Development of the 330-billion-bairel oil resource remaining in United States reservoirs after conventional primary and secondary recovery will be dependent on the advanced understanding of facies relations and compartmentalization inherent in reservoir depositional systems. Style of deposition, as reflected in internal reservoir architecture, defines flow units that determine how a reservoir drains, where hydrocarbons remain unrecovered at the interwell (macroscopic) scale, and what approaches will be effective in accessing unrecovered oil. A substantial part of the unrecovered oil resource is nonresidual oil that, although mobile in the reservoir, remains unrecovered owing to poor contact by existing wells and vertical or areal bypassing by the waterflood front.
Because heterogeneity style is a product of depositional system, it is predictable and can be characterized in terms from low to high in a lateral and vertical sense. For sandstones, the wave-dominated deltas, barrier cores, and sand-rich strand plains show a low degree of heterogeneity in both dimensions, whereas the highly aggradational backbarrier fans, fluvially dominated deltas, and fine-grained meander belts show a higher intensity of heterogeneity. Other systems can be similarly classified. The resulting matrix leads to delineation of targeted approaches to incremental oil recovery specifically tailored to the distribution of remaining oil saturation. Such approaches, optimized to the character of the depositional system, may include geologically targeted infill drilling, selective recompletion, horizontal drilling, and strategic cross-reservoir flooding involving flood redesign and profile modification. Such techniques are herein termed Advanced Secondary Recovery (ASR) and represent advancements in technology that will lead to near- and mid-term improvements in efficiency that set the stage for later approaches to Enhanced Oil Recovery (EOR).
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The Three-Dimensional Facies Architecture of Terrigenous Clastic Sediments and its Implications for Hydrocarbon Discovery and Recovery
While there has been much interest in recent years in concepts of sequence stratigraphy, this book focuses on stratigraphic units that are, in general, an order of magnitude smaller than sequences. A knowledge of such architectural detail is of considerable significance in the development of detailed, scaled facies models for depositional environments, and is of paramount importance in the efficient design of advanced petroleum recovery projects. This book is the outcome of a SEPM Research Symposium held at the annual meeting of the Society in San Antonio, Texas, April 1989. The intent of the meeting was to bring together modern research on facies architecture, and to apply this research to the investigation of reservoir heterogeneities and production problems.