Layer | Fill | Outline |
---|
Map layers
Theme | Visible | Selectable | Appearance | Zoom Range (now: 0) |
---|
Fill | Stroke |
---|---|
Collaborating Authors
Saikia, Pabitra
Nested Models - New Workflows to Simulate Better Representation of Reservoir Heterogeneity, Within Data-poor Areas in a North Kuwait Heavy Oil Field
Freeman, Michael (Kuwait Oil Company) | Cheers, Michael (Shell Kuwait Exploration and Production B.V.) | Warrlich, Georg (Shell Kuwait Exploration and Production B.V.) | Zhang, Zhiyi Ian (Shell Kuwait Exploration and Production B.V.) | Saikia, Pabitra (Kuwait Oil Company) | Choudhary, Pradeep (Kuwait Oil Company) | Ahmad, Khalid (Kuwait Oil Company) | Ren, Zu Biao (Kuwait Oil Company) | Al-Dohaiem, Khalid (Kuwait Oil Company) | Al-Haqqan, Hamad (Kuwait Oil Company) | Al-Rashdan, Saad (Kuwait Oil Company) | Benham, Philip (Shell Kuwait Exploration and Production B.V.) | Al-Rabah, Abdullah (Kuwait Oil Company)
Abstract Within North Kuwait heavy oil fields, integrated reservoir modelling is challenged by inherent reservoir heterogeneities, regional non-stationarity (i.e. trends), asymmetrical well and seismic distributions, and the need to maintain alignment between various the model scales required and multiple purposes for which the models will be used. This paper presents a number of customized workflows adapted to characterize these reservoir architectures and heterogeneities within one field, appropriately at all model scales and in regions with variable well control. A reliable new rock type classification scheme was derived from cross plot analyses of Gamma Ray and Bulk Density (GR-DENS) logs. Within an initial production area containing over 900 regularly spaced wells, 3D variograms for these lithotypes were estimated, calibrated with 3D seismic and reservoir equivalent surface outcrops. The lithotypes were distributed into full field static models using these variograms and the Sequential Indicator Simulation (SIS) algorithm. An additional declustering step was implemented to express regional trends and account for asymmetrical data distribution. Petrophysical property modeling (shale volume, effective porosity, water saturation) was performed using the Kriging algorithm conditioned to lithofacies. From these full field models, sector models were created to capture geological heterogeneity at a smaller grid increment. Full-field facies were downscaled onto the sector model grids, and then the Sequential Gaussian Simulation (SGS) algorithm was used to interpolate petrophysical properties, constrained by histograms of the kriged background models. This allowed information from wells outside of sector models to be incorporated efficiently into them. The facies and heterogeneities represented within the full-field static models have improved upon earlier versions, by being distributed more consistently relative to known seismic and well control, and to outcrop reservoir analogues. Modelled petrophysical properties also show a more consistent linkage with known values derived from core analyses. This consistent set of models can now be used with greater confidence, to answer questions ranging from in-place volume uncertainties to dynamic production forecasting, to life of field development. This has also led to reduced dynamic model run times, and improved reservoir management and operations optimization. In summary a robust series of full-field and sector models was developed and customized to a North Kuwait heavy-oil field, with information from data-rich areas being elegantly applied to reduce uncertainties in data-poor areas. These nested models can now be matched to the detail required for the model purpose. For example heterogeneities that matter-for-flow in dynamic simulation models can be represented explicitly, whereas for full-field volume estimations property averages can be used.
