Evaluation of Cased-Hole Expandable Sand Screen (ESS) Application in Gas Wells.

Abstract

Sand face completions have a major impact on a well's deliverability, by determining its productivity or injectvity throughout its expected life. In the Niger Delta, most reservoirs are shallow (below 10,000 ftss) and poorly consolidated, sand control forms an important part of sand face completion design. Sand management strategy involves using a software FIST (Fully Integrated Sand Prediction Tool) to carry out sand failure prediction analysis. In cases where sand failure is imminent, a sand control selection guide is used to determine the optimal sand control method to be installed. The selection is benchmarked against the performance of existing sand controls designs in analogue wells the in the region. A number of sand control mechanisms have been successfully deployed in various completions across Niger Delta which includes Chemical Sand Consolidation, Gravel Packs (Internal/External), Slotted liners, Expandable Sand Screens (ESS), etc. The complexity of deployment varies widely from the most complex multiple IGP/EGP to slotted liners. In all, most of the methods have exhibited good sand control properties however, with varied productivity. The ESS has presented a good balance between ease of deployment, productivity and life cycle management of the well. A field in the greater Gbaran area of the Niger Delta is proposed to be developed by three gas wells targeting three reservoirs. The reservoirs are unconsolidated and below 10,000 ftss, with Sonic log transit times in the range of 93 - 162 μsec/ft. Sand failure prediction on these three reservoirs using FIST indicated a high failure probability (95 – 100%) during the production life, thus requiring sand control. Following the process of selection, and Cased-Hole ESS was proposed. Although cheaper and easier to install with better productivity, a proper evaluation of the erosion tendency especially in Cased-Hole application of ESS in gas wells is essential to ensure full life cycle coverage. This paper documents the results of the evaluations carried out, optimization methods employed to evaluate the proposed sand control mechanism.