Abstract

Simultaneous petroleum extraction operations, including drilling, completion, and production of tightly spaced horizontal wells are the inevitable reality in unconventional development. This next wave of development has just begun in the Midland Basin of West Texas, where operators are shifting from parent well tests to increased well density development. However, the development of increased well densities in a sequential, parent/child methodology commonly results in less effective stimulated rock volumes of child wells, increased production downtime, and drilling hazards. The key to maximizing corporate value will be in adopting development strategies that realize higher well densities while avoiding these pitfalls.

Here we present a case study of a novel multi-disciplinary approach aimed at the optimization of both surface and subsurface development operations for tightly-spaced and stacked stratigraphic intervals. Our methodology, here termed "Tank Development", aims to exploit a volume of rock at one time to maximize reservoir potential. The fundamental principle of Tank Development is maximizing well productivity by "super-charging" the reservoir prior to simultaneous initiation of production. Super-charging the reservoir is accomplished by sequencing hydraulic fracture operations and bringing all wells online simultaneously to pressurize the reservoir in an effort to create a demonstrably more complex fracture network. A surface microseismic array was used to monitor the completions of four horizontal wells in the Spraberry Formation. The results indicate evidence of breaking more rock when Tank Development is employed. Microseismic data also show an increase in near-wellbore fracture complexity for wells that were stimulated later in the Tank Development sequence.

The principle result from our tests is that productivity indexes for wells in our Tank Development program clearly exceed the productivity indexes for wells from the industry standard parent/child well development methodology. Thus, the new development approach has proven essential for maximizing asset value during simultaneous development of multiple horizons with horizontal wells in close proximity to one another. This multi-disciplinary development approach is key to optimizing near-wellbore fracture complexity and the conservation of completion energy required for increased well densities. In addition, Tank Development effectively eliminates the detrimental effects of parent and child well interactions. The surface and subsurface efficiencies maximize oil recovery and corporate value.

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