fluid volumes over geological and production timescales. Specifically, a fault (also referred to herein as a “fault plane”) is a break or planar surface in brittle rock across which there is observable displacement. Some fault surfaces contain relatively coarse rubble that can act as a conduit for migrating oil or gas, whereas the surfaces of some other faults are smeared with relatively impermeable rock, commonly shale (e.g., a fine-grained, fissile, detrital sedimentary rock formed by consolidation of clay- and silt-sized particles into thin, relatively impermeable layers), anhydrite, and / or salt, that may act as a fault seal. For example, the impermeable rock may form a barrier or cap above and / or around reservoir rock to help prevent the migration of fluids, including hydrocarbons (e.g., such as natural gas and oil), beyond the reservoir.

[0003] Understanding the behavior of a fault to act as a transmitter of or a barrier to fluid flow is useful for hydrocarbon drilling, exploration, and / or development. Accordingly, fault seal analyses have been developed to predict fault behavior and to reduce uncertainty and risk in faulted reservoir exploitation. For example, such analyses may help to (1) understand the risk of hydrocarbons leaking out a fault trap (e.g., a trap where closure is controlled by the presence of at least one fault surface) across bounding faults and / or (2) understand how fault(s) influence the behavior of a hydrocarbon reservoir during production.

[0004] Although aspects are described herein with respect to the use of fault seals for hydrocarbon capture and storage, in certain aspects, fault seals may also be used to prevent the migration of carbon dioxide when carbon dioxide is stored in deep underground geologic formations for safe, secure, and permanent storage (e.g., for carbon capture and storage (CCS) processes).SUMMARY

[0005] Certain aspects of the disclosure provide a method for fault seal analysis, comprising: identifying at least one fault plane in a subsurface model representing one or more petrophysical properties of a reservoir structure; determining a plurality of facies juxtaposition types for the at least one fault plane, each facies juxtaposition type of the plurality of facies juxtaposition types identifying different facies pairs in contact along the at least one fault plane; estimating a fault rock permeability range for each facies juxtaposition type of the plurality of facies juxtaposition types; generating a plurality of candidate fault plane permeability scenarios, wherein for each candidate fault plane permeability scenario, a candidate fault plane permeability property is assigned to each facies juxtaposition type of the plurality of facies juxtaposition types using a simulation and the fault rock permeability range estimated for each facies juxtaposition type; for each candidate fault plane permeability scenario of one or more candidate fault plane permeability scenarios of the plurality of candidate fault plane permeability scenarios, determining one or more fault seal properties for the at least one fault plane using the plurality of candidate fault plane permeability properties assigned to the plurality of facies juxtaposition types for the respective candidate fault plane permeability scenario; and generating the one or more fault seal properties for the one or more candidate fault plane permeability scenarios for display on a computing device.

[0006] Other aspects provide processing systems configured to perform the aforementioned methods as well as those described herein; non-transitory, computer-readable media comprising instructions that, when executed by a processors of a processing system, cause the processing system to perform the aforementioned methods as well as those described herein; a computer program product embodied on a computer readable storage medium comprising code for performing the aforementioned methods as well as those further described herein; and a processing system comprising means for performing the aforementioned methods as well as those further described herein.

[0007] The following description and the related drawings set forth in detail certain illustrative features of one or more aspects.DESCRIPTION OF THE DRAWINGS

[0008] The appended figures depict certain aspects and are therefore not to be considered limiting of the scope of this disclosure.

[0009] FIGS. 1A-1E depict an example system used to predict fault seal behavior.

[0010] FIG. 2 is an example scatter plot generated for display based on dynamic measures of model connectivity associated with multiple candidate fault plane permeability scenarios.

[0011] FIG. 3 is an example visualization generated for display to depict the predicted transmissibility of multiple fault planes for a candidate fault plane permeability scenario.

[0012] FIG. 4A is an example visualization generated for display to depict predicted fault sealing capacity of a fault plane in a candidate fault plane permeability scenario.

[0013] FIG. 4B is an example visualization generated for display to depict a predicted free water level for high risk locations along a fault plane in a candidate fault plane permeability scenario.

[0014] FIG. 4C is an example visualization generated for display to depict predicted fault rock discontinuity risk for a fault plane in a candidate fault plane permeability scenario.

[0015] FIG. 5 depicts an example method for fault seal analysis.

[0016] FIG. 6 depicts an example processing system on which aspects of the present disclosure can be performed.

[0017] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the drawings. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.DETAILED DESCRIPTION

[0018] Industry-standard workflows created to streamline fault seal analyses have traditionally focused on siliciclastic reservoirs containing siliciclastic sedimentary rocks. Siliciclastic sedimentary rocks are silica-based, noncarbonaceous sediments that are often broken from preexisting rocks, transported elsewhere, and redeposited before forming another rock. Examplesof common siliciclastic sedimentary rocks include conglomerate, sandstone, siltstone, and shale. Fault sealing capacity workflows for such siliciclastic reservoirs traditionally involve building a structural framework of key seismic horizons and faults of a siliciclastic reservoir and estimating the clay content of the stratigraphy. Further, fault clay content is estimated using an algorithm, such as a shale gouge ratio (SGR) or a shale smear factor (SSF). Host rock clay content and fault throw (e.g., where fault throw is the amount of vertical displacement of rocks due to faulting) may be provided as inputs into the algorithm to estimate the fault clay content. The estimated fault clay content is then converted to key flow properties, such as capillary threshold pressure and / or permeability, to calculate sealing capacity(ies) of fault(s) in the siliciclastic reservoir.

[0019] While the aforementioned method provides an efficient and effective practice for predicting fault behavior in the subsurface to help reduce the uncertainty in exploiting faulted reservoirs, the limited nature of the method to siliciclastic reservoirs prevents use of the methodology in other reservoir types, such as carbonate-hosted reservoirs. As used herein, carbonate-hosted reservoirs (or simply “carbonate reservoirs”) refer to reservoirs with carbonate- dominate host rocks, where carbonate rock is a class of sedimentary rock whose chief mineral constituents (e.g., 95% or more) are calcite and aragonite (both CaCCh) and dolomite (CaMg(CO3)2) (e.g., a mineral that may replace calcite during the process of dolomitization). Example carbonate rocks may include limestone, dolomite, dolostone, and chalk, to name a few. Carbonate reservoirs may have only a small clay mineral content (e.g., average clay mineral content of 15% or less). Further, the clay content in carbonate reservoirs may have less variability than a mixed siliciclastic sequence of sandstone and shale, and thus, clay content may not be an important control on flow properties of carbonates, whereas it is for siliciclastics. Accordingly, using fault clay content in carbonate reservoirs to further predict key flow properties, such as capillary threshold pressure and / or permeability, for fault sealing capacity estimation, as done in siliciclastic reservoirs for fault seal analysis, may result in poor prediction performance. Thus, existing methods for performing fault seal analyses may provide misleading and / or inaccurate results for carbonate reservoirs.

[0020] Further, due to the complex geology and heterogeneity of carbonate reservoirs, other methods for fault seal estimation also remain under-explored. In particular, heterogeneity in carbonates may be attributed to variable lithology, chemi stry / mineralogy, pore types, poreconnectivity, and / or variable lithofacies (simply referred to herein as “facies”). These inherent complexities may be related to processes controlling original deposition and subsequent diagenesis (e g., refers to the physical and chemical processes that affect sedimentary materials after deposition and before metamorphism and between deposition and weathering). Such variability in carbonate reservoirs may occur within small sections of the reservoir thereby making it difficult to (1) understand the heterogeneous nature of rock containing fluids and / or (2) understand the flow properties within the porous and fractured formations of carbonate reservoirs for fault seal analysis.

