Multidisciplinary Approach for Targeting New Wells

Abstract

Summary Under currently known reservoir drive mechanisms, initial exploitation of a new field usually leads to drilling in several regions of the field for optimum production. As the field matures, it often is necessary to drill new wells to recover oil reserves trapped because of undetermined reservoir heterogeneity and not acknowledged during initial field development. Targeting new wells in a mature field is challenging because it calls for consensus among interdisciplinary groups (reservoir and production engineers, geoscientists, and drilling and facility engineers). The challenges usually involve estimating the cost and production of the new wells and finding convincing arguments that the existing wells will not drain the trapped reserves adequately. This paper provides a team approach to confront these challenges to target new wells in the mature Prudhoe Bay field. The field example shows that additional oil recovery was obtained with infill drilling. Introduction The large, unrecovered mobile oil resource base in the Prudhoe Bay field provides an immediate objective for additional recovery. A significant amount of oil was bypassed at the initial stage of field development because of a lack of knowledge of geologic information and reservoir heterogeneity (defined as the product of depositional and diagenetic processes and structural complexities). Therefore, as part of field depletion planning and to mitigate field decline, infill drilling of new wells often is proposed to increase recovery. In a large field, such as Prudhoe Bay, drilling new wells calls for interaction among professionals in several disciplines: reservoir, facility, environmental, production and drilling engineers, geoscientists, and petrophysicists. In addition, the field is divided into two operating areas. Therefore, cooperation with the partners also is required. As in other infill-drilling projects, the development plan for drilling new wells in the Prudhoe Bay field was addressed with a multidisciplinary team approach. Also, as in other optimization strategies reported in the literature, the team approach focused on targeting new wells to optimize the depletion plan.

Reservoir Characterization, Production Characteristics, and Research Needs for Fluvial/Alluvial Reservoirs in the United States

“…The first involved analysis of postfracture production performance of over 360 wells (Schuldt et al 1993). The second study involved an evaluation of infill drilling potential (Shirzadi and Lawal 1993). Results of the first study indicated that fractured wells show on the average a three-fold improvement in productivity.…”

“…Based on reasonable economic limits and constraints, the average additional recovery from these fractured wells wiI1be on the order of 250 thousand STB per well (SchuIdt et al 1993). The second study concluded that if infill wells are drilled on the existing 80-acre spaang in one of the older developed areas, the estimated overaI1 incremental oil recovery will be 2.1 rnilI.ionSTB (Shirzadi and Lawal 1993).…”