Technology Update: Leveraging Subsurface Insight, Screening, and Diversion Technology in Refracturing

Abstract

Technology Update A challenging commodity price environment has forced operators to seek methods for sharply lowering recovery cost per barrel of oil equivalent (BOE) in unconventional plays. Some reduced costs have resulted from the overcapacity of global services. Other reductions have resulted from declining industry activity, which has increased the availability of personnel and led to a renewed focus on maximizing drilling and completion (D&C) process efficiency. A portion of the recovery cost reduction has resulted directly from incremental technical innovations and process improvements that were difficult to achieve when operators and service companies were concerned chiefly with D&C execution. Older processes were designed to maximize early production, whereas a number of newer technologies focus on maximizing net present value (NPV). High NPV is most often achieved by reducing uncertainty and manipulating the cost portion of the NPV equation, especially when the commodity price and/or discount rate is uncontrollable. D&C portfolios have primarily contained a mix of delineation wells and development wells. Delineation wells have a higher cost per BOE but a higher potential for accelerating reserve recovery. Development wells have a lower cost per BOE but a lower potential for accelerating recovery. This mix of wells is appropriate for periods when margins are high enough to cover the associated D&C costs. However, the loss of such margins in a low-price environment has prompted adjustments to lower the average cost per BOE. One strategy for lowering that cost is to increase the percentage of refractured wells in a portfolio. Typically, the cost per BOE of refracturing is substantially lower than that of drilling and completing delineation or development wells. Recently, the development and implementation of effective stimulation diversion techniques and greater focus on candidate screening have narrowed the window of uncertainty in executing refracturing operations in horizontal wells. These improvements have reduced the economic risk of these operations and created further incentive to shift portfolio strategies toward refracturing. Taking advantage of refracturing opportunities in a portfolio involves four steps. Screen the best candidate properties, based on reservoir quality and the potential to exceed the original completion quality. Design the optimal refracture treatment to place new conductive fractures where desired and reconnect existing ones. Execute the refracture treatment for coverage of all selected lateral areas, using the latest processes, techniques, and materials. Diagnose the refracture performance and optimize the refracture design for analogous properties, using state-of-the- art diagnostic tools. This article primarily discusses the candidate selection process.