[0021] For example, carbonate depositional environments may produce a diverse range of facies having different properties. As such, faults created in carbonate reservoirs due to rock displacement may result in differing facies juxtaposed along each fault plane, thereby resulting in increased microstructural heterogeneity, in some cases, over short length scales (e g., such as a few meters). Increased microstructural heterogeneity along a fault plane may result in a larger range of possible permeability values (e.g., a range of values typically 5-7 orders of magnitude greater) that may need to be analyzed for fault seal estimation. In addition, host rock porosity, host rock permeability, host rock texture, fault displacement, tectonic regime, and / or burial depth during faulting may also need to be considered when determining the range of possible permeability values to predict. The sheer number of variables and facies to consider, along with their corresponding variability, especially over short length scales in a carbonate reservoir, make prediction of fault rock properties for fault seal analysis a technically challenging task, yet it is needed to holistically and accurately understand the behavior of faults for hydrocarbon drilling, exploration, and / or development.

[0022] Further, the scope of the technical problem associated with predicting fault rock properties in carbonate reservoirs is significant given that a high proportion of the world’s hydrocarbon reserves are found in these reservoirs. For example, by some estimates, more than 60% of the world’s oil and approximately 40% of the world’s gas reserves are held in carbonate reservoirs, yet it is not presently technically feasible to quantitatively and accurately evaluate fault sealing capacity and permeability in such reservoirs, as described above.

[0023] As such, faults and their behavior need to be accurately understood to successfully explore and extract hydrocarbon reserves in carbonate reservoirs. For example, faults that do notform a seal may prevent oil and gas from accumulating as hydrocarbons form and migrate through structures in the subsurface. Alternatively, open and permeable faults within an established reservoir may cause problems during drilling operations, such as the loss of drilling mud. The loss of drilling mud can be expensive and dangerous, and, in some cases, may result in the abandonment of wells.

[0024] Additionally, poor predictions of reservoir behavior during production may lead to unexpected compartmentalization of the reservoir, overestimation of producible reserves, and / or increased drilling costs to produce from fault-bounded compartments. On the other hand, if compartmentalization is predicted but does not occur, producible reserves may be underestimated and unnecessary producer wells may be drilled. Accordingly, there is a need for a technical solution that facilitates the evaluation of fault sealing potential in carbonate reservoirs.

[0025] Embodiments described herein help to overcome the aforementioned technical problems of conventional approaches and improve upon the state of the art by providing a workflow for fault seal estimation in carbonate reservoirs, where the workflow involves combining (1) analysis of cross-fault facies juxtapositions with (2) a stochastic work step to generate candidate fault plane permeability properties, with reasonable values, for fault plane(s) in a carbonate reservoir. For example, workflows described herein generate a subsurface model representing one or more petrophysical properties of a faulted carbonate reservoir structure. The subsurface model may include information (e.g., derived from well data, seismic attribute analysis, outcrop analogues, conceptual depositional models, etc.) about different cross-fault facies juxtaposition types (simply referred to herein as “facies juxtaposition types”) for at least one fault plane in the subsurface model. The workflows described herein further estimate a fault rock permeability range for each facies juxtaposition type along the fault plane and using the estimated fault rock permeability ranges to generate a plurality of candidate fault plane permeability scenarios. For example, a stochastic approach may be used to predict an X amount of feasible fault rock permeability properties (e.g., where A is a positive integer) for each facies juxtaposition type of the fault plane based on each facies juxtaposition type’s respective fault rock permeability range to generate A scenarios of practical permeability properties (also referred to herein as “A candidate fault plane permeability scenarios”) along the fault plane for fault seal analysis. Fault seal properties, such as fault transmissibility, fault sealing capacity, etc., may be generated for eachcandidate fault plane permeability scenario to better understand the range of fault seal properties associated with the fault plane for improved fault seal analysis. In certain embodiments, visualizations (e.g., illustrations, graphs, scatter plots, etc.) of fault seal property(ies) determined for one or more candidate fault plane permeability scenarios are generated for display to allow for more effective communication of the fault seal properties generated for each practical scenario. The visualizations may be used to aid in making informed decisions for hydrocarbon drilling, exploration, and / or development in carbonate reservoirs.

[0026] Notably, using a stochastic approach to predict fault rock permeability properties has the beneficial technical effect of improving capacity to handle the uncertainty associated with fault rock properties in carbonate reservoirs. For example, using a stochastic approach to generate multiple candidate fault plane permeability scenarios helps to illustrate the likely range of fault sealing capacity for a subsurface fault plane. Instead of analyzing a single estimate of a fault rock permeability for each facies juxtaposition type of a fault plane when predicting a behavior of the fault plane, many different estimates of feasible fault rock permeability properties may be analyzed. As such, fault seal analysis may be more accurate and provide a more complete view of possible fault behavior in reservoirs exhibiting complex geology and heterogeneity. Further, a range of fault seal properties determined for each of the candidate fault plane permeability scenarios may be used to create ranges of trap filling scenarios for hydrocarbon exploration applications and / or likely ranges of production parameters for field development planning purposes, among others.

[0027] Further, the fault seal analysis workflow described herein provides a method that may be used to evaluate fault sealing capacity and permeability in a wide range of reservoirs, including those with minimal clay content. In particular, as described above, a technical problem of existing fault seal analyses is their inability to estimate fault seal properties of faults in a faulted reservoir where fault rock clay content percentage is low (e.g., 0-15% clay content). The techniques described herein overcome this technical problem and improve upon the state of the art by enabling this analysis in such reservoirs to predict fault behavior and to reduce uncertainty and risk in faulted reservoir exploitation. This new workflow beneficially improves the accuracy, reliability, and meaningfulness of fault seal properties estimated for faults in carbonate-dominated host rocks.Example System for Fault Seal Analysis

[0028] FIGS. 1A-1B depict an example system 100 for predicting fault seal behavior of fault(s) in faulted carbonate reservoirs. Though techniques herein are described with respect to carbonate reservoirs, the techniques may be similarly applied to predict fault seal behavior of fault(s) in other types of faulted reservoirs. For example, in some cases, the techniques described herein may be used to predict fault seal behavior of fault(s) in siliciclastic reservoirs, as an alternative to conventional fault seal analysis methods described herein.

[0029] As shown in FIGS. 1A-1B, predicting fault seal behavior of fault(s) in faulted carbonate reservoirs includes fault plane identification 102, facies juxtaposition types identification 108, permeability range estimation 116 (e.g., per facies juxtaposition type), candidate fault plane permeability scenarios generation 118, and fault seal property(ies) determination and display 126.

[0030] Fault plane identification 102 includes identifying fault plane(s) (e.g., fault plane 106) in a subsurface model 104 for fault seal analysis. The subsurface model 104 may represent one or more petrophysical properties of a reservoir structure. For example, subsurface model 104 may be appropriately populated with facies, porosity, and / or permeability grid properties. In certain embodiments, the subsurface model 104 is a model obtained for fault plane identification 102. Alternatively, in certain embodiments (not shown in FIGS. 1A-1B), system 100 additionally performs subsurface model generation using, for example, industry standard subsurface geological modelling software. For example, in some cases, subsurface model 104 is generated using Petrel® software made available by Schlumberger® Ltd. of Houston, Texas. Specifically, Petrel® is software that may be used to analyze subsurface data from exploration to production, thereby enabling the creation of a subsurface model of a reservoir.

[0031] An example subsurface model 104 used for fault plane identification 102 is depicted in FIG. 1C. The example subsurface model 104 may be based on an oil and gas field located in Norway. As shown in a first depiction 122 of subsurface model 104 in FIG. 1C, the subsurface model 104 is populated with (1) grain-dominated facies (e.g., assumed to be non-reservoir-sealing lithology) and (2) micrite-dominated facies (e.g., assumed to be reservoir-sealing lithology) based on Malta stratigraphy for testing. Facies are particularly populated along the fault planes in subsurface model 104 for fault seal analysis. Although the subsurface model 104 shown in FIG.1C is based on an oil and gas field located in Norway and includes facies based on Malta geology, other examples of the subsurface model 104 may be based on carbonate-hosted reservoirs in other locations and having different facies.

