Analysis of post-audits for Gulf of Mexico gravel-packed oilwell completions leads to continuous improvement in completion practices

Final production rate alone is not an adequate measure of the success of a well completion. Rather, we must estimate the "potential" of a reservoir an d judge the ultimate success of a completion on how close we come to achiev ing this potential. Specific productivity indexes (SPI's) [(BFPD/ft)/psi], specific injectivity indexes (SII's) [(BFPD/ft)/psi], and completion effici encies (CE's) (percent of Darcy radial flow) can be calculated at various t imes throughout a well completion. Analysis of these data quantifies the ef ficiency of the completion after each individual completion operation, allo wing a determination of the effects of each completion practice to be made. In addition to completion efficiency data, a comparison of gravel placemen t volumes behind casing helps quantify optimum gravel packing procedures. Twenty-two Gulf of Mexico completions have been analyzed using this techniq ue. In this paper we will give details of the results of this analysis, in particular the productivity effects of various methods of underbalanced per forating, gravel packing, and well control. Items of discussion include the effects of underbalanced perforating on well performance, the effects of f lowback after perforating on perforation tunnel cleaning, productivity impa cts of various types of well control methods following perforating and grav el packing, and comparisons of gravel pack design parameters and gravel pla cement behind casing.