Demonstration of an Efficient Concept-Selection Process for Tight and Unconventional Resources

Abstract

Summary Making an efficient and wise concept-selection decision—quickly selecting the right project—is often of equal or greater importance than later design and execution tasks for determining project success. An efficient assessment process is one that supports rapid assessment of an appropriately broad range of viable alternatives, leading to an optimized project design, while consuming the minimum necessary assessment resources. Value lost from a suboptimal-concept selection decision or from a needlessly prolonged assessment process is independent of value-generation opportunities during design and execution, and cannot be recovered during later project phases. The objectives of the methods shown in this paper are to improve concept-selection decision quality by allowing simultaneous optimization of interdependent development decisions, and to improve the quality of and reduce the resource requirements for simulation-derived production forecasts. This paper presents a complementary decision framework, productionforecasting process, and economic model that promote an efficient and high-quality concept-selection decision, and are particularly appropriate for early phase development concept selection and optimization for tight or unconventional resources. The method is suitable for both oil and gas resources, and is especially useful for assessing and developing large contiguous tracts. The decision framework is efficient because it is structured so that some decisions are independent of the simulation model, and those decisions can be optimized within the economic model. Our production-forecasting method is efficient because it uses small, symmetry-element reservoir-simulation models. The symmetry-element sector simulation models run fast and can evaluate many cases, but they still improve forecast quality by explicitly addressing many relevant physical effects that are not addressed by other methods that are attempting to model a much larger volume of the reservoir. The economic model is efficient because it includes an automated optimizer for those decisions that are independent of the simulation-derived forecasts, and it promotes high-quality decisions by incorporating meaningful constraints to ensure that the forecasts are both realistic and achievable. The economic model also includes a fracture efficiency factor that may be important for modeling the diminished performance observed as the number of stages increase in multifractured horizontal wells. This fracture efficiency factor may also be an important discriminator of performance between wells fractured by use of aqueous vs. nonaqueous fracturing fluids.