[0032] Further, as shown in a second depiction 124 of subsurface model 104 in FIG. 1C, key petrophysical properties, such as permeability and porosity (e.g., VClay, or the volume fraction of clay minerals, is not used to estimate fault clay content in this workflow, which is typically used in siliciclastic reservoirs, as described herein), are also populated. The petrophysical properties may be based on publicly-available data. For example, (1) a normal distribution of porosity values with a mean of 0.25 and a standard deviation of 0.0375 and (2) a log normal distribution of permeability values with a mean of 100 millidarcies (mD) and a standard deviation of 40 mD are populated in subsurface model 104 for lower coralline limestone (e.g., an example grain- dominated facies). Further, (1) a normal distribution of porosity values with a mean of 0.25 and a standard deviation of 0.0375 and (2) a log normal distribution of permeability values with a mean of 2 mD and a standard deviation of 1 mD are populated in subsurface model 104 for globigerina limestone (e.g., an example micrite-dominated facies).

[0033] Fault plane identification 102 involves identifying one or more fault planes 106 in subsurface model 104. For ease of explanation, only one fault plane 106 is identified in subsurface model 104 for fault seal analysis in FIGS. 1A-1B; however, in other embodiments, multiple fault planes 106 may be identified and analyzed. As described above, an identified fault plane 106 may be a break or planar surface in subsurface model 104 across which there is observable rock displacement.

[0034] Facies juxtaposition types identification 108 includes identifying a plurality of facies juxtaposition types for fault plane 106. Each facies juxtaposition type may identify different facie pairs in contact along the at least one fault plane. For example, as shown in FIG. 1A, due to displacement of rock at fault plane 106, a first facies 110 on a left side of fault plane 106 may be in contact with first facies 110 on a right side of fault plane 106, which may represent a first facies pair or a first facies juxtaposition type (e.g., a self / similar juxtaposition). A second facies 112 on a left side of fault plane 106 may be in contact with second facies 112 on a right side of fault plane 106, which may represent a second facies pair or a second facies juxtaposition type (e.g., a self / similar juxtaposition). Further, first facies 110 on a left side of fault plane 106 may be incontact with second facies 112 on a right side of fault plane 106, and vice versa, which may represent third and fourth facies pairs or third and fourth facies juxtaposition types identified for fault plane 106.

[0035] The example illustrated in FIGS. 1A-1B provides a simple depiction of different facies juxtaposition types that may be identified along fault plane 106; however, when using system 100 to perform the fault seal analysis described herein, many facies juxtaposition types may be identified along fault plane 106, as shown in FIG. ID.

[0036] In particular, FIG. ID illustrates two types of facies juxtaposition types that may be identified along fault plane 106: (1) self / similar facies juxtaposition types having homogeneous microstructures and permeability and (2) facies juxtaposition types with different facies having heterogeneous microstructures and permeability.

[0037] As shown, example self / similar facies juxtaposition types along fault plane 106(1), shown at 130, may include fractured cataclasite (e.g., high permeability) shown at 132, cataclasite with minor overprinting (e.g., low permeability) shown at 134, cataclasite (e.g., low permeability) shown at 136, and moldic porosity created through the dissolution of a preexisting constituent of a rock (e.g., high porosity and low permeability) and shown at 138.

[0038] Further, example facies juxtaposition types with different facies along fault plane 106(2), shown at 140, may include cemented rock with later fracturing (e.g., high permeability) shown at 142, cohesive breccia (e.g., low permeability) shown at 144, incohesive breccia (e.g., high permeability) shown at 146, and cataclasite (e.g., low permeability) shown at 148. In certain embodiments, late-stage fracturing and / or dissolution may overprint original textures, acting to increase permeability heterogeneity along fault plane 106(2).

[0039] Permeability range estimation 116, in FIG. IB, includes estimating a fault rock permeability range for each facies juxtaposition type identified at facies juxtaposition types identification 108 for fault plane 106. For example, in a model having four facies types, ten facies juxtaposition types may be possible and identified along fault plane 106. In particular, each facies against itself along fault plane 106 may create four facies juxtaposition types. Further, the first facies against the second, third, and fourth facies may create another three facies juxtaposition types, the second facies against the third and fourth facies may create another two faciesjuxtaposition types, and the third facies against the fourth facies may create one more facies juxtaposition type (e.g., 4 + 3 + 2 + 1 = 10 facies juxtaposition types). Permeability range estimation 116 may include estimating a first fault rock permeability range of plausible permeability values for the first facies juxtaposition type, a second fault rock permeability range of plausible permeability values for the second facies juxtaposition type, a third fault rock permeability range of plausible permeability values for the third facies juxtaposition type, and so on until ten fault rock permeability ranges are estimated for the ten possible facies juxtaposition types.

[0040] Although the example describes a model having four facies types and thus, ten possible facies juxtaposition types, in some other examples, more or less facies types resulting in more or less facies juxtaposition types may exist. Permeability range estimation 116 may include estimating a fault rock permeability range of plausible permeability values for each facies juxtaposition type.

[0041] Different facies juxtaposition types may have different properties and / or property variability. Thus, different fault rock permeability ranges may be estimated for each facies juxtaposition type. In certain embodiments, fault rock permeability ranges estimated for the facies juxtaposition type are further based on host rock porosity and / or host rock permeability. For example, rock type and properties, such as porosity and / or permeability, of the rocks against the fault plane, may influence the permeability range estimated for each facies juxtaposition type. Further, burial and / or diagenetic histories of rocks juxtaposed across the fault plane and / or variability across the fault plane may influence the permeability range estimated for each facies juxtaposition type. For example, where a facies is juxtaposed against itself along the fault plane, the estimated permeability range may be smaller than ranges for other facies juxtaposition types where different facies are juxtaposed.

[0042] Candidate fault plane permeability scenarios generation 118, in FIG. IB, includes generating candidate fault plane permeability scenarios with various fault plane permeability properties assigned to different facies juxtaposition types. For example, for each candidate fault plane permeability scenario, a candidate fault plane permeability property may be assigned to each facies juxtaposition type identified along the fault plane 106. A candidate fault plane permeability property assigned to a facies juxtaposition type may have a value within the fault rock permeabilityrange estimated for the particular facies juxtaposition type (e.g., estimated at permeability range estimation 116).

[0043] In certain embodiments, a simulation is used to assign the fault plane permeability properties to the facies juxtaposition types for each candidate fault plane permeability scenario. In certain embodiments, the simulation is a Monte Carlo simulation. A Monte Carlo simulation is a mathematical technique that may be used to simulate a range of possible fault plane permeability properties for each facies juxtaposition type along fault plane 106 for the multiple candidate fault plane permeability scenarios. Fault plane permeability property predictions generated for each facies juxtaposition type for the multiple candidate fault plane permeability scenarios may be based on the estimated range of fault rock permeability determined for the particular facies juxtaposition type during permeability range estimation 116. In certain embodiments, a Python® (or other scripting language) script may be used to create X candidate fault permeability scenarios (e.g., such as X= 1,000 candidate fault plane permeability scenarios) where each facies juxtaposition type along fault plane 106 is assigned a fault plane permeability property based on the Monte Carlo simulation.

