Use of Horizontal Well Image Tools To Optimize Barnett Shale Reservoir Exploitation

Abstract

Abstract Horizontal wells represent a growing percentage of the drilling activity in low permeability reservoirs within the United States. With effective stimulation techniques, these wells have demonstrated favorable economics compared to vertical wells in the same reservoir due to the much larger hydraulic fracture surface area that is created. In order to achieve optimum horizontal well stimulation, the lateral section must be characterized and the perforation placement customized to account for reservoir changes along the wellbore. In most cases evaluation is limited to a gamma ray measurement while-drilling (MWD) tool and, periodically, mud log. While these tools can identify significant structural changes and hydrocarbon shows along the lateral, they provide little stratigraphic information, no natural fracture information, and no stress information. One log evaluation tool that is being used more frequently in horizontal wells is the formation imager. It produces electrical images of the borehole that provide detailed structural information such as faulting and natural fracturing. The images can also be used to estimate the stress state along the lateral via the presence and orientation, or absence, of drilling induced fractures. With this information important completion decisions can be made such as: lateral isolation need, stimulation staging requirements, perforation cluster design and spacing. Images can also identify offset well hydraulic fractures when they are intersected. This too can drive perforating and completion strategies, as well as future infill well placement. This paper describes how formation images have been used to implement changes to the completion process in horizontal Barnett shale wells. Stimulation staging and perforation placement strategies now utilize this information. In addition, actual stimulation pressure responses and microseismic activity are compared to those predicted from image logs. Infill drilling strategies, taking into account the location of offset hydraulic fractures, are reviewed as well.