Evaluating Completion Damage in High-Rate, Gravel-Packed Wells

Abstract

Summary Conoco recently completed and tested a series of high-rate, gravel-packed oil wells. Analysis of the well test data for the first completion indicated that significant formation/completion damage had been caused during the gravel-packing process. Extensive laboratory testing designed to closely simulate the completion procedure was performed in conjunction with detailed completion pressure loss evaluation. The studies identified the loss control material (LCM) pill used during completion operations as the primary source of damage. A new, self-breaking, LCM composition was designed that provided fluid-loss control with minimum formation/completion damage. This LCM system and a number of other design improvements were used in the field's remaining gravel-packed completions. We describe the analysis of well test data and the application of this information to evaluate completion procedures for these high-rate, cased-hole, gravel-packed completions. The analytical technique used is unique in that it combines laboratory, analytical, and operational data to quantify individual components of the total measured pressure drop across the completion. This approach provides significantly better insight into completion performance than merely stating an overall completion pressure drop, skin value, or well flow efficiency. The result of this systematic analysis of pressure losses is a better understanding of formation damage effects and the factors that influence them during the completion process. This in turn allows completion procedures to be modified to target specific areas for improvement.