Evolution of cementing and stimulation techniques for horizontal wells drilled in unconventional shale formations

Drilling and completion of unconventional shale formation is one of the fastest growing technologies in tight shale formation. The number of wells drilled in search of gas in shale is increasing rapidly since the beginning of 2000. Cementing these wells poses several challenges. The productive zone throughout the play has been developed using a combination of vertical and horizontal wells. Production from the reservoirs has been optimized by using various completion and stimulation techniques. Currently in an effort to reduce environmental impact, increase the net present value, and maximize reservoir pressure and contact into the thin sweet spots, horizontal wells have gained popularity in these shale formations. The performance of these reservoirs depends upon the completion and stimulation methods used because the matrix permeability is too low for commercial production of gas. The wellbore area must be increased in order to reach the immobile hydrocarbons. The techniques and materials used for fracturing these wells and enhance the effective wellbore drainage radius are numerous. Previous experience from these formations showed some enhancement for vertical wells completed with hydraulic fracturing. The early stimulation techniques were primarily nitrogen-foam fracture treatments which yielded economic rates necessary for further filed development of these formations. Better enhancement is expected from the same formations if horizontal wells are drilled coupled with multistage hydraulic fracturing. This enhancement can further be improved by stimulating with slick water and cross-linked gels. This paper will discuss the challenges during cementing and stimulation of horizontal well. Finally, materials that are most economically viable in these formations will be enumerated.