开采区块地表沉降位移的有限元分析

Finite element analysis of surface subsidence displacement in recovery blocks

地下水和油气过度开采引起RQ区块地表沉降,致使套管上窜位移达1.15m,选取该区块中地表面积2220m×1560m,垂深3300m作为研究对象,考虑12口油井、3个水层、1个油层和2个夹层,建立了空间地应力与地位移计算模型;通过对3种工况下均匀储层的有限元分析计算,得到了开采后不同孔隙流体压力作用下各储层的变形和地表沉降位移,其中底层水引起地表沉降位移最大,占总位移的42.9%;根据12口井套管上窜位移实测值,采用反分析技术,探讨了RQ区块储层不均匀孔隙流体压力对地表沉降不均匀位移的影响,在套管上窜位移比较大的井周围,其孔隙压力比较低,为进一步预测和控制RQ区块地表沉降位移提供依据.

Excessive recovery of groundwater and oil gas are causing earth's surface subsidence on the RQ blocks, it causes casing pipes to move up, its displacement is up to 1.15 m. In the paper, research objective is selected in this block, the earth's surface area is 2 220 m by 1 560 m, the depth is 3 300 m. Computation model of dimensional ground stress and ground displacement is established considering 12 oil wells, 3 water layers, 1 oil layer and 2 interlayers. Through finite element analysis computation of uniform layer in the 3 cases, we derived each layer's deformation and surface subsidence displacement under different pore fluid pressures after exploitation Results show that surface subsidence displacement caused by first floor water is the biggest, covering 42.9% of total displacement. Meanwhile according to the casing pipe displacement's survey value of 12 wells, we use the anti-parsing technique to study effect of surface subsidence uneven displacement caused by uneven pore pressure in RQ block, among wells the casing pipe displacement of which is fairly bigger, its pore pressure is fairly lower. It will provide basis for further calculating and controlling surface subsidence displacement in RQ block.