Throughout the past several years, economic and technological advancements in the North American shale market with respect to drilling and hydraulic-fracturing operations have helped create a “typical” operating scheme for producing from the multiple shale-formation reservoirs currently being exploited. This typical scheme focuses on operational efficiency and cost reduction to drive profitability in these markets. Although operational efficiency and effective cost control have led to more-profitable operations in these shale reservoirs, the unknowns regarding the subsurface of these highly complex formations can often create situations of operating without sufficient information to optimally design drilling-and-completions strategies to produce larger volumes of hydrocarbon from the reservoir.
Opposed to conventional operations, the amount of basin and asset knowledge being collected and developed in most of these shale plays is much lower, and thus can result in poor development decisions, leading to less than optimum economic performance. Focus on subsurface knowledge as well as collaboration between the various aspects of developing an asset is essential to helping discover and produce more oil and gas from these complex reservoir systems.
This paper examines a case study of three wells in Wise County, Texas, in the Barnett shale, where a collaborative subsurface insight investigation and a drilling-and-completions optimization process were used to illustrate the production benefit achieved through improved reservoir understanding. Within this process, an asset Earth model was created with the collected information from wireline logging, logging while drilling, core testing, mechanical rock and fluid properties, formation mineralogy, and wellbore-image logging. In addition, for the completions-design strategy, microseismic measurement and image-log fracture matching and complex-fracture modeling software tools were used to define and model the growth of the stimulated fracture network during hydraulic-fracturing completions.
This paper presents an overview of “typical” previous completions and subsurface information collected before implementation of the new process in comparison to changes made to the drilling-and-completions designs used on three wells, as well as an overview of the types of information collected to supply the Earth model. Examples of the fracture matching and complex-fracture modeling for the wells help illustrate the design and optimization of hydraulic-fracturing treatments in a complex shale reservoir. Finally, a production-results comparison is presented to illustrate a significant increase to production of hydrocarbon through better reservoir understanding and drilling-and-completion designs.