Horizontal wells dominate the development of unconventional shale reservoirs. Using real time drilling data to steer in a target zone is the key to economic success. Today structural interpretation in unconventional horizontal wells is a manual process that is time-consuming, tedious, and error-prone, especially because gamma-ray (GR) logs are commonly the only available logging-while-drilling data. For the first time, a method named TST3D is developed to automate interpretation of subsurface structure. TST3D (true stratigraphic thickness in three-dimensional space) automates structural interpretation using pattern recognition. Given an initial structural model, TST3D automatically computes true stratigraphic thickness (TST) as the shortest distance from each wellbore survey location to the initial surface, then matches GR patterns in the horizontal well to those seen in a vertical pilot well in TST domain. TST3D inserts fold hinges, bends the structure, then recomputes the modeled GR response, progressively matching the pilot well log signature, from heel to toe in the horizontal well. There are three assumptions in the current version of TST3D: constant layer thickness across the drilled interval, GR variation follows stratigraphic layering, and no faults are present in the drilled section. Those assumptions are reasonable in most shale plays. The TST3D method can be applied in either a post-drill mode for structural interpretation or real-time mode for aiding geosteering. Field tests in different shale plays and complex well trajectories demonstrate that TST3D runs quickly: a structural model of a 10,000-ft horizontal section can be computed in minutes, and a real-time update of 100 ft of new data takes less than a minute. Automating the geosteering correlation process would allow well placement engineers to cover multiple wells simultaneously, increasing the efficiency of the team while potentially improving service quality.

水平井主导着非常规页岩油藏的开发。使用实时钻探数据引导目标区域是经济成功的关键。如今，非常规水平井的结构解释是一种手动过程，该过程耗时，繁琐且容易出错，特别是因为伽马射线（GR）测井通常是唯一的随钻测井数据。首次开发了一种名为TST3D的方法来自动解释地下结构。TST3D（三维空间中的真实地层厚度）使用模式识别自动进行结构解释。给定初始结构模型，TST3D会自动计算真实地层厚度（TST），即从每个井眼测量位置到初始表面的最短距离，然后将水平井中的GR模式与TST域中垂直井中的GR模式进行匹配。TST3D插入折叠铰链，弯曲结构，然后重新计算建模的GR响应，从水平井的脚跟到脚趾逐渐匹配试井测井特征。当前版本的TST3D中有三个假设：整个钻探层段的层厚度恒定，地层分层后GR的变化以及在钻探段中没有断层。这些假设在大多数页岩油藏中都是合理的。TST3D方法既可以应用于构造后解释的钻后模式，也可以应用于辅助地质导向的实时模式。在不同的页岩气层和复杂的井眼轨迹中进行的现场测试表明，TST3D运行迅速：一个结构模型为10，可以在数分钟内计算出000英尺的水平截面，并且实时更新100英尺的新数据所需的时间不到一分钟。使地质导向关联过程自动化将使油井布置工程师可以同时覆盖多口油井，从而提高了团队的效率，同时有可能改善服务质量。