When an operator is planning to drill a horizontal completion in a lower-permeability carbonate or sandstone reservoir, one of the prime well-design considerations is cost containment. Unfortunately, many operators use decision-making processes that are inappropriately weighted toward cost reduction and insufficiently or incompletely weighted toward incorporating completion processes that will ensure adequate producing rates. As a result, the ultimate hydrocarbon recoveries that were used in the economic justification of the program may not be achieved.
This paper presents a case study of a multiyear horizontal completion project in west Texas that was very successful in exposing the "false economy" of not cementing casing in horizontal wells drilled in low-permeability reservoirs. Increasing initial well costs about 20 to 25% resulted in a 3- to 10-fold increase in economic returns. This project included wells drilled in the heart of the play, in one of the flank areas, and also in an "edge" portion of the field, with comparisons to openhole completions in each area. The project offers several guidelines that should be followed by almost any global application of horizontal completions in lower-permeability reservoirs.