- Asia > Middle East > Kuwait (1.00)
- Asia > Malaysia > Sarawak > South China Sea (0.28)
- Geology > Petroleum Play Type > Unconventional Play > Heavy Oil Play (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (0.47)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock (0.36)
- Geophysics > Borehole Geophysics (1.00)
- Geophysics > Seismic Surveying > Surface Seismic Acquisition (0.48)
A New Facies Classification Scheme Using Gamma Ray and Bulk Density Logs, With Multiple Practical Applications in North Kuwait Heavy Oil Fields
Freeman, Michael (Kuwait Oil Company) | Saikia, Pabitra (Kuwait Oil Company) | Benham, Philip (Shell Kuwait Exploration and Production B.V.) | Cheers, Michael (Shell Kuwait Exploration and Production B.V.) | Zhang, Zhiyi Ian (Shell Kuwait Exploration and Production B.V.) | Choudhary, Pradeep (Kuwait Oil Company) | Ahmad, Khalid (Kuwait Oil Company) | Zu Biao, Ren (Kuwait Oil Company) | Al-Dohaiem, Khalid (Kuwait Oil Company) | Al-Haqqan, Hamad (Kuwait Oil Company) | Al-Rashdan, Saad (Kuwait Oil Company) | Warrlich, Georg (Shell Kuwait Exploration and Production B.V.) | Al-Rabah, Abdullah (Kuwait Oil Company)
Abstract This paper presents a method for facies classification derived from cross plots of basic gamma ray and bulk density wireline log data. It has been specifically developed in-house for two North Kuwait heavy-oil fields, and has been calibrated against both field analogues and core sample measurements. This new facies classification scheme has proven to be quick and cost effective, with multiple practical applications for future field development and operation optimization. For two heavy oil fields in North Kuwait basic Gamma Ray and Bulk Density (GR-DENS) curve data from over 1300 wells were cross-plotted. The resulting relationship characteristics were used to delineate eight separate facies, which plot along a continuum from clean porous sands with little cement and clay, to less porous sands with increasing clay and cementation content, to carbonate and shale. The properties for these facies were calibrated against data from core analyses and with outcrop analogues in North Kuwait. These facies were populated into static reservoir models using the Sequential Indicator Simulation (SIS) method, and petrophysical modeling was then conditioned to these facies. These resulting modeled facies, with their associated petrophysical properties, have been used in a wide variety of subsequent analytical studies. The eight facies which have been newly delineated by the GR-DENS classification scheme capture the transitional nature of petrophysical properties for oil saturation, porosity and permeability. This has enabled several improvements for heavy-oil field development including: 1) better delineation of reservoir and baffle zones; 2) better calibration of oil saturation with core data; 3) calibration of facies with 3D seismic amplitude response; 4) better understanding of reservoir geomechanics and seal integrity assessment; 5) greater confidence in the results of static and dynamic reservoir modeling; 6) more effective decision making in the WRFM process; and 7) alignment of the petrophysical and facies characterization approach between two separate heavy oil asset teams, which allows for direct comparisons between their data sets. Although more complex software exists for specialized facies classification, the GR-DENS workflow newly developed for North Kuwait heavy oil has proven to be simple, rapid, accurate and cost effective. In summary a robust facies classification scheme was developed in-house which is appropriately customized for two North Kuwait heavy oil fields. This methodology has enabled the creation of more representative reservoir models, with resulting improvements in understanding for multiple aspects of both fields. These improvements in turn will lead to better production forecasting and optimization as well as enhance future life of field planning.
- Asia > Middle East > Kuwait (1.00)
- Asia > Malaysia > Sarawak > South China Sea (0.28)
- Geology > Petroleum Play Type > Unconventional Play > Heavy Oil Play (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (0.69)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (0.36)
- Geophysics > Borehole Geophysics (1.00)
- Geophysics > Seismic Surveying > Surface Seismic Acquisition (0.67)
- Geophysics > Seismic Surveying > Seismic Processing (0.48)
An Approach to Benchmark Summaries of Core Data and Procedures for North Kuwait Heavy Oil Fields, Against Similar Heavy Oil Operations in Other Countries
Saikia, Pabitra (Kuwait Oil Company) | Freeman, Michael (Kuwait Oil Company) | Choudhary, Pradeep (Kuwait Oil Company) | Tyagi, Aditya (Kuwait Oil Company) | Zhang, Zhiyi Ian (Shell Kuwait Exploration and Production B.V.) | Benham, Philip (Shell Kuwait Exploration and Production B.V.) | Warrlich, Georg (Shell Kuwait Exploration and Production B.V.) | Gomez, Fernando (Kuwait Oil Company) | Al-Terki, Abdulrazaq (Kuwait Oil Company) | Ahmad, Fatma (Kuwait Oil Company) | Ahmad, Khalid (Kuwait Oil Company) | Al-Wael, Hamad (Kuwait Oil Company) | Taqi, Fatma (Kuwait Oil Company) | Al-Boloushi, Ahmad (Kuwait Oil Company) | Al-Doub, Abdulaziz (Kuwait Oil Company) | Al-Rabah, Abdullah (Kuwait Oil Company)