[0044] FIG. IE depicts example fault plane permeability properties assigned to facies juxtaposition types along fault plane 106 for different candidate fault plane permeability scenarios. As shown, three facies juxtaposition types are identified along fault plane 106 including (1) lower coralline limestone (grain-dominated) self-juxtapositions, (2) globigerina limestone (micrite- dominated) self-juxtapositions, and (3) grain-dominated and micrite-dominated limestones juxtapositions. A fault rock permeability range determined for lower coralline limestone (grain- dominated) self-juxtapositions (e.g., determined at permeability range estimation 116) includes values between, and including, 0.01 mD and 1 mD. A fault rock permeability range determined for globigerina limestone (micrite-dominated) self-juxtapositions (e.g., determined at permeability range estimation 116) includes values between, and including, 0.001 mD and 0.1 mD. Further, a fault rock permeability range determined for grain-dominated and micrite-dominated limestones juxtapositions (e.g., determined at permeability range estimation 116) includes values between, and including, 0.00001 mD and 1 mD.

[0045] To generate a first candidate fault plane permeability scenario 120(1), a Monte Carlo (or other type of) simulation may be used to (1) assign lower coralline limestone (grain-dominated)self-juxtapositions along fault plane 106 a candidate fault plane permeability property from the fault rock permeability range of 0.01 - 1 mD, (2) assign globigerina limestone (micrite-dominated) self-juxtapositions along fault plane 106 a candidate fault plane permeability property from the fault rock permeability range of 0.001 - 0.1 mD, and (3) assign grain-dominated and micrite- dominated limestones juxtapositions along fault plane 106 a candidate fault plane permeability property from the fault rock permeability range of 0.00001 - 1 mD. In this example, for the first candidate fault plane permeability scenario 120(1), a fault plane permeability property equal to 1 mD is assigned to lower coralline limestone (grain-dominated) self-juxtapositions, a fault plane permeability property equal to 0.1 mD is assigned to globigerina limestone (micrite-dominated) self-juxtapositions, and a fault plane permeability property equal to 1 mD is assigned to grain- dominated and micrite-dominated limestones juxtapositions.

[0046] Further simulation(s) may be used to generate other candidate fault plane permeability scenarios up to X candidate fault plane permeability scenarios. For example, in certain embodiments, 1,000 candidate fault plane permeability scenarios may be generated. In the example depicted in FIG. IE, for the Xth candidate fault plane permeability scenario 120(20, a fault plane permeability property equal to 0.01 mD is assigned to lower coralline limestone (grain-dominated) self-juxtapositions, a fault plane permeability property equal to 0.001 mD is assigned to globigerina limestone (micrite-dominated) self-juxtapositions, and a fault plane permeability property equal to 0.00001 mD is assigned to grain-dominated and micrite-dominated limestones juxtapositions.

[0047] Fault seal property(ies) determination and display 126, in FIG. IB, includes determining fault seal property(ies) of fault plane 106 for one or more of the candidate fault plane permeability scenarios 12O(1)-12O(20. For example, fault seal property(ies) of fault plane 106 may be determined using the plurality of candidate fault plane permeability properties assigned to the plurality of facies juxtaposition types (e.g., assigned at candidate fault plane permeability scenarios generation 118) for each respective candidate fault plane permeability scenario. As an illustrative example, the fault plane permeability property equal to 1 mD and assigned to lower coralline limestone (grain-dominated) self-juxtapositions, the fault plane permeability property equal to 0.1 mD and assigned to globigerina limestone (micrite-dominated) self-juxtapositions, and the fault plane permeability property equal to 1 mD and assigned to grain-dominated and micrite-dominatedlimestones juxtapositions for first candidate fault plane permeability scenario 120(1) in FIG. IE may be used to determine fault seal property(ies) of fault plane 106 in first candidate fault plane permeability scenario 120(1).

[0048] Example fault seal properties that may be determined at fault seal property(ies) determination and display 126 may include a fault transmissibility multiplier (TM), dynamic measures of model connectivity, average fault transmissibility, effective cross-fault transmissibility (ECFT), fault sealing capacity, and / or free water level(s).

[0049] Fault transmissibility reflects the ability of rock along a fault plane to allow fluid to enter and flow from one side of the fault plane to another. A fault TM is generally used for flow simulation to represent such fault transmissibility per fault plane. For example, fault planes may be commonly represented in flow simulation by a multiplier applied to an interface between selected facies along the fault plane. Dynamic measures of model connectivity are measurements relating to subsurface fluid flow behavior. Dynamic measures of model connectivity may be derived from the flow simulation, for example connate fluid production, connected pore volume, and / or break through time. Average fault transmissibility represents the average ability of rock along the fault plane to allow fluid to enter and flow from one side of the fault plane to another. Average fault transmissibility may be based on fault properties as opposed to the properties of adjacent grid cells. ECFT is a measure of transmissibility across the grid cells adjacent to a fault plane and across the fault plane based on the grid and fault properties. Fault sealing capacity associated with a fault plane represents a hydrocarbon column height supported by the fault plane. Lastly, a free water level associated with a fault plane is defined as the horizontal plane (e.g., depth) where the oil pressure equalizes the water pressure, i.e., where the capillary pressure is zero. The free water level may approximate the hydrocarbon-water contact.

[0050] In certain embodiments, fault seal property(ies) determination and display 126 further includes generating the fault seal property(ies) determined for the candidate fault plane permeability scenario(s) for display on a computing device. Additional details regarding the generation and display of different fault seal property(ies) are provided herein with respect to FIGS. 2-4CExample Workflow Output Depicting Predicted Fault Seal Properties

[0051] As described above, in certain embodiments, a fault plane seal property determined for each candidate fault plane permeability scenarios 120 includes a fault TM. For example, one fault TM may be determined per candidate fault plane permeability scenario 120 using the candidate fault plane permeability properties assigned to the facies juxtaposition types along fault plane 106 (e g., assigned at candidate fault plane permeability scenarios generation 118 in FIGS. 1A-1B) for the respective scenario. The fault TM determined for each candidate fault plane permeability scenario 120 may be calculated with stochastically varying fault thickness, for example, based on a displacement to thickness ratio between 10:1 and 10,000: 1. The fault TM determined for each candidate fault plane permeability scenario 120 may be variable across fault plane 106.

[0052] In certain embodiments, the fault TM determined for each candidate fault plane permeability scenario 120 is used to further determine dynamic measures of model connectivity for each respective candidate fault plane permeability scenario 120. For example, fault TMs may be run through a streamline simulator (e.g., such as using Schlumberger’s Petrel Geoscreening plug-in) to generate dynamic measures of model connectivity (connate fluid production, connected pore volume and break through time) for each candidate fault plane permeability scenario 120.

[0053] In certain embodiments, the dynamic measures of model connectivity determined for each candidate fault plane permeability scenario 120 may be generated for display to a user. FIG. 2 is an example scatter plot 200 generated for display based on dynamic measures of model connectivity associated with multiple candidate fault plane permeability scenarios 120. As shown in FIG. 2, an x-axis of scatter plot 200 represents connate fluid production (m3) and a y-axis of scatter plot 200 represent connected pore volume (m3). Each data point in scatter plot represents dynamic measures of connectivity determined for a single candidate fault plane permeability scenario 120. For this example, dynamic measures of connectivity were determined for 100 candidate fault plane permeability scenarios; thus, scatter plot 200 includes 100 data points, each representing a different candidate fault plane permeability scenario 120. Scatter plot 200 provides a visual representation of the possible range of dynamic measures of connectivity that may be plausible for the fault plane 106 based on stochastically generated fault plane permeability properties. With this visualization, a user may be able to identify one or more candidate fault plane permeability scenarios 120. For example, a user may be able to identify a candidate fault planepermeability scenario 120 that represents a bottom percentage of the total candidate fault plane permeability scenarios 120 (e.g., such as tenth candidate fault plane permeability scenario 120(10) (e.g., bottom l / 3rd)). As another example, a user may be able to identify a candidate fault plane permeability scenario 120 that represents a middle percentage of the total candidate fault plane permeability scenarios 120 (e g., such as fiftieth candidate fault plane permeability scenario 120(50) (e.g., middle l / 3rd)). As another example, a user may be able to identify a candidate fault plane permeability scenario 120 that represents a top percentage of the total candidate fault plane permeability scenarios 120 (e.g., such as ninetieth candidate fault plane permeability scenario 120(90) (e.g., top l / 3rd)).

