A new numerical well test method of multi-scale discrete fractured tight sandstone gas reservoirs and its application in the Kelasu Gas Field of the Tarim Basin

IF 4.2 3区 工程技术 Q2 ENERGY & FUELS
Hedong Sun , Weiping Ouyang , Songbai Zhu , Yizhao Wan , Yongliang Tang , Wen Cao
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Abstract

The cretaceous gas reservoir in Kelasu Gas Field of the Tarim Basin is a rare ultra-deep and ultra-high pressure fractured tight sandstone gas reservoir where multi-scale discrete fractures of matrix, fracture and fault are developed, so its development cannot be conducted just based on static and dynamic reservoir description. In order to solve this problem, this paper establishes a numerical well test model of vertical wells based on matrix, fractures and faults (large fractures and small faults) by combining the random generation of natural fracture networks with the unstructured discrete fracture modeling method to break through the traditional continuous medium well test model. In addition, the model is solved by using the finite element method with mixed element, and the typical well test type curves under different random fracture networks are obtained. And the following research results are obtained. First, based on the observed data, the fracture network distribution modes of fractured tight sandstone gas reservoirs are classified into three categories. The influence of random generation of fracture networks on typical well test type curves is discussed. The results of discrete fracture well test model are compared with those of the traditional continuous medium well test model, and the applicable conditions of the traditional continuous medium well test model is determined. Second, there are great differences between the results of discrete fracture model and those of dual porosity medium model. 1 The dual porosity medium model is a special case of the discrete fracture model, in which the fractures are evenly distributed within infinitely small spacing. Third, the characteristics of well test type curves under three fracture network distribution modes are discussed. The well test type curves that cannot be interpreted by the conventional dual/triple porosity continuous medium model are successfully interpreted by using the established well test interpretation model of random discrete fracture. The curve matching effect is ideal and the interpreted parameters are reasonable. In conclusion, the new model and the new method reveal the development mechanism of step-by-step production and coordinated gas supply between media of different scales, explain the development characteristics of large inter-well productivity difference and abnormal rapid inter-well pressure response, and provide a reference for the development of similar gas reservoirs.

多尺度离散裂缝性致密砂岩气藏数值试井新方法及其在塔里木盆地克拉苏气田的应用
塔里木盆地克拉苏气田白垩系气藏是一个罕见的超深特高压裂缝性致密砂岩气藏,其基质、裂缝、断层等多尺度离散裂缝发育,不能仅凭储层的静态和动态描述进行开发。为了解决这一问题,本文将自然裂缝网络的随机生成与非结构化离散裂缝建模方法相结合,突破传统的连续介质试井模型,建立了基于矩阵、裂缝和断层(大裂缝和小断层)的直井数值试井模型。此外,采用混合单元有限元法对模型进行了求解,得到了不同随机裂缝网络下的典型试井类型曲线。并得出以下研究结果。首先,根据观测资料,将裂缝性致密砂岩气藏的裂缝网络分布模式分为三类。讨论了裂缝网络的随机生成对典型试井类型曲线的影响。将离散裂缝试井模型与传统连续介质试井模型的结果进行了比较,确定了传统连续介质测井模型的适用条件。其次,离散裂缝模型的结果与双重孔隙介质模型的结果存在很大差异。1双重孔隙介质模型是离散裂缝模型的一种特殊情况,其中裂缝在无限小的间距内均匀分布。第三,讨论了三种裂缝网络分布模式下的试井类型曲线特征。利用所建立的随机离散裂缝试井解释模型,成功地解释了传统双/三孔连续介质模型无法解释的试井类型曲线。曲线匹配效果理想,解释参数合理。总之,新模型和新方法揭示了不同规模介质分步生产、协调供气的开发机制,解释了井间产能差异大、井间压力响应异常快速的开发特征,为类似气藏的开发提供了参考。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
Natural Gas Industry B
Natural Gas Industry B Earth and Planetary Sciences-Geology
CiteScore
5.80
自引率
6.10%
发文量
46
审稿时长
79 days
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