Abstract Challenging aspects to heavy oil field development are the large volume of data which is collected, in particular from cored evaluation wells, and the difficulty in evaluating of the quality of such data. This paper outlines an approach to summarize coring data and procedures from two heavy oil fields in North Kuwait, and then to compare those summaries with similar heavy oil operations in other countries, in order assess their quality and degree of representativeness. For two North Kuwait heavy oil fields, data was tabulated for the cumulative amounts of core cut and recovered relative to their field areas. This data was then further analyzed to summarize recovery by rock type, and assess the quality and quantity of plug samples collected. Benchmarks were established by summarizing core data from similar heavy oil operations in other countries, and the North Kuwait heavy oil data was then compared with those benchmarks. In a similar manner, documented core handling procedures for North Kuwait Heavy Oil operations were compared with procedures from similar heavy oil operations in other countries. The benchmarks which were used to compare North Kuwait Heavy Oil data summaries with other countries include the following: 1) Coring Well Area Coverage Densities; 2) Coring Well Vertical Coverage of Cap Rock and Reservoir Intervals; 3) Core Plug Sample Rate and Survival Rate; and 4) Core Handling Procedures and Volume of Coring. For many of the benchmarks used, North Kuwait heavy oil operations compare favorably with similar operations from other countries. However areas of improvement were identified from these benchmarks in terms of areal core coverage, vertical core coverage, core plug rates and core handling procedures. It is expected that these improvements, when implemented, will lead to a more representative sampling of the areas and rock types (reservoir rocks, baffles and cap rocks) in North Kuwait. This in turn should lead to a better understanding of fluid volumetrics, reservoir characterization and subsequent life of field development. As well by applying a focused approach to future coring operations, a significant cost savings is expected relative to original evaluation well plans. A significant product from this study is a large summary database of all coring information for two North Kuwait heavy oil fields, which can be queried by area, rock type and sample type. This data base has been compared with similar operations in other countries using a series of benchmarks. Planned future coring and sampling operations have been modified through the use of this benchmarking tool.
- Asia > Middle East > Kuwait (1.00)
- Asia > Malaysia > Sarawak > South China Sea (0.28)
- Geology > Petroleum Play Type > Unconventional Play > Heavy Oil Play (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (0.47)
- North America > United States > Alaska > North Slope Basin > Orion Field > Schrader Bluff Formation (0.99)
- North America > Canada > Alberta > Western Canada Sedimentary Basin > Alberta Basin > Cold Lake Field > Clearwater Formation > 995053 2D Cold Lake 2-10-63-2 Well (0.99)
- Asia > Middle East > Israel > Mediterranean Sea > Southern Levant Basin > Or Field (0.99)
- North America > Canada > Alberta > Athabasca Oil Sands > Western Canada Sedimentary Basin > Alberta Basin > Orion Oil Sands Project (0.94)
Analytical and Numerical Models Assist in Water Production Management in a Heavy Oil Reservoir in Northern Kuwait
Al-Shammari, Asrar Ajaimi (Kuwait Oil Company) | Kharghoria, Arun (Kuwait Oil Company) | Garcia, Jose Gregorio (Kuwait Oil Company) | Saikia, Pabitra (Kuwait Oil Company) | Al-Shammari, Abdulrahman Fares (Kuwait Oil Company) | Al-Rabah, Abdullah Abdul (Kuwait Oil Company) | Husain, Hisham (Shell) | Kalia, Devesh (Shell)
Abstract A comprehensive numerical and analytical assessment of water coning in a heavy oil field in Northern Kuwait is presented in this study. Several wells were investigated in light of possible coning affect. Based on the lessons learned from the field data and modeling efforts, a coning envelope is generated and possible mitigation actions are explored. The complex geologic and stratigraphic architecture of the reservoir with underlying oil-water contact presents a unique challenge to achieve water-free oil production in this field. The field produces average 15 API crude of 50-100 cp at 100° F. Production data from wells from different structural locations were history-matched using numerical simulations on single well models (including type well models). Model runs were extended to estimate critical liquid rate to avoid