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In general, the use of standalone screen (SAS) completion has significant economic (cost saving) and productivity (skin) advantages compared to the conventional open hole gravel pack (OHGP) completion. However, SAS completion, especially in horizontal gas well with high potential of sanding typically suffers from premature failure due to sand erosion caused by high annular velocity near the heel section. This paper describes the work conducted to understand in detail and quantify the erosion risks on SAS in horizontal gas well and the proof-of-concept assessment of using swelling elastomer packers to segmentize the flow in the annulus as a mean to reduce erosion risks near the heel. The work involves carefully designed and selected experimental and Computational Fluid Dynamics (CFD) simulation work programs that focused on development of erosion model at room and elevated temperature, understanding and validation of sand screen failure using the developed erosion model, and CFD simulation and validation of gas flow profile in basepipe and annulus sections to understand the effect of flow segmentizers in reducing annulus velocity. From this work, an improved sand erosion model was developed based on the Cylinder-In-Pipe methodology for the sand screen materials and downhole sand Particle Size Distribution (PSD) combinations at room and elevated temperature. Conditions that led to the failure of sand screen filter due to erosion damage were also established through the Sample-In-Pipe experiments. Validation of erosion on one-metre length of screen shows that CFD, combined with sound experimental techniques, can provide accurate prediction of sand screen material metal loss due to sand impact. CFD simulation of gas flow in horizontal gas well completion were conducted in order to provide further insights and confidence in using flow segmentizers to control annular velocity. Finally, a pilot application of the concept in a gas field in Malaysia, based on integration of all the findings will be presented together with comparison to a similar well within the same field but completed with OHGP completion showing that the SAS with flow segmentizers concept has led to significant CAPEX savings and high well productivity. |
