井地电阻率法歧离率确定高阻油气藏边界

Determination of borders for resistive oil and gas reservoirs by deviation rate using the hole-to-surface resistivity method

根据油气藏的特征,抽象出地球物理模型,利用有限元软件FEPG对三维油气藏模型的稳恒电流场进行了数值模拟.根据井地电阻率法计算结果,定义了一种新的参数歧离率,分析了不同深度油气藏和油气藏偏离钻井位置时歧离率的变化规律,并利用该参数及其梯度确定油气藏边界范围.理论分析表明,参数歧离率可很好地突出油气藏异常并确定其横向边界范围.

According to characteristics of oil and gas reservoirs, the geophysical model is abstracted, and the 3-D steady current field of oil and gas reservoirs is simulated by the finite element software FEPG. Based on calculated results by the hole-to-surface resistivity method, a new parameter of the deviation rate is defined, and the law of deviation rate for oil and gas reservoirs of different depths deviated from the borehole is analyzed. Thus the range of the border for oil and gas reservoirs can be located through the parameter of the deviation rate and its gradient. Theoretic analysis indicates that abnormity of oil and gas reservoirs can be well stood out by the parameter of the deviation rate and the transverse border can be determined, and this is a practical and efficient method.