Optimized Design of Horizontal Well Sidetracking in a Porous Carbonate Reservoir with Thief Zone

Abstract

AbstractThief zone is a thin layer with high permeability and high permeability ratio to its adjacent reservoirs. Premature water breakthrough often occurs after the water injection in the reservoir with thief zone. When this kind of reservoir is developed by horizontal well, the stimulation measures are limited after the well pattern formed. Sidetracking is a practicable measure to develop the remaining oil with promised performance in the reservoir with thief zone. Its cost is lower than drilling new wells, and it can be directional drilling to the remaining oil rich zones. This paper takes a porous carbonate reservoir with thief zone in the Middle East as an example. Based on core data, well logging and production dynamic analysis, the existence of thief zone and the dominant injected water flow channel are clarified. Then the distribution of remaining oil is clearly depicted. Based on geological study, numerical simulation and drilling engineering, a sidetrack branched well plan for horizontal producers in reservoir with thief zone was carried out and eleven sidetrack branched well were designed. According to the simulation result, these wells will have an average cumulative oil increment of 0.75 MMB and an average well-controlled reserve recovery degree increment of 6.25%.KeywordsMiddle EastPorous carbonate reservoirThief zoneSidetrackingBranched well