[0054] In certain embodiments, a fault plane seal property determined for each candidate fault plane permeability scenario 120 includes an average fault transmissibility for fault plane 106. For example, an average fault transmissibility of fault plane 106 may be determined per candidate fault plane permeability scenario 120 using the fault TM calculated for the respective scenario 120. In certain embodiments, the average fault transmissibility of fault plane 106 (and / or one or more other fault planes) for one or more candidate fault plane permeability scenarios 120 may be generated for display to a user.

[0055] FIG. 3 is an example visualization 300 generated for display to depict the predicted average transmissibility of multiple fault planes for a single candidate fault plane permeability scenario 120, such as the 50thcandidate fault plane permeability scenario 120(50). Although visualization 300 is generated for fiftieth candidate fault plane permeability scenario 120(50), in other examples, similar visualizations may be generated for other candidate fault plane permeability scenarios, such as tenth candidate fault plane permeability scenario 120(10), ninetieth candidate fault plane permeability scenario 120(90), etc.

[0056] As shown in FIG. 3, pie charts may be generated and placed over each fault plane in visualization 300. The size of each pie chart may represent the average transmissibility calculated for each fault plane based on permeability properties assigned to facies juxtaposition types in the 50th candidate fault plane permeability scenario 120(50). Larger pie charts in visualization 300 may represent more transmissive fault planes than those faults planes having smaller pie charts. The slices (also referred to as “segments”) of each pie chart may be sized according to average ECFT values for the fault planes in the tenth candidate fault plane permeability scenario 120(10),fiftieth candidate fault plane permeability scenario 120(50), and ninetieth candidate fault plane permeability scenario 120(90) (e.g., each slice corresponds to one of the three candidate fault plane permeability scenarios 120(10), 120(50), 120(90)). As such, the pie charts may provide an indication of the relative transmissibility between candidate fault plane permeability scenarios 120(10), 120(50), 120(90). For example, if the segments are of similar size then there may not be much difference between the scenarios, and if there is a large difference in segment size then there may be larger uncertainty.

[0057] Although pie charts in visualization 300 are generated for candidate fault plane permeability scenarios 120(10), 120(50), 120(90), in other example visualizations, similar pie charts may be generated for other candidate fault plane permeability scenarios.

[0058] In certain embodiments, fault plane seal properties determined for each candidate fault plane permeability scenario 120 include fault sealing capacity and / or predicted free water level elevation. For example, stochastic fault permeability properties assigned to facies juxtaposition types for fault plane 106 in a candidate fault plane permeability scenario 120 may be converted to seal capacity and / or predicted free water level elevation according to the following steps. In a first step, each fault permeability property may be converted to an air threshold pressure in Hg (e.g., unit of atmospheric pressure used in the United States) using a known relationship, such as:Pf= 31.838-0 3848where Pf represents the capillary threshold pressure and / ^represents the fault permeability.

[0059] In a second step, each air threshold pressure may be converted to an in situ threshold for a same hydrocarbon-brine interfacial tension and contact angle. For example, each air threshold pressure may be converted to in situ threshold assuming that hydrocarbon-brine interfacial tension is 25 dynecm-1and the contact angle is 0°. In a third step, each in situ threshold is used to calculate a seal capacity for the respective facies juxtaposition type associated with the in situ threshold. Each seal capacity for each facies juxtaposition type may be calculated based on a same hydrocarbon density (e.g., such as 800 kgm3) and a same brine density (e.g., such as 1,115 kgm3). Free water level elevation for each face of fault plane 106 corresponding to a different facies juxtaposition type along fault plane 106 is then determined by subtracting the seal capacitydetermined for the facies juxtaposition type from an elevation of the respective face of fault plane 106.

[0060] In certain embodiments, fault sealing capacities and / or free water levels predicted for candidate fault plane permeability scenario 120 may be generated for display to a user. For example, FIG. 4A is an example visualization 400a (e.g., a part of a graphical user interface) depicting predicted fault sealing capacity of a fault plane in an Ath candidate fault plane permeability scenario 120(A). Visualization 400a may be an example visualization generated for display to a user. In FIG. 4A, a fault sealing capacity for each fault face of the fault plane 106 is illustrated. The fault sealing capacity of each fault face may be based on a facies juxtaposition type of each fault face.

[0061] FIG. 4B is an example visualization 400b (e.g., a part of a graphical user interface) depicting predicted free water levels of a fault plane in an Ath candidate fault plane permeability scenario 120(A). Visualization 400b may be an example visualization generated for display to a user. Instead of displaying the free water level predicted for each fault face of fault plane 106, visualization 400b depicts predicted free water levels for only high risk locations (e.g., high risk fault faces) along fault plane 106 in the Ath candidate fault plane permeability scenario 120(A).

[0062] For example, high-risk locations along fault plane 106 may include fault faces (1) associated with a specific facies juxtaposition type and (2) having a fault rock discontinuity risk greater than a threshold fault rock discontinuity risk. For example, high-risk locations along fault plane 106 may correspond to fault faces having reservoir-to-reservoir juxtapositions and a fault rock discontinuity risk greater than 20%.

[0063] FIG. 4C is an example visualization 400c (e.g., a part of a graphical user interface) depicting predicted fault rock discontinuity risk for fault plane 106 in Ath candidate fault plane permeability scenario 120(A). For visualization 400c, the risk of fault rock being discontinuous is assumed to be 100% at zero throw and decreases linearly to 0% at 50 meters (m) throw. This fault rock discontinuity risk property may be determined for each fault face of the fault plane based on the fault throw and, in some cases, further used to filter the sealing capacity results (e.g., such as sealing capacity results displayed in FIG. 4B).Example Operations for Fault Seal Analysis

[0064] FIG. 5 depicts an example method 500 for fault seal analysis. Method 500 may be performed by one or more processor(s) of a computing device, such as processor(s) 602 of processing system 600 described below with respect FIG. 6.

[0065] Method 500 begins, at block 502, with identifying at least one fault plane in a subsurface model representing one or more petrophysical properties of a reservoir structure.

[0066] Method 500 proceeds, at block 504, with determining a plurality of facies juxtaposition types for the at least one fault plane, each facies juxtaposition type of the plurality of facies juxtaposition types identifying different facies pairs in contact along the at least one fault plane.

[0067] Method 500 proceeds, at block 506, with estimating a fault rock permeability range for each facies juxtaposition type of the plurality of facies juxtaposition types.

[0068] Method 500 proceeds, at block 508, with generating a plurality of candidate fault plane permeability scenarios, wherein for each candidate fault plane permeability scenario, a candidate fault plane permeability property is assigned to each facies juxtaposition type of the plurality of facies juxtaposition types using a simulation and the fault rock permeability range estimated for each facies juxtaposition type.

[0069] Method 500 proceeds, at block 510, with for each candidate fault plane permeability scenario of one or more candidate fault plane permeability scenarios of the plurality of candidate fault plane permeability scenarios, determining one or more fault seal properties for the at least one fault plane using the plurality of candidate fault plane permeability properties assigned to the plurality of facies juxtaposition types for the respective candidate fault plane permeability scenario.

[0070] Method 500 proceeds, at block 512, with generating the one or more fault seal properties for the one or more candidate fault plane permeability scenarios for display on a computing device.

[0071] In certain embodiments, the simulation is a Monte Carlo simulation.

[0072] In certain embodiments, determining the one or more fault seal properties for the respective candidate fault plane permeability scenario includes (1) calculating a fault TM for theat least one fault plane using the plurality of candidate fault plane permeability properties assigned to the plurality of facies juxtaposition types for the respective candidate fault plane permeability scenario, wherein the fault TM is variable across the at least one fault plane, and (2) generating dynamic measures of model connectivity using the fault TM.

