This paper outlines a data collection and diagnostics case study involving multiple horizontal shale wells. We look at well production profiles using rate transient analysis, differences in near wellbore complexity, geologic variations within the area of interest, as well as compositional differences in the rocks based on cores obtained from within the stimulated reservoir. The Hydraulic Fracturing Test Site is a multi-well experiment involving stimulation of unconventional shale wells in the southeastern Midland portion of the Permian Basin. The targeted formations include both the upper as well as the middle Wolfcamp formations, also referred alternatively as Wolfcamp A and Wolfcamp B. Data integration and analysis shared in this paper help us understand the various geologic controls impacting well productivity, particularly the wide variance observed between the Wolfcamp A and Wolfcamp B formations. Rate transient analysis indicates similar system permeabilities for stimulated wells. However, we observe higher effective fracture half-lengths for upper Wolfcamp wells. Using observations from 3D seismic interpretations (such as pad scale faults) as well as petrophysical and image log data, we highlight the substantial differences in stimulation as we move along the well laterals from the heel toward the toe sections. These differences are further reconciled with observations from zones with high data density at the core locations through stimulated rock, as well as independent data such as microseismic emissions. At the test site, Wolfcamp A was found to be relatively quartz rich with significant heterogeneity whereas Wolfcamp B is richer in clay and organic content. This impacts the geomechanical characteristics of the rock mass with much higher natural fracture density in the shallower interval. Thus, the fracture growth is more uniform in the deeper interval and more heterogeneous with branching likely in upper interval. Increased complexity also leads to consistently better productivity from the wells in the shallower interval as demonstrated from RTA results. This case study is unique because it provides valuable insights from actual sampling of the stimulated zones in hydraulically fractured wells and helps understand impact of various factors that contribute toward variability in well production. The findings from this study provides insights into need for optimization of completion designs in the various Wolfcamp landing zones, such as optimization of cluster or fracture spacing in various Wolfcamp intervals. In addition, it provides a useful template for data collection and research direction in future field test sites of similar nature in unconventional reservoirs.

本文概述了涉及多个水平页岩井的数据收集和诊断案例研究。我们使用速率瞬态分析、近井眼复杂性的差异、感兴趣区域内的地质变化以及基于从增产储层内获得的岩心的岩石成分差异来查看井生产剖面。水力压裂试验场是一个多井实验，涉及对二叠纪盆地东南部米德兰部分的非常规页岩井进行增产。目标地层包括上部和中部 Wolfcamp 地层，也称为 Wolfcamp A 和 Wolfcamp B。 本文共享的数据集成和分析帮助我们了解影响井产能的各种地质​​控制，特别是在 Wolfcamp A 和 Wolfcamp B 地层之间观察到的巨大差异。速率瞬态分析表明增产井的系统渗透率相似。然而，我们观察到上 Wolfcamp 井的有效裂缝半长更高。使用来自 3D 地震解释（例如垫层断层）的观察结果以及岩石物理和图像测井数据，我们强调了当我们沿着井横向从跟部向趾部移动时增产的显着差异。这些差异与通过受激岩石在核心位置具有高数据密度的区域的观测结果以及微震发射等独立数据进一步协调。在测试现场，Wolfcamp A 的石英含量相对较高，具有显着的异质性，而 Wolfcamp B 的粘土和有机物含量更高。这会影响较浅层段具有更高天然裂缝密度的岩体的地质力学特性。因此，裂缝在较深的层段中生长更均匀，在上层段更可能分枝。正如 RTA 结果所证明的那样，复杂性的增加还导致较浅层段中井的生产率始终提高。这个案例研究是独一无二的，因为它从水力压裂井中增产区的实际采样中提供了宝贵的见解，并有助于了解导致井产量变化的各种因素的影响。这项研究的结果提供了对优化各个 Wolfcamp 着陆区完井设计的需求的见解，例如优化各个 Wolfcamp 间隔中的簇或裂缝间距。此外，它还为未来非常规油藏类似性质的现场试验场的数据收集和研究方向提供了有用的模板。