coning. Additionally, critical rates assessed from several analytical models were compared against those from the numerical simulations. Critical liquid production rates for different areas of the field have been assessed based on the coning envelope generated. Further works showed that the critical rate is also a strong function of operational, reservoir and fluid parameters as well as completions standoff from current oil-water contact (OWC). Since the current oil API is very close to that of water, the critical rate is not a strong function of the density difference of the reservoir fluids, however, difference in the fluid viscosities displayed a some degree of impact on the coning rate. Operational results also showed that average of 15 ft standoff from the existing OWC is critical to avoid imminent coning. This presents an important opportunity for efficient completion decisions of a candidate well. The most significant new finding is that two analytical models evaluated during this study indicated that these models have limited capability to assess the critical rate from the heavy oil reservoir, and appear to have high degree of sensitivity to oil viscosity. This paper provides an integrated approach to assess and manage water cone in a heavy oil recovery project. Generated coning envelope provides a tool for a proactive strategy for rate management including opportunities for strategic well completion decisions. Another noteworthy assessment is that the existing analytical models have significantly limited capability to model water coning behavior in a heavy oil reservoir.
- North America > United States (1.00)
- Asia > Middle East > Kuwait (1.00)
- Geology > Petroleum Play Type > Unconventional Play > Heavy Oil Play (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock (0.31)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Oil sand, oil shale, bitumen (1.00)
- Reservoir Description and Dynamics > Reservoir Simulation (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization (1.00)
- Production and Well Operations > Well Operations and Optimization (1.00)
Integrated Approach for Evaluation of Free Gas Distribution Assists in Improved Well Management Practices in a Northern Kuwait Heavy Oil Field
Saikia, Pabitra (Kuwait Oil Company) | Al-Rashdan, Saad (Kuwait Oil Company) | Taqi, Fatma (Kuwait Oil Company) | Al-Dohaiem, Khalid (Kuwait Oil Company) | Al-Rabah, Abdullah (Kuwait Oil Company) | Tyagi, Aditya (Kuwait Oil Company) | Choudhary, Pradeep (Kuwait Oil Company) | Ahmad, Khalid (Kuwait Oil Company) | Kharghoria, Arun (Kuwait Oil Company) | Malik, Satinder (Shell Kuwait Exploration and Production B.V.) | Zhang, Ian (Shell Kuwait Exploration and Production B.V.) | Cheers, Mike (Shell Kuwait Exploration and Production B.V.)
Abstract Free gas along with heavy oil production affects the progressive cavity pump (PCP) performance. This necessitates the strategy to perforate away from the free gas zone. To be able to do this, it requires an integrated approach to evaluate and map the spread of the free gas accumulation in the field. The paper shall present how this resulted in improved well performance with less free gas interference. The methodology included the understanding of the production data, sub-surface geology and petrophysics; reservoir heterogeneity and free gas presence from wireline logs, core data and isotope analysis of gas collected during mud-logging and creation of maps and cross-sections showing both vertical and aerial spread of free gas accumulation. This was then integrated with existing production and well management practices, along with numerical simulation results. Such in-depth analysis helps to bring significant changes in well completion strategy and is a vital contribution to the WRFM strategy. Unlike in conventional fields where depth is more and buoyancy pressures are large, gas can easily displace oil to accumulate in structural highs, in shallow heavy oil fields, free gas accumulation is a result of combination of structural and stratigraphic entrapment process. Vertical migration and lateral migration of gas is likely restricted by non-reservoir facies. As a result a consistent gas-oil contact (GOC) may not be present across large distances. Gas oil contact separates heavy oil by possible structural spill point and lithological boundary, dipping from south to north. Structurally higher areas are prone to localized gas accumulation. The completion stand-off from the gas base has a direct correlation with gas production. So the well management and production practice is to increase the stand-off from gas base to top perforations in future wells and to perform gas shut-off job in current wells to avoid free gas production. The novelty of the current approach is that it will proactively help in completion strategy to reduce future free gas production, subsequent loss in natural reservoir energy and maintain the oil production target.
