区域性泥岩盖层阻止油气沿输导断裂运移机制及其判别方法

依据区域性泥岩盖层内断裂发育特征与油气沿断裂运移的关系和所需条件分析,对盖层阻止油气沿输导断裂运移机制进行研究,通过断接厚度与断裂上下不连接所需的相对最小断接厚度比较,建立一套区域性泥岩盖层阻止油气沿断裂运移的判别方法,并将其应用于南堡凹陷东二段相关研究中。结果表明:区域性泥岩盖层阻止油气沿输导断裂向上运移的机制是断裂在其内上下不连接,不能成为油气输导通道;形成条件是盖层断接厚度大于最小断接厚度;南堡凹陷东二段区域性泥岩盖层能够阻止下伏沙三段或沙一段源岩生成的天然气沿输导断裂向上运移的区域主要分布在凹陷西部,少量分布在凹陷东部局部地区,与目前的天然气分布相吻合,新方法可以用于判别区域性泥岩盖层能否阻止油气沿输导断裂运移。

Mechanism and detection of regional mudstone caprock sealing oil and gas migration along transporting fault

The mechanism and its detection of mudstone caprock sealing oil and gas migration along transporting fault were studied by analyzing the relation between the fault growth in regional mudstone caprock and oil and gas migration along transporting fault, and the required conditions. Through comparison of fault connecting thickness and the minimum thickness that upper and lower fault cannot connected,a detecting method of regional mudstone caprock sealing oil and gas migration along fault was determined,and was applied to the second member of Dongying Formation in Nanpu Depression. It is found that the condition of active regional mudstone caprock sealing oil and gas migration along fault is that the upper and lower fault cannot be connected, therefore allows a transporting passage of oil and gas. The formation requires that the caprock ''s fault connecting thickness is larger than the minimum faulting thickness. The area of caprock sealing oil and gas migration along transporting fault in the second member of Dongying Formation is mainly located in the west of Nanpu Depression and a small local area in the east, consistent with the distribution of found gas at present. The proposed method is available to detect whether regional mudstone caprock can seal oil and gas migration along transporting fault.