An Innovative Solution for Maximizing Productivity from Perforated Completions

Abstract Inadequate flow efficiency in perforated wells in cased-hole completions has been a major concern in the oilfield since the first use of perforating gun systems. Because of this, one of the primary needs in design of a perforated completion is the accurate assessment of the efficiency of the proposed perforation scenario to transmit fluid from the reservoir to the wellbore. Flow efficiency is affected by such conditions as the number of perforations actually open to flow, degree of damage around the perforations, formation physical properties, in-situ stress conditions influencing the perforator penetration, and extent of formation crushing around the perforation. This complex interaction of perforating geometry, formation characteristics, and perforating environment precludes traditional, global solutions to design or analyze perforated completions in order to achieve optimum productivity results. Each case must be addressed individually, and all possible information must be considered; (e.g., Cores, logs and well test results). Unfortunately, existing industry models used to design and optimize perforated completions are fairly basic and have relied primarily on section I API Perforator Test Data (i.e. perforator penetration and entrance-hole results obtained from testing the perforating system under surface conditions in concrete targets) for predicting downhole perforation performance. Since these models obviously do not reflect the actual reservoir conditions, field performance often falls short of predicted results because an accurate validation method for optimizing the gun selection process has not been applied. This paper will review a new quantitative method based on the unique properties of the reservoir that has been developed to optimize perforating design for individual wells. The process is based on experimental data from laboratory tests as well as theoretical (i.e. numerical and analytical) modeling to identify optimal parameters needed for efficiency in perforated completions. Case Histories showing the successful implementation of the quantitative method will be presented. The results attained from the process design technique will be validated against actual post-perforation, pressure-transient-analysis field data to demonstrate the productivity improvement that is possible through the use of this perforating solution.