- Geology > Petroleum Play Type > Unconventional Play > Heavy Oil Play (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock (0.69)
- Well Completion > Completion Installation and Operations (1.00)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Oil sand, oil shale, bitumen (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (1.00)
- Reservoir Description and Dynamics > Formation Evaluation & Management > Open hole/cased hole log analysis (1.00)
Cost-Effective Improvement of Core Analysis for Heavy Oil Development in Northern Kuwait
Ahmed, Khalid (Kuwait Oil Company) | Tyagi, Aditya (Kuwait Oil Company) | Saikia, Pabitra (Kuwait Oil Company) | Taqi, Fatma (Kuwait Oil Company) | Al-Rabah, Abdullah (Kuwait Oil Company) | Appel, Matthias (Shell) | Benham, Philip (Shell) | Zhang, Ian (Shell) | Mani, George (Core Lab) | Luague, Jefferson (Corpro)
Abstract Routine and Special Core analysis (RCAL and SCAL) are the cornerstone of Petrophysics Modeling and Formation Evaluation. In order to obtain the required information, it is important to have quality core, its processing and analysis. This paper summarizes current practices vis-à-vis improvements made in key technical areas. Coring and core analysis are cost-intensive processes. Only quality data from representative core plugs can offset the high cost and can help to achieve the objectives of coring and core analysis. To obtain consistent quality core plugs, coring practice, on-site handling and plugging procedure have to be the best in class. Coring and core analysis in the shallow-depth Heavy Oil Fields in Northern Kuwait have been in place for some time. The processes like i) coring operation ii) on-site core handling and preservation iii) core slabbing iv) core plugging and finally v) core analysis are continually improved. In order to be efficient and cost-effective, all the above processes were re-visited, quality gaps identified and improvements implemented by incorporating unconsolidated formation characterization from the available extensive petrographic studies. For example in the coring practice front, coring and core handling protocols were modified for sour heavy oil-bearing formations noticed in parts of the fields. On-site dry ice was used in addition to the prevalent practice of normal freezing. In the laboratory analysis front, obtaining representative plugs and getting useful results from them were the key challenges. Compared to the previous practice of liquid N2 injection from top only during core slabbing by band saw, liquid N2 injection from both top and bottom resulted in improved core integrity. The previous practice of plunge cutting of plugs with liquid N2 was continued. Before any analysis, Computer Tomography (CT) scan of the plugs was performed to discriminate plug-integrity related issues. This paper discusses lessons learnt from past coring and core analysis processes and their impact on heavy oil development. Improvements to these processes as cost-effective measures are presented through real examples. Recommendations for improvement include field procedure, laboratory process, and usability of the tests performed, which may be useful to the industry where heavy oil core analysis is used.
- Geology > Petroleum Play Type > Unconventional Play > Heavy Oil Play (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock (0.50)
- Energy > Oil & Gas > Upstream (1.00)
- Materials > Chemicals > Commodity Chemicals > Petrochemicals (0.32)
Decision-Based Modeling: Linking Subsurface Modeling Strategies to Business Decisions in KOC's Viscous Oil Field Developments
Al-Dohaiem, Khalid (KOC) | Warrlich, Georg (Shell) | Cheers, Mike (Shell) | Reijnders, Gert-Jan (Shell) | Jha, Madan (KOC) | Bagheri, Mohammad Ali (KOC) | Saikia, Pabitra (KOC) | Zhang, Ian (Shell)
Abstract When developing and operating oil and gas fields, a large number of engineering decisions need to be taken. These decisions range from the very high-level such as recovery mechanism, facility sizing or well count to more detailed decisions such as individual well placements, well design and completion strategies. Typically, subsurface models play a role in informing these decisions by testing their effect on forecasted production and it is generally held best practice to test them against a wide range of subsurface conditions, a range that expresses the envelope of subsurface uncertainty. Whilst these commonly held objectives are more or less universal, selecting an appropriate subsurface modelling strategy (i.e. what to model & how to model it) to achieve these objectives usually generates more divergent views. Whilst there are always various valid modelling approaches available which are both geologically and numerically valid, a good modelling strategy pays close attention to the type of the specific decisions being taken for the project and the accuracy required to take those decisions. To align these views, in decision-based modelling, business decisions and their timing were mapped to the models needed to make the estimates that inform them. Dialogue between the disciplines established the accuracy required for these estimates, and these discussions often revealed surprising opportunities to simplify processes and accelerate delivery. The outcome is a common view on a decision-driven modeling strategy that enables business decisions to be taken efficiently. This strategy, and the subsequent delivery plan that is developed from it is seen as a key to success. This paper describes the decision-based approach taken in the subsurface modelling required to support quality development decisions for the development of two of KOC's Heavy oil fields through the Enhanced Technical Service Agreement (ETSA) between Shell and KOC. In this particular application of the process, the suite of models to be built has been mutually agreed at the start by the integrated development team through a structured collaborative workshop, or Model Framing Event. A fullfield and a sector model for 2 different fields are discussed to exemplify the link between required decision and supporting modelling approach.
