Developing Performance Estimates of the Heterogeneous Upper Sands of the Greater Burgan Field Using Part Field Models (Part 2)

The Burgan Sands constitute the major reservoir in the giant Greater Burgan field. The Upper Burgan Sands contain significant volumes of oil, several billions of barrels, and have generally poorer and more variable reservoir quality and poorer continuity than the bulk of the Burgan sequence. Secondary water flooding is currently under consideration. This paper describes the challenges in developing part field models that are appropriate for waterflood simulation studies and that are, as far as is practicable, conditioned to the available dynamic data. The general approach to choosing "type areas" to represent typical portions of the field will be described. The process of developing geo-cellular models and conditioning them to dynamic data will then be illustrated. The existing geological and simulation models are considered too coarse to provide a proper basis for modelling the Upper Burgan. The extent to which this resolution has allowed geological models to be conditioned to dynamic data has been limited. A rock typing exercise integrated available core, log, and production data. Speed zones and flow barriers were identified. Calculated flow capacities and productivity indices generally matched field data well. Pressure breaks in the RFT profiles correlated well with vertical flow barriers. In addition, Permeability anisotropy ratios (Kv/Kh) were developed from detailed RCA and probe permeameter data acquired in key wells. Subsequently, MicroModels at whole core scale were developed and simulated to generate representative Kv/Kh ratios by Facies. Based on sedimentology studies and rock typing work, and the existing structural model, detailed geo-cellular models were produced. Dynamic models were then developed and conditioned to selected dynamic data. The approach used to condition these models to pressure transient data, local water movement as indicated by a detailed water encroachment survey, and to the pressure breaks seen on RFTs is described. This process both confirmed the plausibility of the geo-model and reduced uncertainty in permeability anisotropy. The field was segmented into equi-uniform polygons, on which waterflood patterns were evaluated, number of wells and throughputs determined, and the volumes of water to be handled estimated. A series of numerical simulation models were developed, through variations on the reservoir quality, reservoir connectivity, oil type, and development options. Generated water-cut vs. recovery factor profiles were utilized in a hybrid approach combining analytic and numerical evaluations to determine production profiles and potential waterflood recovery factors over time for each of the polygons, and the whole field. The work demonstrates a methodology by which relatively quick but comprehensive and robust evaluation of the potential value of a waterflood development could be made. It allows for sensitivity assessments and a degree of optimization.

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Developing Performance Estimates of the Heterogeneous Upper Sands of the Greater Burgan Field Using Part Field Models

Muhammad

Ortegon

Ibrahim

et al. 2015

Day 3 Wed, September 16, 2015

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The Burgan Sand reservoir is the largest and most prolific reservoir in the Greater Burgan field in Kuwait. As development of this reservoir proceeds, greater attention is being paid to the more heterogeneous upper part of the reservoir, the Upper Burgan Sands, which contain significant, multi-billion barrel, resources. A conceptual Field Development Plan was developed to enable an assessment of performance under waterflooding. Due to the complexity of the Upper Burgan Sands and the very large areal extent of the Greater Burgan field, it was considered impractical to model the reservoir in appropriate detail in the full field simulation model. An alternative modeling approach was adopted. This involved developing a number of part field geological models which were subsequently used to develop high resolution dynamic simulation models. This paper describes the challenges of choosing an appropriate range of part field models that capture variation in geological characteristics and of hydrocarbon properties, conditioning these models to available dynamic data and accounting for the historical production. Particular attention is paid to three problems. First, to rank the models in terms of key features that would be expected to govern reservoir performance. These included internal heterogeneity, average reservoir quality, connectivity to the underlying Middle Burgan Sands and variation in fluid properties. Second, to assign the selected models to represent different parts of the reservoir. Third, to ensure that historical performance, including water influx inferred from surveillance data, is accounted for in predicting future performance. The estimates were determined by a hybrid formulation, combining an analytic and simulation approach, suited for rapid computations and multi-scenario generation. Simulation results of water-cut versus recovery have been integrated with standard analytic expressions for fully developed pattern waterfloods. Scenarios investigated include the determination of ultimate recovery, a phased out recovery according to production and sweep of lower intervals, sensitivities to drilling rate, and a waterflooding scheme prioritized on area production potential. Based on the results from the part field models, performance estimates of the Upper Burgan Sands reservoir have been made. Volumes forecasts and associated well numbers have been predicted. A new reservoir simulation and analytical formulation has been developed to enable rapid predictions of waterflood scenarios. The hybrid formulation has proved to be significantly faster, resulting in a much quicker turnaround time compared to a traditional simulation study.

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Developing Performance Estimates of the Heterogeneous Upper Sands of the Greater Burgan Field Using Part Field Models (Part 2)

Cited by 3 publications

References 4 publications

Capturing Multiscale Heterogeneity in Paralic Reservoir Characterization: A Study in Greater Burgan Field, Kuwait

Capturing Multiscale Heterogeneity in Paralic Reservoir Characterization: A Study in Greater Burgan Field, Kuwait

Challenges in Developing Part Field Models to Assess Waterflood Performance for the Upper Burgan Reservoir, Greater Burgan Field, Kuwait

Developing Performance Estimates of the Heterogeneous Upper Sands of the Greater Burgan Field Using Part Field Models

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