Understanding mechanical rock properties is essential for optimal well placement and hydraulic stimulation design which directly impacts hydrocarbon productivity from shale reservoirs with ultra-low permeability. Current industrial practice is to assess spatial variability of subsurface mechanical properties through analyzing core and dipole sonic logs. Seismic inversion is another commonly applicable approach. However, although numerous existing approaches have contributed to upstream operators mitigating operational risk, these individual or combined evaluations ultimately require significant cost and time for exploration. These approaches also have limitations identifying fine-scale variability within inter-well spacing or along the length of a horizontal well due to sparse pilot-well control and the intrinsic limitation of seismic resolution. In this study, we propose a new approach to capture spatial variability of Young’s modulus utilizing MWD (Measurement While Drilling) gamma ray logs of horizontal wells. The MWD gamma ray log is essentially acquired for the purpose of having geometric and stratigraphic information on well position while drilling in real time. And, due to cost and time related issues, shale operators commonly acquire only MWD log rather than core or wireline log set for horizontal production drilling while the massive pad drilling has the advantage of large areal coverage. Under the circumstance, MWD gamma ray log is often only data having geological implication. In purpose of utilizing MWD gamma ray log for geomechanical approaches, we examined a relationship between gamma ray and Young’s modulus acquired from pilot wells. The MWD gamma ray logs were converted into Young’s modulus logs and ultimately populated for three-dimensional property modeling. To validate the property model, an integrated assessment using wireline logs, microseismic, and three-dimensional seismic data was conducted. The study results demonstrate that this new geomechanical approach utilizing MWD gamma ray logs can be supportive or even serve as an alternative to the existing approaches. The method enables identification of finer-scale spatial variability than sparse pilot-well control and conventional seismic analysis, which is attributed to the advantage of long-lateral, multi-benched, staggered, and dense production well placement. Based on the reliability and cost-effectiveness of the new approach, we expect it could help upstream operators mitigate risk and uncertainty related to geomechanical properties without excessive spending for exploration and ultimately improve hydrocarbon productivity with optimal well completion strategies.

了解机械岩石特性对于优化井位和水力增产设计至关重要，这会直接影响具有超低渗透率的页岩油藏的油气产量。当前的工业实践是通过分析岩心和偶极声波测井资料来评估地下力学性质的空间变异性。地震反演是另一种普遍适用的方法。但是，尽管许多现有方法已有助于上游运营商降低运营风险，但这些单独或组合的评估最终需要大量的勘探成本和时间。这些方法也存在局限性，因为稀疏的先导井控制和地震分辨率的固有局限性使得无法识别井间间距内或沿水平井长度的精细尺度变化。在这项研究中，我们提出了一种利用水平井MWD（随钻测量）伽马射线测井曲线记录杨氏模量空间变异性的新方法。MWD伽马射线测井仪基本上是为了在实时钻探时获得有关井眼位置的几何和地层信息的目的而获得的。并且，由于与成本和时间有关的问题，页岩作业者通常仅获取随钻测井测井数据，而不获取岩心或电缆测井数据集进行水平生产钻探，而大规模的垫层钻探具有覆盖面积大的优势。在这种情况下，MWD伽马射线测井通常仅是具有地质意义的数据。为了利用随钻测井伽马射线测井仪进行地质力学方法，我们研究了伽马射线与从中试井获得的杨氏模量之间的关系。将MWD伽马射线测井仪转换为杨氏模量测井，并最终进行填充以进行三维特性建模。为了验证属性模型，使用了电缆测井，微地震和三维地震数据进行了综合评估。研究结果表明，这种利用MWD伽马射线测井仪的新地质力学方法可以提供支持，甚至可以替代现有方法。与稀疏的先导井控制和常规地震分析相比，该方法能够识别更精细的空间变化，这归因于长边，多弯，交错和密集的生产井布置的优势。根据新方法的可靠性和成本效益，