Abstract
Existing literature offers numerous success stories for stimulating cased/cemented horizontal completions in low-permeability reservoirs.1–8 However, operators who are faced with limited producing potential need to reduce well costs. Completing the horizontal section openhole or with a noncemented liner is attractive. In low-permeability reservoirs, production from such completions has often been below expectations, and sometimes even commercially unfeasible. This is especially true when we consider only completions in reservoirs other than fractured chalks.
To achieve proper stimulation with a technique such as fracture acidizing or hydraulic fracturing with proppants, operators must incorporate an economic and effective method for controlling the fluid or proppant placement. Currently, few well-proven technologies exist for controlling fracture placement in noncemented wellbores. In some cases, high risk or very high cost is associated with these technologies, depending on reservoir conditions or the potential for production improvement.
This paper examines several approaches that have been used to solve these problems, and presents some of the reasons for their mechanical and/or economical success or failure.
Generally, the successful use of either conventional fracturingtreatments or waterfracs (with very little or no proppant) will require some method of controlling fracture placement along the horizontal for significant production improvement. Controlling fracture placement is usually also required for effective fracture-acidizing of carbonate formations. Case histories from Canada and west Texas are included, and other examples within the literature are cited.