[0073] In certain embodiments, generating the one or more fault seal properties for display on the computing device includes generating a scatter plot based on the dynamic measures of model connectivity generated for each candidate fault plane permeability scenario of the one or more candidate fault plane permeability scenarios.

[0074] In certain embodiments, determining the one or more fault seal properties for the respective candidate fault plane permeability scenario includes calculating an average fault transmissibility for the fault plane using the fault TM calculated for the respective candidate fault plane permeability scenario.

[0075] In certain embodiments, generating the one or more fault seal properties for display on the computing device includes generating a pie chart for each of the one or more candidate fault plane permeability scenarios representing the average fault transmissibility calculated for the respective candidate fault plane permeability scenario.

[0076] In certain embodiments, determining the one or more fault seal properties for the respective candidate fault plane permeability scenario includes, for each facies juxtaposition type: determining a fault sealing capacity using the candidate fault plane permeability property assigned to the respective facies juxtaposition type for the respective candidate fault plane permeability scenario and based on a hydrocarbon density and a brine density.

[0077] In certain embodiments, determining the one or more fault seal properties for the respective candidate fault plane permeability scenario further includes, for each facies juxtaposition type, determining a free water level based on the fault sealing capacity determined for the respective facies juxtaposition type for the respective candidate fault plane permeability scenario.

[0078] In certain embodiments, generating the one or more fault seal properties for display on the computing device includes, for each candidate fault plane permeability scenario of the one or more candidate fault plane permeability scenarios, generating for display the free water leveldetermined for one or more facies juxtaposition types for the respective candidate fault plane permeability scenario based on a risk level associated with each of the one or more facies juxtaposition types being above a threshold risk level.

[0079] In certain embodiments, the risk level associated with each facies juxtaposition type is based on a threshold fault rock discontinuity risk.

[0080] In certain embodiments, the risk level associated with each facies juxtaposition type is based a type of facies juxtaposition corresponding to each facies juxtaposition type.

[0081] In certain embodiments, the one or more fault seal properties for the at least one fault plane include at least one of: a fault TM; dynamic measures of model connectivity; an average fault transmissibility; a fault sealing capacity; or a free water level.

[0082] In certain embodiments, the one or more petrophysical properties of the reservoir structure include at least one of porosity or permeability.

[0083] Note that FIG. 5 is just one example of a method, and other methods including fewer, additional, or alternative steps are possible consistent with this disclosure.Example Processing System for Fault Seal Analysis

[0084] FIG. 6 depicts an example processing system 600 configured to perform various aspects described herein, including, for example, method 500 as described above with respect to FIG. 5

[0085] Processing system 600 is generally an example of an electronic device configured to execute computer-executable instructions, such as those derived from compiled computer code, including without limitation personal computers, tablet computers, servers, smart phones, smart devices, wearable devices, augmented and / or virtual reality devices, and others.

[0086] In the depicted example, processing system 600 includes one or more processors 602, one or more input / output devices 604, one or more display devices 606, one or more network interfaces 608 through which processing system 600 is connected to one or more networks (e.g., a local network, an intranet, the Internet, or any other group of processing systems communicatively connected to each other), and computer-readable medium 670. In the depicted example, the aforementioned components are coupled by a bus 610, which may generally be configured for dataexchange amongst the components. Bus 610 may be representative of multiple buses, while only one is depicted for simplicity.

[0087] Processor(s) 602 are generally configured to retrieve and execute instructions stored in one or more memories, including local memories like computer-readable medium 670, as well as remote memories and data stores. Similarly, processor(s) 602 are configured to store application data residing in local memories like the computer-readable medium 670, as well as remote memories and data stores. More generally, bus 610 is configured to transmit programming instructions and application data among the processor(s) 602, display device(s) 606, network interface(s) 608, and / or computer-readable medium 670. In certain embodiments, processor(s) 602 are representative of one or more central processing units (CPUs), graphics processing unit (GPUs), tensor processing unit (TPUs), accelerators, and other processing devices.

[0088] Input / output device(s) 604 may include any device, mechanism, system, interactive display, and / or various other hardware and software components for communicating information between processing system 600 and a user of processing system 600. For example, input / output device(s) 604 may include input hardware, such as a keyboard, touch screen, button, microphone, speaker, and / or other device for receiving inputs from the user and sending outputs to the user.

[0089] Display device(s) 606 may generally include any sort of device configured to display data, information, graphics, user interface elements, and the like to a user. For example, display device(s) 606 may include internal and external displays such as an internal display of a tablet computer or an external display for a server computer or a projector. Display device(s) 606 may further include displays for devices, such as augmented, virtual, and / or extended reality devices. In various embodiments, display device(s) 606 may be configured to display a graphical user interface.

[0090] Network interface(s) 608 provide processing system 600 with access to external networks and thereby to external processing systems. Network interface(s) 608 can generally be any hardware and / or software capable of transmitting and / or receiving data via a wired or wireless network connection. Accordingly, network interface(s) 608 can include a communication transceiver for sending and / or receiving any wired and / or wireless communication.

[0091] Computer-readable medium 670 may be a volatile memory, such as a random access memory (RAM), or a nonvolatile memory, such as nonvolatile random access memory (NVRAM), or the like. In this example, computer-readable medium 670 includes fault plane identification component 620, facies juxtaposition types identification component 622, permeability range estimation component 624, candidate fault plane scenarios generation component 626, fault seal property(ies) determination component 628, fault seal property(ies) display component 630, a subsurface model 632, facies juxtaposition types 634, fault rock permeability ranges 636, candidate fault permeability properties 637, fault seal properties 638, fault TMs 640, dynamic measures of model connectivity 642, average fault transmissibilities 644, fault sealing capacities 646, free water levels 648, identifying logic 650, determining logic 652, estimating logic 654, generating logic 656, performing logic 658, and calculating logic 660.

[0092] In certain embodiments, identifying logic 650 includes logic for identifying at least one fault plane in a subsurface model representing one or more petrophysical properties of a reservoir structure.

[0093] In certain embodiments, determining logic 652 includes logic for determining a plurality of facies juxtaposition types for the at least one fault plane. In certain embodiments, determining logic 652 includes logic for determining one or more fault seal properties for at least one fault plane using a plurality of candidate fault plane permeability properties assigned to a plurality of facies juxtaposition types for a candidate fault plane permeability scenario. In certain embodiments, determining logic 652 includes logic for determining a fault sealing capacity using the candidate fault plane permeability property assigned to the respective facies juxtaposition type for the respective candidate fault plane permeability scenario and based on a hydrocarbon density and a brine density. In certain embodiments, determining logic 652 includes logic for determining a free water level based on the fault sealing capacity determined for the respective facies juxtaposition type for the respective candidate fault plane permeability scenario.

[0094] In certain embodiments, estimating logic 654 includes logic for estimating a fault rock permeability range for each facies juxtaposition type of the plurality of facies juxtaposition types.

[0095] In certain embodiments, generating logic 656 includes logic for generating a plurality of candidate fault plane permeability scenarios. In certain embodiments, generating logic 656 includes logic for generating the one or more fault seal properties for the one or more candidatefault plane permeability scenarios for display on a computing device. In certain embodiments, generating logic 656 includes logic for generating a scatter plot based on the dynamic measures of model connectivity generated for each candidate fault plane permeability scenario of the one or more candidate fault plane permeability scenarios. In certain embodiments, generating logic 656 includes logic for generating a pie chart for each of the one or more candidate fault plane permeability scenarios representing the average fault transmissibility calculated for the respective candidate fault plane permeability scenario. In certain embodiments, generating logic 656 includes logic for generating dynamic measures of model connectivity using the fault TM In certain embodiments, generating logic 656 includes logic for generating for display the free water level determined for one or more facies juxtaposition types for the respective candidate fault plane permeability scenario based on a risk level associated with each of the one or more facies juxtaposition types being above a threshold risk level.