- Geology > Rock Type > Sedimentary Rock > Clastic Rock (0.71)
- Geology > Petroleum Play Type > Unconventional Play > Heavy Oil Play (0.56)
- Geology > Sedimentary Geology > Depositional Environment > Transitional Environment (0.47)
Origin of Cement, Diagenesis and its Role in Fluid distribution in Shallow Heavy Oil Unconventional Reservoir in Kuwait
Choudhary, Pradeep Kumar (Kuwait Oil Company) | Al-Rashdan, Saad (Kuwait Oil Company) | Ferdous, Hasan (Kuwait Oil Company) | Saikia, Pabitra (Kuwait Oil Company) | Ahmed, Khalid (Kuwait Oil Company) | Ahmad, Fatma (Kuwait Oil Company)
Abstract A shallow unconventional heavy oil reservoir in Kuwait is primarily an unconsolidated sandstone reservoir with intervening cemented siltstone and sandstone, and thin shale layers. The process and relative timing of cementation in the reservoir played a key role in fluid distribution as the pore-filling cements originated prior to oil migration. Moreover, oil migration into the cemented zones was prevented by the presence of cement. This paper presents a study based on over 100 logs and 10 conventional cores in north of the reservoir. Detailed core analysis including petrography, XRD and SEM studies were considered understand the origin of cement, diagenesis and role in fluid distribution. In terms of origin and diagenesis, three types of cements were identified namely Calcite, Dolomite, and Argillaceous. Calcite and Dolomitic cements are admixture of calcium carbonate and calcium-magnesium carbonate with argillaceous components. Argillaceous cement is dominated by illite-montmorillonite and palygorskite with minor amount of kaolinite and chlorite. Argillaceous one primarily originated from feldspar, calcite from meteoric water rich in dissolved calcium (gypsum) and Dolomite as replacement of precursor calcite. Cement plays different roles in fluid distribution. Argillaceous cements cause pore-throat blockage due to presence of illite and palygorskite that form filamentous-fibrous aggregates. Cemented layers act as baffles in between oil layers capable of producing significant amount of trapped water in low pressure regime as they have significant amount of porosity and permeability. Finally cement layers hold water due to high capillary pressure and act as "water above oil" behaving as thief zone during thermal steam operation. Understanding origin of cement, diagenesis and its role in fluid distribution assist in evaluation of the layered nature of this complex fluid distribution pattern reservoir. Finally, integration of depositional environment, lithofacies, and cement distribution greatly enhance the assessment of lateral extension and characterization of these type of reservoirs.
