准噶尔盆地西北缘九区火山岩储层裂缝预测

FRACTURE IDENTIFICATION IN IGNEOUS ROCK RESERVOIRS OF THE NINTH BLOCK AT THE NORTHWEST MARGIN OF THE JUNGGAR BASIN

为准确预测准噶尔盆地西北缘九区火山岩储层裂缝,以研究区断裂构造形迹为基础,利用数值模拟分析技术,模拟计算了该区石炭系火山岩储层的古构造应力场;然后根据火山岩的力学性质计算出岩体的破裂接近程度系数(η)及其分布;将η与实际资料对比,确定裂缝发育级别及其对应的η值;利用此标准,结合岩石力学与构造地质学理论、对照岩心裂缝观测结果,综合分析钻井、录井以及实际生产资料,对裂缝发育程度、裂缝类型及产状等进行了综合预测。结论如下:①研究区石炭系火山岩油气藏储层裂缝非常发育,几乎所有的火山岩中都不同程度地发育有裂缝;②裂缝延伸方位主要为北东—南西向,其次是北西—南东向;③裂缝在平面上的分布主要集中在断层附近,特别是断层的交汇部位。总体来看,研究区的裂缝发育分布特征比较有规律性。

In order to accurately identify fractures in the igneous rock reservoirs at the northwest margin of the Junggar basin, numerical simulation analysis technologies were used to calculate the palaeotectonic stress field of the Cretaceous igneous rock reservoirs in the study area based on the structural features of faults. Coefficient of fracture approximation degree (η) and distribution of rock matrix were determined according to the mechanical properties of the igneous rocks. The calculated η was correlated with the real data to determine the level of fracture development and their corresponding values of η. In combination with the theories of rock mechanics and structural geology and the results of core observation, these standards were used to comprehensively predict the level of fracture development, fracture types and occurrences through multidisciplinary analysis of drilling, logging and real production data. The following understandings were obtained: ① Fractures are highly developed in the Cretaceous igneous rock reservoirs and occur almost in all of the igneous rocks to a certain degree; ② The fractures are mainly of NE-SW trending fractures, followed by NW-SE trending fractures; ③ The fractures cluster around faults, especially at the convergences of faults. As a whole, the development and distribution of fractures in the study area show certain regularity.