Water/Gas Shut-off Candidates Selection

Abstract

Selecting water/gas shut-off (WGSO) candidates with proper understanding is a critical step which influences outcome of any WGSO effort. Quite often an inexperienced engineer is perplexed by the task of having to find candidates for water/gas shut-off applications, whereas he/she has little idea as to where to start. He/she gets even more confused by selection criteria suggested by various authors, which aren't very clear.In this paper a systematic approach for finding suitable candidates for WGSO applications is presented. Several techniques of WGSO candidate pre-screening are discussed. A step by step procedure which takes the engineer through a clear thinking process is suggested. WGSO candidates selection is best treated as part of his/her routine wellbore utility study (yearly event). Starting point is to conduct a well and reservoir performance review for the entire field based on all the data in hand. A list of required basic data which are helpful in this review is provided, as much of which as possible should be collated prior to this candidate selection exercise. Guidelines for further diagnosis to firm up WGSO candidates is also provided. Outcome of this study is a comprehensive list of all potential remedial work, of which WGSO is a subset. Having a complete picture of the well and reservoir performance helps an engineer understand reservoir fluid movement mechanism and therefore objectives of any remedial work becomes very clear. Then the engineer can review all products and services available in the market and can choose the most appropriate solution. Without a proper diagnosis and clear understanding of reservoir fluid flow pattern, any attempted solution will only be a guesswork and success rate will remain low.