[0096] In certain embodiments, performing logic 658 includes logic for performing a fault seal analysis.

[0097] In certain embodiments, calculating logic 660 includes logic for calculating a fault TM for the at least one fault plane using the plurality of candidate fault plane permeability properties assigned to the plurality of facies juxtaposition types for the respective candidate fault plane permeability scenario, wherein the fault TM is variable across the at least one fault plane. In certain embodiments, calculating logic 660 includes logic for calculating an average fault transmissibility for the fault plane using the fault TM calculated for the respective candidate fault plane permeability scenario.

[0098] Note that FIG. 6 is just one example of a processing system consistent with aspects described herein, and other processing systems having additional, alternative, or fewer components are possible consistent with this disclosure.Example Clauses

[0099] Implementation examples are described in the following numbered clauses:

[0100] Clause 1 : A method of fault seal analysis, comprising: identifying at least one fault plane in a subsurface model representing one or more petrophysical properties of a reservoir structure; determining a plurality of facies juxtaposition types for the at least one fault plane, eachfacies juxtaposition type of the plurality of facies juxtaposition types identifying different facies pairs in contact along the at least one fault plane; estimating a fault rock permeability range for each facies juxtaposition type of the plurality of facies juxtaposition types; generating a plurality of candidate fault plane permeability scenarios, wherein for each candidate fault plane permeability scenario, a candidate fault plane permeability property is assigned to each facies juxtaposition type of the plurality of facies juxtaposition types using a simulation and the fault rock permeability range estimated for each facies juxtaposition type; for each candidate fault plane permeability scenario of one or more candidate fault plane permeability scenarios of the plurality of candidate fault plane permeability scenarios, determining one or more fault seal properties for the at least one fault plane using the plurality of candidate fault plane permeability properties assigned to the plurality of facies juxtaposition types for the respective candidate fault plane permeability scenario; and generating the one or more fault seal properties for the one or more candidate fault plane permeability scenarios for display on a computing device.

[0101] Clause 2: The method of Clause 1, wherein the simulation comprises a Monte Carlo simulation.

[0102] Clause 3 : The method of any one of Clauses 1-2, wherein determining the one or more fault seal properties for the respective candidate fault plane permeability scenario comprises: calculating a fault transmissibility multiplier (TM) for the at least one fault plane using the plurality of candidate fault plane permeability properties assigned to the plurality of facies juxtaposition types for the respective candidate fault plane permeability scenario, wherein the fault TM is variable across the at least one fault plane; and generating dynamic measures of model connectivity using the fault TM.

[0103] Clause 4: The method of Clause 3, wherein generating the one or more fault seal properties for display on the computing device comprises generating a scatter plot based on the dynamic measures of model connectivity generated for each candidate fault plane permeability scenario of the one or more candidate fault plane permeability scenarios.

[0104] Clause 5: The method of any one of Clauses 3-4, wherein determining the one or more fault seal properties for the respective candidate fault plane permeability scenario comprises calculating an average fault transmissibility for the fault plane using the fault TM calculated for the respective candidate fault plane permeability scenario.

[0105] Clause 6: The method of Clause 5, wherein generating the one or more fault seal properties for display on the computing device comprises generating a pie chart for each of the one or more candidate fault plane permeability scenarios representing the average fault transmissibility calculated for the respective candidate fault plane permeability scenario.

[0106] Clause 7: The method of any one of Clauses 1-6, wherein determining the one or more fault seal properties for the respective candidate fault plane permeability scenario comprises: for each facies juxtaposition type: determining a fault sealing capacity using the candidate fault plane permeability property assigned to the respective facies juxtaposition type for the respective candidate fault plane permeability scenario and based on a hydrocarbon density and a brine density.

[0107] Clause 8: The method of Clause 7, wherein determining the one or more fault seal properties for the respective candidate fault plane permeability scenario further comprises: for each facies juxtaposition type: determining a free water level based on the fault sealing capacity determined for the respective facies juxtaposition type for the respective candidate fault plane permeability scenario.

[0108] Clause 9: The method of Clause 8, wherein generating the one or more fault seal properties for display on the computing device comprises: for each candidate fault plane permeability scenario of the one or more candidate fault plane permeability scenarios: generating for display the free water level determined for one or more facies juxtaposition types for the respective candidate fault plane permeability scenario based on a risk level associated with each of the one or more facies juxtaposition types being above a threshold risk level.

[0109] Clause 10: The method of Clause 9, wherein the risk level associated with each facies juxtaposition type is based on a threshold fault rock discontinuity risk.

[0110] Clause 11 : The method of Clause 9, wherein the risk level associated with each facies juxtaposition type is based a type of facies juxtaposition corresponding to each facies juxtaposition type.[0U1] Clause 12: The method of any one of Clauses 1-11, wherein the one or more fault seal properties for the at least one fault plane comprise at least one of: a fault transmissibility multiplier(TM); dynamic measures of model connectivity; an average fault transmissibility; a fault sealing capacity; or a free water level.

[0112] Clause 13: The method of any one of Clauses 1-12, wherein the one or more petrophysical properties of the reservoir structure comprise at least one of porosity or permeability.

[0113] Clause 14: A processing system, comprising: a memory comprising computerexecutable instructions; and a processor configured to execute the computer-executable instructions and cause the processing system to perform a method in accordance with any one of Clauses 1-13.

[0114] Clause 15: A processing system, comprising means for performing a method in accordance with any one of Clauses 1-13.

[0115] Clause 16: A non-transitory computer-readable medium storing program code for causing a processing system to perform the steps of any one of Clauses 1-13.

[0116] Clause 17: A computer program product embodied on a computer-readable storage medium comprising code for performing a method in accordance with any one of Clauses 1-13.Additional Considerations

[0117] The preceding description is provided to enable any person skilled in the art to practice the various embodiments described herein. The examples discussed herein are not limiting of the scope, applicability, or embodiments set forth in the claims. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments. For example, changes may be made in the function and arrangement of elements discussed without departing from the scope of the disclosure. Various examples may omit, substitute, or add various procedures or components as appropriate. For instance, the methods described may be performed in an order different from that described, and various steps may be added, omitted, or combined. Also, features described with respect to some examples may be combined in some other examples. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects set forth herein. In addition, the scope of the disclosure is intended to cover such an apparatus or method that is practiced using other structure, functionality, or structure and functionality in addition to, or otherthan, the various aspects of the disclosure set forth herein. It should be understood that any aspect of the disclosure disclosed herein may be embodied by one or more elements of a claim.

[0118] As used herein, a phrase referring to “at least one of’ a list of items refers to any combination of those items, including single members. As an example, “at least one of a, b, or c” is intended to cover a, b, c, a-b, a-c, b-c, and a-b-c, as well as any combination with multiples of the same element (e.g., a-a, a-a-a, a-a-b, a-a-c, a-b-b, a-c-c, b-b, b-b-b, b-b-c, c-c, and c-c-c or any other ordering of a, b, and c).

[0119] As used herein, the term “determining” encompasses a wide variety of actions. For example, “determining” may include calculating, computing, processing, deriving, investigating, looking up (e.g., looking up in a table, a database or another data structure), ascertaining and the like. Also, “determining” may include receiving (e.g., receiving information), accessing (e.g., accessing data in a memory) and the like. Also, “determining” may include resolving, selecting, choosing, establishing and the like.

[0120] The methods disclosed herein comprise one or more steps or actions for achieving the methods. The method steps and / or actions may be interchanged with one another without departing from the scope of the claims. In other words, unless a specific order of steps or actions is specified, the order and / or use of specific steps and / or actions may be modified without departing from the scope of the claims. Further, the various operations of methods described above may be performed by any suitable means capable of performing the corresponding functions. The means may include various hardware and / or software component(s) and / or module(s), including, but not limited to a circuit, an application specific integrated circuit (ASIC), or processor. Generally, where there are operations illustrated in figures, those operations may have corresponding counterpart means-plus- function components with similar numbering.

