A Pressure Transient Approach for Dynamic Characterization of a Giant Carbonate Middle Eastern Oil Field

Abstract

AbstractThis paper presents a comprehensive pressure transient analyses (PTA) based dynamic reservoir characterization of a mature giant carbonate oil field. An important part of an integrated reservoir study is to reconcile differences between the static and dynamic models. In this study, a large number of well tests were analyzed and integrated with other field data. The current study highlights the paramount importance of PTA for a refined reservoir description, including permeability modeling and characterizing intersecting or nonintersecting conductive fractures and faults across the field. This well tests data review has also broadened the field dynamics understanding along with the strengths of the synergic multidisciplinary approach as the PTA data is integrated with other reservoir characterization data types.The subject field is composed of two naturally fractured reservoirs separated by a thick non-permeable zone. The Upper reservoir is prolific, while the Lower reservoir is relatively tight and highly fractured. Early pressure data confirms communication between the two reservoirs through several large scale fractures crossing the thick non-permeable zone.For the purpose of this study, the field has been divided into several areas, with representative well data from both the Upper and Lower reservoirs. Pressure buildups from multi-well groups, generally conducted as single-phase (before water breakthrough), were analyzed by advanced analytical and/or numerical models. The selected interpretation model was dependent on the reservoir complexities diagnosed from the derivative plots. The analyses provided valuable well parameters, such as flow capacities and productivity indices, which are critical as input for permeability modeling and simulation model history-matching. Subsequently, equally important is the detection of reservoir description events that can be observed from the PTA response, e.g., areas of inter-reservoir communication, super permeability zones or quantification of fracture characteristic parameters. The presented case study includes well examples of the major observed field reservoir features.