Validation of Geomechanical Sanding Predictions with Subsequent Production and Water Injection in a Rejuvenated Oil Field, Offshore Malaysia

Abstract

Abstract The "Z-field" is located in Offshore Malaysia and is a shallow water, mature oil field consisting of stacked sandstone reservoirs with interlayered shales. It has been on production since the mid-1980s. Early production wells had cased and perforated completions with sand screens and internal gravel packs. However, due to low productivity, the subsequent wells were completed cased and perforated without downhole sand control. This paper focuses on the credibility of the geomechanical sanding risk evaluation, initially conducted at early field life, and revisited during the field redevelopment stage for sand control and completion decision for high-angled oil producer infill and water injection wells. Field observations to date confirm the accuracy of the latest geomechanical sanding evaluations conducted in 2014 and support the decision to not use downhole sand control. This has resulted in millions of dollars in savings on well construction costs and increased revenue from higher well productivity compared to the earlier wells from the 1980s that were completed with sand screens and internal gravel packs. This study demonstrates the validity of geomechanical assessments conducted at the beginning of field redevelopment. These studies were verified with several years of production data. It is concluded that with robust geomechanical modelling and frequent updates, reliable sanding risk assessments can be provided to well engineers and asset managers for fit-for-purpose and timely sand management and completion decisions.