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Collaborating Authors
Results
Determining the Productivity of a Barrier Island Sandstone Deposit From Integrated Facies Analysis
Sharma, Bijon (Natl. Inst. for Petroleum and Energy Research) | Honarpour, M.M. (Natl. Inst. for Petroleum and Energy Research) | Jackson, S.R. (Natl. Inst. for Petroleum and Energy Research) | Schatzinger, R.A. (Natl. Inst. for Petroleum and Energy Research) | Tomutsa, Llvlu (Natl. Inst. for Petroleum and Energy Research)
Summary Two crossplot techniques, based on core-calibrated resistivity, porosity, and gamma ray (GR) logs, are described that distinguish barrier porosity, and gamma ray (GR) logs, are described that distinguish barrier island sandstones from genetically different nonbarrier sandstones in the Muddy sandstone reservoir in Unit A of Bell Creek field, Montana. The barrier island sandstones are separated further and grouped into two log facies, one consisting of highly productive facies (foreshore, shoreface, etc.) and the other, a less-productive facies (lower shoreface). The distinct crossplot patter for each facies group is due to similar petrophysical properties of each facies group resulting from deposition petrophysical properties of each facies group resulting from deposition within a unique depositional setting. Fluid production results from primary, secondary, and two EOR pilot projects indicate that in the barrier island reservoir at Bell Creek, projects indicate that in the barrier island reservoir at Bell Creek, the distribution of facies, with their characteristic reservoir properties and heterogeneities, dominates primary production, waterflood-sweep efficiency, distribution of residual oil saturation, and the performance of the chemical EOR pilot projects. Introduction The generally prolific production from oil and gas fields in barrier island clastic deposits results from the excellent porosity and permeability of sandstones deposited in relatively shallow, agitated permeability of sandstones deposited in relatively shallow, agitated marine waters. Sediments flanking main barrier sandstone deposits are organic-rich, lagoonal and deepwater, fine-grained deposits that often serve as excellent source beds for petroleum. Process-oriented sedimentological studies have provided better understanding of sedimentary structures, sequence of facies, and other features in different subenvironments that contribute to building barrier island sandstone deposits. Because each barrier island facies (beach, shoreface, dune, etc.) was deposited within a unique setting of wave energy, tidal range, and water depth, the sandstones from each subenvironment tend to have similar petrophysical properties (porosity, permeability, grain-size petrophysical properties (porosity, permeability, grain-size distribution, etc.) at the time of deposition. Davies et al. first demonstrated the remarkable similarity of internal structure and texture in different facies of the modern barrier island in Galveston, TX, with two ancient barrier complexes: one in the Lower Cretaceous of Montana and the other in the Lower Jurassic of England. A subsequent study revealed that major barrier island sandstone facies have recognizable characteristics and may also have some significant variations, depending on local wave conditions and tidal range. Recognizable characteristics of different facies of barrier island sand-stones have been investigated with thin-section analysis. Because of the relative uniformity of depositional processes in each facies, the predictability of fluid production from barrier island reservoirs can be greatly augmented from an understanding of the spatial distribution of thicknesses, flow properties, and geological heterogeneities in each facies. Subsequent to sandstone deposition, such secondary processes as diagenesis or tectonic events may severely affect the distribution of flow properties in different facies. Understanding depositional characteristics, however, leads to understanding the effect of secondary diagenetic processes. In this paper, we describe two crossplot techniques, based on interpretation of log and core data, that can effectively distinguish some of the barrier and associated nonbarrier island sandstone facies. We use these techniques to group facies with similar petrophysical properties, and then we study the different facies petrophysical properties, and then we study the different facies groups for distribution of reservoir properties and geological heterogeneities and variations in thickness and structure. The usefulness of facies interpretation for predicting productivity of sandstones in the different facies is demonstrated by a productivity of sandstones in the different facies is demonstrated by a qualitative comparison of initial primary and EOR production from Bell Creek field with the areal distribution of reservoir properties and sandstone geometry in the different facies groups. A primary objective of this investigation was to demonstrate that fluid injection and production predictions would be greatly improved if barrier island sandstone were divided into a number of facies or groups of facies with each group of similar facies characterized separately, instead of the average petrophysical properties of an entire sand-stone thickness being studied.
