超压泥岩盖层中断裂垂向封闭性的定量评价

Quantitative evaluation for vertical sealing ability of faults in
overpressure mudstone cap rock

付 广 张 楠

大庆石油学院地球科学学院，黑龙江 大庆 163318

College of Geoscience, Daqing Petroleum Institute, Daqing 163318,China

超压泥岩盖层内断裂能否形成垂向封闭，关键取决于其断裂带内泥岩盖层岩石排替压力的大小，排替压力越大，封闭能力越强；反之则越弱。根据不被破坏泥岩盖层与断层带内泥岩盖层岩石排替压力之间的关系，利用超压使断裂带内泥岩盖层排替压力的改变系数，建立了一套超压泥岩盖层内断裂垂向封闭能力的评价方法，并将其应用于海拉尔盆地乌尔逊凹陷苏仁诺尔断裂在大一段超压泥岩盖层内断裂垂向封闭性评价中，结果得到其均具有较好的封闭能力，较大一段泥岩盖层封闭能力还强，与目前该凹陷南二段油气分布十分吻合，表明该方法用于超压泥岩盖层内断裂垂向封闭性评价是可行的。

Whether faults in overpressure mudstone cap rock can form vertical sealing crucially depends on the size of rock displacement pressure of cap rock in fault zone. The greater displacement pressure is, the stronger sealing ability will be, and conversely the lower. According to the relation between displacement pressure of not destroyed mudstone cap rock and displacement pressure of mudstone cap in fault zone, by use of changing coefficient of overpressure to sealing ability of mudstone cap rock in fault zone, an evaluation method for vertical sealing ability of faults in overpressure mudstone cap rock was established, and it was applied in the evaluation for vertical sealing ability of Surennuoer Faults in K1d1 overpressure mudstone
cap rock of Wuerxun Depression in Hailaer Basin. It was concluded that sealing ability was well developed there and was greater than that of K1d1 mudstone cap rock. It was well consistent with the distribution of oil and gas in K1n2. All those facts show that this method is feasible for the evaluation of vertical sealing ability of faults in overpressure mudstone cap rock.