利用已钻井资料构建区域地层压力剖面的方法

地层压力是油气钻探和开发过程中钻井工程设计与施工的基础数据。针对新探区地层压力预测问题,提出地层压力矩阵的概念,在有效应力理论和Eaton方法计算地层孔隙压力的基础上,给出地层孔隙压力矩阵的构建方法,通过地层压力矩阵可以得到地层压力曲线或含不确定信息的地层压力剖面。在地层压力矩阵的基础上,利用深度平差方法和反距离加权算法,建立计算同构造区域内待钻井地层压力的外延移植算法。某构造区域内的井筒资料计算表明:由该方法得到的待钻井地层孔隙压力值与该井完井后利用测井资料计算的压力值最大相对误差为3.43%;邻井地层压力资料、邻井空间位置和目标区域空间连续性是影响地层压力外延移植方法计算精度的关键因素;对于存在断层或者地质构造比较复杂的地区,需要充分掌握地质构造特性并借助地震资料分构造、分区块建立目标井的地层压力。

A new method for establishing regional formation pressure profile based on drilled wells data

Formation pressure is the basic data needed in drilling engineering design and operation during the exploration and development of oil and gas fields. To improve the prediction of formation pressure in a new exploration region, a method for the construction of formation pressure matrix was proposed, which was based on the effective stress theory and Eaton method. The formation pressure profile or the pressure along the wellbore with some uncertainties can be calculated according to the formation pressure matrix. A transplantation method calculating the formation pressure of the targeted wells in the region was given combining with depth adjustment and arithmetically modified distance weighting methods. Case studies were carried out to verify the method, in which the predicted formation pressure was compared with that derived from the well logging. The results show that the maximum relative errors are within 3.43%. The accuracy of the transplantation method is affected by the pressure data of the drilled wells nearby and their locations, and the spatial continuity of the formation in the targeted region. For a region with complicated geological structures, its geological characteristics need to be fully understood and analyzed, and care should be taken in using the formation pressure matrix and the transplantation method for the prediction of the formation pressure of targeted wells.