碳酸盐岩油藏缝洞单元离散数值模拟方法研究

摘要

由于碳酸盐岩油藏中的缝洞储集体分布具有极强的离散性和随机性，现有油藏数值模型不是十分适用。因此，首先以碳酸盐岩油藏溶洞和裂缝的地球物理识别预测结果和物性参数统计特征为主要依据，建立了规整化的离散缝洞分布模式；然后，通过引入裂缝连通流动系数、溶洞弹性储集系数建立了缝洞单元离散数值模拟方法；该模拟方法考虑了裂缝的各向异性和其中流体流动的非达西效应，以及溶洞中油水的重力分异效应，并利用T K472C单井缝洞单元和T K630多井缝洞单元生产历史数据对该模拟方法的可行性和可靠性进行了验证，结果表明，建立的缝洞型油藏离散数值模拟方法是可行和可靠的，可以用于碳酸盐岩油藏数值模拟；最后，基于历史拟合的T K472C单井缝洞单元和T K630多井缝洞单元地质模型，分析了注采参数对注水开发效果的影响。研究结果表明：强底水缝洞单元应依靠底水驱动方式进行开采，弱底水缝洞单元可以通过注入一定量的水来增加地层能量，在一定程度上抑制底水锥进；对于T K630多井缝洞单元，采出程度达到8％～10％时转注水和以3％的采液速度生产，注水开发效果较好。%Fracture‐cave units in the carbonate reservoir are seriously discrete and random in the distri‐bution ,so existing numerical simulation is not fit for the reservoir .A regular discrete fracture‐cave distribu‐tion mode was established according to geophysical recognition and prediction results of caves and fractures in the carbonate reservoir as well as statistical characteristics of physical parameters ;then ,a discrete nu‐merical simulation method was developed for the fracture‐cave unit based on fracture connection flow coef‐ficient and elastic accumulation coefficient of caves .It took account of fracture anisotropism ,non‐Darcy effect of fracture fluids and gravity differentiation effect of cave oil‐water .Feasibility and reliability of this simulation method were verified based on production history data of TK 472C single‐well fracture‐cave unit and TK630 multi‐well fracture‐cave unit .The results showed that ,the discrete numerical simulation meth‐od of fracture‐cave reservoir was feasible and reliable and could be used for numerical simulation of the car‐bonate reservoir .Finally ,effects of injection‐production parameters on water‐flooding development were an‐alyzed based on geological model of TK472C single‐well fracture‐cave unit and TK630 multi‐well fracture‐cave unit subject to history matching .The results showed that ,bottom water driving should be selected in the fracture‐cave reservoir with strong bottom water ;a certain amount of water could be injected into the fracture‐cave unit with weak bottom water to increase formation energy and control bottom water coning to some extent ;for TK630 multi‐well fracture‐cave unit ,water injection and fluid production rate of 3% could be taken when the recovery percentage was up to 8% 10% ,in order to reach the better water‐flooding development .