- Geology > Sedimentary Geology (1.00)
- Geology > Mineral (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (0.56)
Integrated Rock-Typing Workflow in Shallow Unconventional Reservoir in Kuwait
Saikia, Pabitra (Kuwait Oil Company) | Shanat, Faisal (Kuwait Oil Company) | Ahmed, Khalid (Kuwait Oil Company) | Choudhary, Pradeep (Kuwait Oil Company) | Ferdous, Hasan (Kuwait Oil Company) | Ahmed, Fatma (Kuwait Oil Company) | Fournier, Frédérique (Beicip-Franlab)
Abstract Heterogeneous lithofacies distribution resulting into a complex rock-type model in shallow unconsolidated reservoir has a direct role on fluid distribution and trapping mechanisms. A systematic evaluation of these rock-types is necessary for proper reservoir characterization and modeling. In reality, the lithofacies leading to rock-types act as the building blocks to construct a realistic static model, which serves in the understanding of the dynamic behavior of the reservoir. During this study, 202 wells were selected across the field to capture the vertical and lateral heterogeneity of the reservoir, out of which 93 wells have cores. During a first step, a lithofacies prediction model was created from the core sedimentological description, X-Ray Diffraction (XRD), and wireline logs (raw and mineralogical logs) using probabilistic classification schemes. In a second step, petrophysical data like Routine Core Analysis (RCAL), Mercury Injection Capillary Pressure (MICP), were included to build rock-types associated with the different lithofacies. This integration workflow has resulted in a robust lithofacies and rock-type model consisting of nine lithofacies and five rock-types respectively. It was also noticed that silty non-pay and marginal pay reservoir have inadequate MICP data. Subsequently, two wells were selected and MICP data will be collected for improved and more confident modelling in future. This model assists to predict lithofacies and rock-types in un-cored wells provided a set of relevant logs are available. The integrated workflow ensures that the lithofacies and rock-types determined at the wells are consistent all over the study area. The identified lithofacies and rock-types will add great value in building a realistic reservoir static model since they are able to explain the fluid distribution pattern and the concept of barriers and baffles in the reservoir. This will also assist in optimized perforation and completion plans for the reservoir. Ultimately, the input data are readily available for future field-intensive reservoir characterization.
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (0.31)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock (0.31)
Sand body Architecture Predictive Model using Sequence Stratigraphy for Proper Thermal Recovery of Unconventional Resources in Kuwait
Llerena, Javier (Kuwait Oil Company) | Ferdous, Hasan (Kuwait Oil Company) | Choudhary, Pradeep (Kuwait Oil Company) | Saikia, Pabitra (Kuwait Oil Company) | Bora, Deepender (Schlumberger) | Ali Lahmar, Hakima (Schlumberger)
Abstract Shallow poorly-consolidated viscous oil bearing sandstones in Kuwait were deposited in a complex fluvio-deltaic environment that was episodically influenced by estuarine-transitional-marine settings. Ongoing reservoir characterization is uncovering high matrix contents along with various cement phases, predominantly calcite, dolomite, and clay minerals that control the pore-networks with inter-granular primary porosity and generation of secondary pores, thus impacting the overall lithofacies and fluid flow-path used to design the development strategy. A high-resolution Sequence Stratigraphy model revealed the dominant lowstand and highstand-transgressive depositional regimes for reservoir development. In the model sand bodies commonly represent multi-stacked fluvial to distributary channel-fills and associated facies resulting with variable degree of fluid saturations. Using Sequence Stratigraphy first time, for an unconventional oil reservoir in Kuwait, this model is aimed to: 1) improve the understanding of depositional facies, evolution and distribution of reservoir sand trends within a chronostratigraphic framework, and 2) address the predictability of lateral and vertical complexity and distribution of the reservoir/non-reservoir Lithofacies. A Gamma Ray/Density model was built in Petrel® software module, allowing creating a log-based property model and applied it to a set of logs, defining 11 lithofacies which have been calibrated with sedimentary core descriptions and divided in three categories; pay reservoir, non-pay reservoir (cemented baffles) and non-permeable facies. Discontinuous shale/siltstone/cemented baffles would act as thief zones and may cause cross-formational flow and conductive heat loss; this must be taken into consideration for thermal recovery strategy. The developed Sequence Stratigraphy model has established a pattern of Systems Tracts that would address to define the lateral and vertical complexity and distribution of the reservoir lithofacies, and the model would provide a greater ability to identify and predict individual pay and non-pay zones with inherent rock lithologies and heterogeneity to result in a predictive sand-architecture framework for proper thermal development.
- North America (0.93)
- Asia > Middle East > Kuwait (0.92)
- Information Technology > Data Science > Data Mining (0.50)
- Information Technology > Modeling & Simulation (0.40)