- North America > United States > Montana (1.00)
- North America > United States > Texas > Galveston County > Galveston (0.24)
- North America > United States > Wyoming > Wind River Basin > NPR-3 > Muddy Formation (0.99)
- North America > United States > Wyoming > Powder River Basin (0.99)
- North America > United States > Montana > Powder River Basin (0.99)
- North America > United States > Montana > Bell Creek Field (0.99)
- Reservoir Description and Dynamics > Reservoir Fluid Dynamics > Flow in porous media (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (1.00)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery > Chemical flooding methods (1.00)
- Reservoir Description and Dynamics > Formation Evaluation & Management > Open hole/cased hole log analysis (1.00)
Critical Heterogeneities in a Barrier Island Deposit and Their Influence on Various Recovery Processes
Sharma, Bijon (Natl. Inst. for Petroleum and Energy) | Honarpour, M.M. (Natl. Inst. for Petroleum and Energy) | Szpakiewicz, M.J. (Natl. Inst. for Petroleum and Energy) | Schatzinger, R.A. (Natl. Inst. for Petroleum and Energy)
Summary This paper synthesizes geologic information, acquired from the literature and field studies, and provides detailed maps of geologic heterogeneities, obtained from log and core data, of the Bell Creek field, MT. Geologic heterogeneities were correlated with fluid production data to identify the heterogeneities that have a dominant effect on fluid production. Integration of new and existing information from various geological, geophysical, and engineering disciplines allowed us to identify heterogeneities that influence production during different recovery operations. Introduction The shallow marine barrier-island/strand-plain deposystems are among the most important and are the habitat of at least six giant fields (with an ultimate recovery >100 million bbl [ 15.9 × 106 M3]) in North America. There is, therefore, considerable economic merit in research that provides an understanding of the magnitude and type of geologic heterogeneities likely to be encountered in exploitation of shallow marine barrier-island/strand-plain deposits. The distribution, continuity, and internal characteristics of marine sandstones are controlled by the depositional environment and tectonic setting, as well as by subsequent erosional, tectonic, and diagenetic processes. Understanding the depositional history of a reservoir helps to predict the genesis, distribution, magnitude, and frequency of occurrence of the various heterogeneities. The most important geological heterogeneities controlling fluid production are identified on the basis of a spatial description of reservoir fluid-flow properties and analysis of production performance and pressure distribution during different recovery stages. The barrier island oil field selected for analysis is Bell Creek field in Carter and Powder River counties, MT, on the northeastern flank of the Powder River basin (Fig. 1). This field, discovered in 1967, consists of six hydraulically isolated Lower Cretaceous Muddy sandstone reservoirs (Units A through E and Ranch Creek). The original oil in place (OOIP) for the field was calculated as 242.9 million STB [38.6 × 106 stock-tank M3] with an ultimate primary recovery of 48.4 million STB [7.69x106 M3] or 19.9% OOIP. A linedrive waterflood pattern began in Aug. 1970, and the ultimate secondary recovery from Unit A-the northernmost and largest of the six units-was estimated at 49.8 million STB [7.918 × 106 stock-tank m3], or about 39% OOIP. Two tertiary recovery pilot projects have been completed within Unit A since 1976. The northernmost pilot (Fig. 1) was only marginally successful because of unanticipated geologic complexity, while the southern pilot, implemented through the U.S. DOE Tertiary Oil Incentive Program (TIP), was more successful because it is in a more homogeneous part of the field. The characterization of Bell Creek field may help identify heterogeneities in similar barrier bar deposits from different geologic ages and geographic locations. For detailed geological and production-performance studies, we selected four sections from Unit A, including the TIP pilot area, as our 4-sq-mile [10.36-km2] study area (Fig. 1), and acquired log, well-test, production, and core data for detailed analysis. Influence of Geological Heterogeneities on Fluid Production Because of variations in the depositional and diagenetic processes, the effect of tectonic forces, and the variable interstitial fluid properties, the distribution of fluid-flow properties in a petroleum reservoir are rarely uniform. The nonuniform flow patterns are observed vertically in the reservoir pay zone and laterally in the sandstone deposit. "Heterogeneity" implies any change in geologic reservoir properties that causes a variation in fluid-flow parameters (e.g., permeability, porosity, fluid saturation, and capillary pressure) that results in modification of the flow regime. A spectrum of geologic heterogeneities affect fluid movement and oil recovery in reservoirs subjected to EOR. We restrict our analysis to those geologic heterogeneities that have a dominant effect on fluid production patterns in the barrier island sandstone studied. Earlier studies of barrier island and other sandstone deposits grouped the most important geologic heterogeneities affecting fluid production into three classes according to the different scales of the heterogeneities (Table 1). Muddy Formation Geology The Lower Cretaceous Muddy formation, which produces oil from Unit A in Bell Creek field, is composed of two genetically different, major sandstone reservoir units interpreted as barrier islands (littoral marine bars) and valley fills. The entire Muddy sandstone assemblage and its related depositional environments lagoonal, estuary, tidal flat, tidal channel, and valley fill) are under- and overlain by marine shales; i.e., Skull Creek and Shell Creek/Mowry shale, respectively. Hydrocarbon production in Unit A is controlled by at least five geological factors:stratigraphic relation of the barrier sandstones to the valley-fill deposits; development and architecture of the barrier island facies, such as internal distribution of facies within the dominant sedimentary cycle, and stacking or overlapping of subsequent fragmental cycles of barrier deposition; depth and width of erosional cuts into the top of the barrier island and their infilling type; distribution, type, and degree of importance of diagenesis (clay filling and compaction); and local faulting that appears to modify fluid flow patterns between individual wells and groups of wells. Depositional History. Paleogeographic and paleotectonic reconstructions of the Muddy formation show the interrelationship between continental (delta channels and deltaic plain), brackish marine lagoon, estuary, and tidal flat), and coastal marine (barrier islands) sedimentation in the northeastern Powder River basin where Bell Creek field is located. Incision of valley fills into the top of barrier deposits is commonly observed in Bell Creek cores, giving strong support to Weimer's concept that valley-fill deposits are stratigraphically younger than barrier island deposits. Therefore, in the Bell Creek area, the Muddy formation is a complicated system of barrier sandstones with channel cuts and subsequent valley-fills superimposed unconformably. This model finds numerous recent analogs along the Texas gulf coast and elsewhere. Holocene patterns of barrier island sedimentation in the U.S. indicate that valley-fill sediments, either underlying or incised into the tops of barrier island sandstone, commonly occur with barrier deposits and are typical of this type of near-shore sandstone deposit.
- North America > United States > Texas > Kleberg County (0.24)
- North America > United States > Texas > Chambers County (0.24)
- North America > United States > Montana > Powder River County (0.24)
- Phanerozoic > Cenozoic (0.68)
- Phanerozoic > Mesozoic > Cretaceous > Lower Cretaceous (0.45)
- Geology > Sedimentary Geology (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (0.76)
- North America > United States > Wyoming > Wind River Basin > NPR-3 > Muddy Formation (0.99)
- North America > United States > Wyoming > Powder River Basin (0.99)
- North America > United States > Montana > Powder River Basin (0.99)
- (2 more...)