[0121] The following claims are not intended to be limited to the embodiments shown herein, but are to be accorded the full scope consistent with the language of the claims. Within a claim, reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more.” Unless specifically stated otherwise, the term “some” refers to one or more. No claim element is to be construed under the provisions of 35 U.S.C. §112(f) unless the element is expressly recited using the phrase “means for” or, in the case of a method claim, the element is recited using the phrase “step for.” All structural and functionalequivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims.

Claims

CLAIMSWhat is claimed is:

1. A method of fault seal analysis, comprising: identifying at least one fault plane in a subsurface model representing one or more petrophysical properties of a reservoir structure; determining a plurality of facies juxtaposition types for the at least one fault plane, each facies juxtaposition type of the plurality of facies juxtaposition types identifying different facies pairs in contact along the at least one fault plane; estimating a fault rock permeability range for each facies juxtaposition type of the plurality of facies juxtaposition types; generating a plurality of candidate fault plane permeability scenarios, wherein for each candidate fault plane permeability scenario, a candidate fault plane permeability property is assigned to each facies juxtaposition type of the plurality of facies juxtaposition types using a simulation and the fault rock permeability range estimated for each facies juxtaposition type; for each candidate fault plane permeability scenario of one or more candidate fault plane permeability scenarios of the plurality of candidate fault plane permeability scenarios, determining one or more fault seal properties for the at least one fault plane using the plurality of candidate fault plane permeability properties assigned to the plurality of facies juxtaposition types for the respective candidate fault plane permeability scenario; and generating the one or more fault seal properties for the one or more candidate fault plane permeability scenarios for display on a computing device.

2. The method of Claim 1, wherein the simulation comprises a Monte Carlo simulation.

3. The method of Claim 1, wherein determining the one or more fault seal properties for the respective candidate fault plane permeability scenario comprises: calculating a fault transmissibility multiplier (TM) for the at least one fault plane using the plurality of candidate fault plane permeability properties assigned to the plurality of facies juxtaposition types for the respective candidate fault plane permeability scenario, wherein the fault TM is variable across the at least one fault plane; andgenerating dynamic measures of model connectivity using the fault TM.

4. The method of Claim 3, wherein generating the one or more fault seal properties for display on the computing device comprises generating a scatter plot based on the dynamic measures of model connectivity generated for each candidate fault plane permeability scenario of the one or more candidate fault plane permeability scenarios.

5. The method of Claim 3, wherein determining the one or more fault seal properties for the respective candidate fault plane permeability scenario comprises calculating an average fault transmissibility for the fault plane using the fault TM calculated for the respective candidate fault plane permeability scenario.

6. The method of Claim 5, wherein generating the one or more fault seal properties for display on the computing device comprises generating a pie chart for each of the one or more candidate fault plane permeability scenarios representing the average fault transmissibility calculated for the respective candidate fault plane permeability scenario.

7. The method of Claim 1, wherein determining the one or more fault seal properties for the respective candidate fault plane permeability scenario comprises: for each facies juxtaposition type: determining a fault sealing capacity using the candidate fault plane permeability property assigned to the respective facies juxtaposition type for the respective candidate fault plane permeability scenario and based on a hydrocarbon density and a brine density.

8. The method of Claim 7, wherein determining the one or more fault seal properties for the respective candidate fault plane permeability scenario further comprises: for each facies juxtaposition type: determining a free water level based on the fault sealing capacity determined for the respective facies juxtaposition type for the respective candidate fault plane permeability scenario.

9. The method of Claim 8, wherein generating the one or more fault seal properties for display on the computing device comprises: for each candidate fault plane permeability scenario of the one or more candidate fault plane permeability scenarios: generating for display the free water level determined for one or more facies juxtaposition types for the respective candidate fault plane permeability scenario based on a risk level associated with each of the one or more facies juxtaposition types being above a threshold risk level.

10. The method of Claim 9, wherein the risk level associated with each facies juxtaposition type is based on a threshold fault rock discontinuity risk.

11. The method of Claim 9, wherein the risk level associated with each facies juxtaposition type is based a type of facies juxtaposition corresponding to each facies juxtaposition type.

12. The method of Claim 1, wherein the one or more fault seal properties for the at least one fault plane comprise at least one of: a fault transmissibility multiplier (TM); dynamic measures of model connectivity; an average fault transmissibility; a fault sealing capacity; or a free water level.

13. The method of Claim 1, wherein the one or more petrophysical properties of the reservoir structure comprise at least one of porosity or permeability.

14. A processing system comprising: one or more memories comprising computer-executable instructions; and one or more processors configured to execute the computer-executable instructions and cause the processing system to:identify at least one fault plane in a subsurface model representing one or more petrophysical properties of a reservoir structure; determine a plurality of facies juxtaposition types for the at least one fault plane, each facies juxtaposition type of the plurality of facies juxtaposition types identifying different facies pairs in contact along the at least one fault plane; estimate a fault rock permeability range for each facies juxtaposition type of the plurality of facies juxtaposition types; generate a plurality of candidate fault plane permeability scenarios, wherein for each candidate fault plane permeability scenario, a candidate fault plane permeability property is assigned to each facies juxtaposition type of the plurality of facies juxtaposition types using a simulation and the fault rock permeability range estimated for each facies juxtaposition type; for each candidate fault plane permeability scenario of one or more candidate fault plane permeability scenarios of the plurality of candidate fault plane permeability scenarios, determine one or more fault seal properties for the at least one fault plane using the plurality of candidate fault plane permeability properties assigned to the plurality of facies juxtaposition types for the respective candidate fault plane permeability scenario; and generate the one or more fault seal properties for the one or more candidate fault plane permeability scenarios for display on a computing device.

15. The processing system of Claim 14, wherein the simulation comprises a Monte Carlo simulation.

16. The processing system of Claim 14, wherein to determine the one or more fault seal properties for the respective candidate fault plane permeability scenario, the one or more processors are configured to execute the computer-executable instructions and cause the processing system to: calculate a fault transmissibility multiplier (TM) for the at least one fault plane using the plurality of candidate fault plane permeability properties assigned to the plurality of faciesjuxtaposition types for the respective candidate fault plane permeability scenario, wherein the fault TM is variable across the at least one fault plane; and generate dynamic measures of model connectivity using the fault TM.

17. The processing system of Claim 16, wherein to generate the one or more fault seal properties for display on the computing device, the one or more processors are configured to execute the computer-executable instructions and cause the processing system to generate a scatter plot based on the dynamic measures of model connectivity generated for each candidate fault plane permeability scenario of the one or more candidate fault plane permeability scenarios.

18. The processing system of Claim 16, wherein to determine the one or more fault seal properties for the respective candidate fault plane permeability scenario, the one or more processors are configured to execute the computer-executable instructions and cause the processing system to calculate an average fault transmissibility for the fault plane using the fault TM calculated for the respective candidate fault plane permeability scenario.

19. The processing system of Claim 18, wherein to generate the one or more fault seal properties for display on the computing device, the one or more processors are configured to execute the computer-executable instructions and cause the processing system to generate a pie chart for each of the one or more candidate fault plane permeability scenarios representing the average fault transmissibility calculated for the respective candidate fault plane permeability scenario.

20. The processing system of Claim 14, wherein to determine the one or more fault seal properties for the respective candidate fault plane permeability scenario, the one or more processors are configured to execute the computer-executable instructions and cause the processing system to: for each facies juxtaposition type: determine a fault sealing capacity using the candidate fault plane permeability property assigned to the respective facies juxtaposition type for the respective candidate fault plane permeability scenario and based on a hydrocarbon density and a brine density.

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