致密气藏水平井整体压裂井网部署优化

Optimization of integral fracturing design for horizontal well pattern arrangement in tight gas reservoir

致密气藏多采用衰竭式开发模式,如何减少井间干扰是井网部署时必须考虑的问题。针对目标研究区域,基于各压裂水平井的等效压力波及椭圆,建立了致密气藏水平并整体压裂井网部署优化模型。从弹性势能的角度,模拟目标区域和波及椭圆之间的运动,将井网部署模型转化为求取弹性势能函数的最小值问题,采用具有较高求解效率的拟物算法实现了该模型的求解。以M区块为例进行水平井整体压裂方案设计,模拟结果显示:气价较低时,M区块可采取稀井高产的开发模式;随着气价的增加,M区块需要打更多井以获得最佳的经济效益。

Depletion development is the main method to exploit tight gas reservoir, and well interference is the unavoidable factor in well network deployment. According to the target area, a new integral fracturing well pattern arrangement model for horizontal wells in tight gas reservoir was set up based on the non-overlapping pressure sweep ellipse areas of all fractured horizontal wells. Firstly, by solving the major semi-axis and minor semi-axis of the equivalent ellipses by commercial reservoir simulator, the move among the target area and equivalent ellipses was simulated from the view of elastic potential energy, and the well pattern arrangement model could be resolved as acquiring the minimum potential-energy function, which was solved by quasi-physical algorithm owing to the high solving efficiency. The method was applied in M block, which is a rectangle tight gas reservoir with an average porosity of 7.2% and an average permeability of 0.43×10-3 μm2. Economic evaluation demonstrated that less fractured horizontal wells could achieve more net benefit when the gas price is low, while more fractured horizontal wells should be developed when the gas price is high.