白云深水区地层破裂压力计算方法及应用  

Calculation method and application of formation fracture pressure in Baiyun deepwater area

作　　者：何雁兵 郑金云 张明 HE Yanbing;ZHENG Jinyun;ZHANG Ming(Shenzhen Branch of CNOOC(China)Ltd.,Shenzhen 518054,China)

机构地区：[1]中海石油(中国)有限公司深圳分公司,深圳518054

出　　处：《海洋地质前沿》2022年第5期41-50,共10页Marine Geology Frontiers

基　　金：中海石油(中国)有限公司勘探生产科研重大项目“珠江口盆地(东部)浅水区古近系油气成藏条件及勘探突破方向”(SCKY-2020-SZ-21)。

摘　　要：地层破裂压力不仅可以用于钻井设计,也可用于盖层封烃高度、流体底辟区古压力系数等重要参数的计算。本次研究分析整理了白云深水区38口探井的测井数据,构建了泥岩密度随埋深的变化趋势,明确了研究区正常压实泥岩密度随埋深表现出“三段式”(<800、800~1 200、>2 200 m)变化趋势,并拟合出静岩压力及泊松比随深度变化的动态公式。采取Eaton法建立了不同水深条件下的地层破裂压力图版,结果与实钻井地漏测试结果吻合较好。利用编制的破裂压力-深度图版,明确了浅埋藏区圈闭盖层最大封烃高度计算方法,证实深水、超深水区薄盖层依然具备封烃能力;结合油气成藏期次研究,明确了近白云凹陷中心位置B2钻井周边底劈区的最大古压力系数为1.69~1.713。综合分析推测在研究区孔隙压力达到上覆泥岩破裂压力值的90%附近时,超压体系产生裂缝,泥岩盖层受到破坏,油气漏失。Formation fracture pressure can be used not only for drilling design, but also for calculation of important parameters such as hydrocarbon sealing height of caprock and ancient pressure coefficient of fluid diapir area.In this study, the logging data of 38 exploration wells in Baiyun deep-water area are analyzed and sorted, the variation trend of mudstone density with buried depth is constructed, the variation trend of normal compacted mudstone density with buried depth is defined as "Three-stage"(< 800, 800-1 200, > 2 200 m), and the dynamic formula of static rock pressure and Poisson’s ratio with depth is fitted.The Eaton method is adopted to establish the chart of formation fracture pressure under different water depths, and the results are in good agreement with the leakage pressure obtained by actual drilling.Using the compiled fracture pressure-depth chart, the calculation method of the maximum hydrocarbon sealing height of the trap caprock in shallow buried area is clarified, and it is confirmed that the thin caprock in deep and ultra-deep water areas still has the hydrocarbon sealing ability.Combined with the study of oil and gas accumulation periods, it is clear that the maximum Paleopressure coefficient in the bottom splitting area around B2 well near the center of Baiyun sag is 1.69~1.713.Through comprehensive analysis, it is speculated that when the pore pressure in the study area reaches about 90% of the fracture pressure of the overlying mudstone, the overpressure system will produce cracks, the mudstone caprock will be damaged and oil and gas leakage will occur.

关 键 词：珠江口盆地 白云深水区 地层破裂压力 封烃高度计算 古压力系数 

分 类 号：P744.4[天文地球—海洋科学]