Optimization of Water Avoidance Height in Horizontal Wells in Carbonate Bottom Water Gas Reservoirs

Abstract

Abstract Water production in gas wells is extremely harmful to the development of gas reservoirs, which is mainly reflected in the fact that once the energy of gas reservoirs is insufficient, gas cannot completely carry the produced water out of wellbore, resulting in fluid accumulation in wellbore. Fluid accumulation in wellbore will increase backpressure on gas layer and limit well productivity. The fluid column in wellbore will damage formations near the wellbore, increase formation water saturation, reduce gas phase permeability and well productivity. The invasion of formation water into subtle gas reservoirs will reduce recoverable reserves. In addition, water production from gas wells will reduce the quality of natural gas, for which dehydration equipment and additional costs are needed, thereby increasing production costs and reducing economic benefits. The development of bottom water gas reservoirs occupies an important position in gas reservoir development. For horizontally distributed bottom water gas reservoirs, compared with vertical wells, horizontal wells can reduce drawdown pressure, slow down water breakthrough in gas wells, and enhance the recovery factor of gas fields at the same gas production rate. Therefore, for gas reservoirs with bottom water, avoiding bottom water coning and slowing down water breakthrough in gas fields are the focus problems throughout the development process.Taking the gas field in the Amu Darya Right Bank Area in Turkmenistan as an example, this paper systematically studies the optimization of the water avoidance height in horizontal wells in bottom water gas reservoirs and the influence of bottom water invasion on the development effect of gas reservoirs during the development of horizontal wells in carbonate gas reservoirs, and then analyzes the relationship between the position of different horizontal sections and the ultimate recovery factor of gas reservoirs. Finally, the well pattern deployment and well trajectory design indicators for gas reservoirs is optimized, thereby extending the water-free gas production period of bottom water gas reservoirs and enhancing the recovery factor of the gas field.KeywordsBottom water gas reservoirHorizontal wellWater avoidance heightWater breakthrough time