Stand-alone-screen candidate selection methodology




Christine, Chichi Ola

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An operator has some deepwater horizontal oil producing wells with stand-alone-screens (SAS) or unintentional SAS (incomplete open hole gravel packs). The objective of this project is to review sand control and production in these wells; to assess selection criteria for SAS; review factors that influence SAS performance such as bean up, fluids and contingency planning; and to provide recommendations with respect to SAS criteria. This project could save $ 6 - 8 million per well for the deepwater operator. SAS offers reduced cost, skin, complexity and logistics, which are necessary to make some well projects economical. The risk in deepwater subsea operations is an earlier workover costing about $39.2 million. In the past, this has made some operators recommend SAS for land and shallow offshore only. However, there are deepwater wells where open hole gravel packs are not preferred such as low cost wells, wells with unstable formations that bridge off the hole quickly, wells with narrow pore pressure-fracture pressure windows, high pressure/high temperature wells with fluid compatibility issues, tortuous wells seeking multiple targets, extended reach wells, etc. More recently, some operators are now using SAS for carefully selected non-traditional SAS candidates based on tests and other important factors. At the end of the study of the operator’s wells, it was concluded that six out of seven wells with SAS were successful because they had zero to minimal sand production and good oil flow as expected. This is an 85% success rate. The operator had more conservative selection criteria for SAS than the wells parameters. Shales were isolated with blank pipes in the wells. Well surveillance will be continued to see how the wells perform over the years. The operator was advised to adjust their selection criteria by a moderate percentage, as long as the SAS to be used is physically tested with a laboratory model to validate use of the SAS in such wells.



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