Yin Fuguo, Cheng Shiqing, Bai Wenpeng, Wang Yang, Liu Xiuwei
State Key Laboratory of Petroleum Resources and Engineering, China University of Petroleum Beijing, Beijing 102249, China.
ACS Omega. 2024 Apr 1;9(15):17307-17322. doi: 10.1021/acsomega.3c10360. eCollection 2024 Apr 16.
Fractured gas condensate reservoirs (FGCR) are a complex, special, and highly valuable type of gas reservoir, accounting for a significant proportion of gas reservoir development. In recent years, with the continuous advancement of horizontal well technology, it has become the main approach for the development of FGCR. The current model is unable to accurately represent the fluid distribution in the near-well area of horizontal wells due to the unique retrograde condensation phenomenon in GCR. Additionally, the presence of fractures complicates the solution of traditional analytical models. In response to this issue, this paper proposes a novel semianalytical model for horizontal wells in FGCR, which incorporates natural fractures, multiphase flow, and the influence of stress sensitivity on pressure response. A dual-porosity model is employed to simulate fractured reservoirs, and a four-region radial composite model is developed to characterize multiphase flow resulting from retrograde condensation in GCR. The pseudopressure transform, Pedrosa transform, Laplace transform, and Finite Cosine transform are utilized to address the nonlinear partial differential equation. A systematic verification of the semianalytical solution is confirmed through a comparison with the numerical solution from computer modeling group (CMG). We thoroughly explain the physical significance of the various features by identifying the 12 flow regimes of the typical curve. Furthermore, we offer a method for assessing the extent of retrograde condensation and the size of the retrograde condensate region based on the curve's characteristics. Finally, the pressure measurements recorded from the Bohai field are carried out to validate the accuracy of the proposed model. The results show that the predictions of the new model are in good agreement with the actual production data, demonstrating the proposed solution's applicability.
裂缝性凝析气藏是一种复杂、特殊且极具价值的气藏类型，在气藏开发中占比显著。近年来，随着水平井技术的不断进步，其已成为裂缝性凝析气藏开发的主要方式。由于凝析气藏存在独特的反凝析现象，当前模型无法准确描述水平井近井区域的流体分布。此外，裂缝的存在使传统解析模型的求解变得复杂。针对这一问题，本文提出了一种适用于裂缝性凝析气藏水平井的新型半解析模型，该模型考虑了天然裂缝、多相流以及应力敏感性对压力响应的影响。采用双孔模型模拟裂缝性油藏，并建立了四区径向复合模型来描述凝析气藏反凝析产生的多相流。利用拟压力变换、佩德罗斯变换、拉普拉斯变换和有限余弦变换求解非线性偏微分方程。通过与计算机模拟组（CMG）的数值解进行比较，对该半解析解进行了系统验证。通过识别典型曲线的12种流动形态，深入解释了各种特征的物理意义。此外，基于曲线特征，提供了一种评估反凝析程度和反凝析区域大小的方法。最后，利用渤海油田的压力测量数据对所提模型的准确性进行了验证。结果表明，新模型的预测结果与实际生产数据吻合良好，证明了所提解的适用性。
