In previous publications we have introduced methods for the matrix stimulation of horizontal wells, damage characterization and removal, and economic criteria for the evaluation of the job effectiveness. The characteristic shape of damage, which is neither radial nor evenly distributed along a horizontal well, would impact the effectiveness of a matrix stimulation treatment. Full removal of damage is probably never practical because of thief zones and a marked inability to divert the stimulation fluids. Also, the large volume of acid to be injected in horizontal wells will likely create significant corrosion problems. Therefore, partial stimulation and perhaps partial completion, by deliberately leaving segments of the horizontal well unperforated, should be contem-plated. By balancing the expected well performance against the fluid volumetric coverage and the length of the open segments, the optimum stimulation and completion design can be evaluated. The net present value (NPV) is used as the optimization criterion.
In this paper a case study of a 1600-ft horizontal well in a 160-acre drainage area in a sandstone reservoir is presented. Based on expressions for original and posttreatment skin effects, which are presented in explicit form, an economic evaluation of several stimulation and completion design options is carried out. A general recommendation on the proper matrix stimulation in horizontal wells is derived based on the results of this case study.