Optimization of the Turnaround Time and Quality of Production-Screening Tests in Offshore Fields – Some Case Studies

Abstract

Production-screening test (PST) is performed on a reservoir drill-in fluid (RDIF) prior to running any component of the lower completion assembly that is vulnerable to plugging. This is applicable in open-hole completions in which wire-wrapped production screens are deployed. The key objective of a PST is to reduce the risk of plugging key completion components, such as production screens, during subsequent flow back. Hence, a PST increases the chance of preserving well productivity (or injectivity), ultimate recovery and project economics. However, conducting and achieving PST-quality RDIF in offshore fields can be cumbersome, time-consuming, and expensive, yet the quality is not guaranteed. This paper presents the formulation, implementation, and results of a simple strategy to reduce the turnaround time and costs of achieving PST-quality RDIF for applications in offshore fields. Employing a combination of on-the-job assessment, empirical data and expert opinions, the strengths and weaknesses of onsite versus offsite (onshore) options of preparing PST-quality RDIF for offshore operations are evaluated. As a case-study, empirical data from the execution of both onsite and offsite options for an example field are employed for the evaluation. Results of simple cost-time-benefit analysis underscore the robustness and competitiveness of preparing the PST-quality RDIF offsite and transporting same for subsequent test validation and application on the rig. The results of these empirical examples show that the offsite option yields about 75% cost-saving relative to its onsite counterpart. In addition to cost saving, other incremental benefits of the former include (i) significant reduction in rig time and personnel; (ii) improved RDIF quality; and (iii) higher chances of preserving well performance and economics. To increase the success rate, residual risks of the preferred offsite option are outlined, and relevant mitigations provided.