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Novel Model for Rate Transient Analysis in Stress-Sensitive Shale Gas Reservoirs
ACS Omega ( IF 3.7 ) Pub Date : 2021-05-27 , DOI: 10.1021/acsomega.1c00259 Ting Lu 1 , Shengxiang Long 1 , Zhiping Li 2 , Shimin Liu 3 , Yu Liu 4 , Caspar Daniel Adenutsi 5 , Zeyang Peng 1
ACS Omega ( IF 3.7 ) Pub Date : 2021-05-27 , DOI: 10.1021/acsomega.1c00259 Ting Lu 1 , Shengxiang Long 1 , Zhiping Li 2 , Shimin Liu 3 , Yu Liu 4 , Caspar Daniel Adenutsi 5 , Zeyang Peng 1
Affiliation
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Technical advances in hydraulic fracturing and horizontal drilling technologies enable shale to be commercially exploited. Due to the technical and economic limitations of well testing in shale gas plays, rate transient analysis has become a more attractive option. After hydraulic fracturing, flow mechanisms in multiple scaled pores of shale become extraordinarily complicated: adsorption in nanopores, diffusion in micropores, and non-Darcy flow in macropores. Moreover, shale gas reservoirs are stress-sensitive because of ultralow permeability and diffusivity in a matrix. Furthermore, the porosity and permeability of natural fractures are stress-dependent as well. Accounting for all of these complex flow mechanisms, especially the aforementioned stress-sensitive parameters, a semianalytical production solution of a multiple fractured horizontal well (MFHW) can rapidly predict the entire production behavior. Scholars have done much work on the complex flow mechanisms of shale. Most models regarded permeability as a stress-sensitive parameter while diffusivity and porosity were considered to be a constant. However, diffusivity and porosity were proved to be stress-sensitive as experimental science developed. In this study, we present a novel semianalytical model for rate transient analysis of MFHW, which simultaneously incorporates multiple stress-sensitive parameters into flow mechanisms. Substituting stress-dependent parameters (diffusivity, porosity, and permeability) into governing equations resulted in strong nonlinearities, which was solved by employing the perturbation method. Production behaviors with only stress-sensitive permeability were compared with multiple stress-dependent parameters. The new model with multiple stress-sensitive parameters declined slower than the permeability-sensitive model, and the new model matched better with the field data. In addition, the effects of major stress-sensitive parameters on production decline curves were analyzed by the proposed model. The sensitivity analysis indicated that different parameters had their own degree of sensitivity intensity and influence on the production period. Finally, 1001 wells from the Marcellus shale play were divided into three well groups. Estimated inversion values of reservoir parameters from the three well groups and relevant single wells were consistent with the field data. The inverted values of single wells fluctuate within the inversion values of well groups, which indicates that the production behavior of well groups could be a guide for rate transient analysis of a single well in shale gas reservoirs.
中文翻译：
页岩气储层速率瞬态分析新模型
水力压裂和水平钻井技术的进步使页岩能够进行商业开发。由于页岩气区试井的技术和经济限制，速率瞬态分析已成为更具吸引力的选择。水力压裂后，页岩多尺度孔隙的流动机制变得异常复杂：纳米孔吸附、微孔扩散、大孔非达西流动。此外，由于基质中的超低渗透率和扩散率，页岩气储层对应力敏感。此外，天然裂缝的孔隙度和渗透率也与应力有关。考虑到所有这些复杂的流动机制，尤其是上述应力敏感参数，多压裂水平井 (MFHW) 的半分析生产解决方案可以快速预测整个生产行为。学者们在页岩复杂的流动机制方面做了大量工作。大多数模型将渗透率视为应力敏感参数，而扩散率和孔隙率被视为常数。然而，随着实验科学的发展，扩散率和孔隙率被证明是应力敏感的。在这项研究中，我们提出了一种新的半解析模型，用于 MFHW 的速率瞬态分析，该模型同时将多个应力敏感参数纳入流动机制。将与应力相关的参数（扩散率、孔隙率和渗透率）代入控制方程会产生很强的非线性，这可以通过使用微扰方法解决。将仅具有应力敏感渗透率的生产行为与多个应力相关参数进行了比较。具有多个应力敏感参数的新模型比渗透率敏感模型下降得更慢，并且新模型与现场数据更好地匹配。此外，该模型还分析了主要应力敏感参数对产量递减曲线的影响。敏感性分析表明，不同参数的敏感性强度不同，对生产周期的影响也不同。最后，将 Marcellus 页岩区的 1001 口井分为三个井组。三个井组及相关单井储层参数反演估计值与现场数据一致。
更新日期：2021-06-08
中文翻译：
页岩气储层速率瞬态分析新模型
水力压裂和水平钻井技术的进步使页岩能够进行商业开发。由于页岩气区试井的技术和经济限制，速率瞬态分析已成为更具吸引力的选择。水力压裂后，页岩多尺度孔隙的流动机制变得异常复杂：纳米孔吸附、微孔扩散、大孔非达西流动。此外，由于基质中的超低渗透率和扩散率，页岩气储层对应力敏感。此外，天然裂缝的孔隙度和渗透率也与应力有关。考虑到所有这些复杂的流动机制，尤其是上述应力敏感参数，多压裂水平井 (MFHW) 的半分析生产解决方案可以快速预测整个生产行为。学者们在页岩复杂的流动机制方面做了大量工作。大多数模型将渗透率视为应力敏感参数，而扩散率和孔隙率被视为常数。然而，随着实验科学的发展，扩散率和孔隙率被证明是应力敏感的。在这项研究中，我们提出了一种新的半解析模型，用于 MFHW 的速率瞬态分析，该模型同时将多个应力敏感参数纳入流动机制。将与应力相关的参数（扩散率、孔隙率和渗透率）代入控制方程会产生很强的非线性，这可以通过使用微扰方法解决。将仅具有应力敏感渗透率的生产行为与多个应力相关参数进行了比较。具有多个应力敏感参数的新模型比渗透率敏感模型下降得更慢，并且新模型与现场数据更好地匹配。此外，该模型还分析了主要应力敏感参数对产量递减曲线的影响。敏感性分析表明，不同参数的敏感性强度不同，对生产周期的影响也不同。最后，将 Marcellus 页岩区的 1001 口井分为三个井组。三个井组及相关单井储层参数反演估计值与现场数据一致。
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