IMECH-IR  > 流固耦合系统力学重点实验室
煤层气气-水两相渗流研究及应用
英文题名Research on Gas-Water Two-Phase Flow in Coalbed Methane Reservoirs and Application
侯绍继1,2
导师刘曰武
2018-05-17
学位授予单位中国科学院大学
学位授予地点北京
学位类别硕士
学位专业工程力学
关键词煤层气藏 吸附解吸 气-水两相渗流 生产数据分析 反褶积算法
摘要

随着全世界能源的紧缺和全球各国对非常规天然气资源勘探开发程度的逐步加深,煤层气藏的开发已经成为一项重要且有意义的课题。

煤层气作为清洁能源绝大部分气体都吸附在煤岩中。煤层气的开发过程是通过排水方式使煤层的压力慢慢下降,当压力比临界解吸压力更低时,煤层气从煤层中解吸出来而进行排采生产的。在排采过程,煤层中的流体由单相水流变为气-水两相流动,经过较长时间之后最终达到单相气流状态。气-水两相流动是煤层气排采过程中的主要阶段,因此,煤层气气-水两相渗流的研究是高效合理开发煤层气资源的理论基础和开发技术的重要依据。

但是,目前国内外关于煤层气气-水两相渗流的研究并不多。本文对煤层气气-水两相渗流的研究主要从以下4各方面进行:

(1)在回顾了煤层气井单相渗流的定常与非定常渗流的研究成果的基础上,采用了拟压力的处理方法建立了考虑解吸附作用的气-水两相混相稳定渗流与不稳定渗流模型,采用了非结构网格有限体积方法,并对模型进行离散求解。分析了不同种类的煤层气井的试井曲线及压力场云图。

(2)根据改进的煤层气藏开发过程中的稳定解吸与不稳定解吸模型,结合考虑压力敏感及气水饱和度分布的渗透率关系,提出了一种新的考虑多种因素下的气-水两相分相不稳定渗流模型,分析了解吸区域大小、井底气饱和度、压力敏感等因素对试井理论曲线的影响。

(3)为了对现场煤层气井的测试资料进行分析和对实际煤层气井的地层参数进行预测,本论文对目前使用的反褶积方法进行改进,通过分段积分与解析法求解积分的结合提高了算法的运算速度;通过引入von Schroeter等人反褶积算法中的“曲率最小化”增加了相应的非线性约束条件,进一步提高压力反褶积算法压力导数计算的稳定性。

(4)通过现场实例数据分析,获得了煤层气井气-水两相渗流阶段的煤层参数以及产量变化规律,验证了本文提出的模型的正确性以及改进反褶积算法的有效性。

英文摘要

With the shortage of energy in the world and the gradual deepening of the exploration and development of unconventional natural gas resources in various countries around the world, the development of coalbed methane (CBM) reservoirs has become an important and significant issue.

CBM as a clean energy is mainly present in the coal seam in an adsorbed state. The process of CBM drainage is drained to lower the pressure of the coal seam below the critical desorption pressure, and CBM is produced by desorption from the coal seam. In the process of production, the fluid in the coal seam changes from water single-phase flow to gas-water two-phase flow and finally reaches the single-phase flow state after a long time. The gas-water two-phase flow is the main stage in CBM drainage process. Therefore, the study on CBM water two-phase seepage is an important basis for the theoretical basis and development technology for efficient and reasonable development of CBM resources.

However, there are few researches on the theory of CBM water two-phase seepage.In this paper, the study on CBM water two-phase seepage mainly proceeds from the following four aspects:

(1) On the basis of reviewing the research results of steady and unsteady seepage of single-phase seepage flow in CBM wells. A pseudo-pressure method was used to establish the steady and unsteady mixed phase seepage model of gas-water two-phase considering desorption. The unstructured grid finite volume method was used to solve the model numerically. The well test curves and coal seam pressure field maps of different types of CBM wells are analyzed.

(2) Based on the improved stable desorption and unstable desorption models in the development process of CBM reservoirs, taking into account the relationship between pressure sensitivity and the permeability of gas-water saturation distribution, a new gas-water two phase flow model considering multiple factors was proposed. The phase-separated unstable percolation model was used to analyze the influence of the suction zone size, bottomhole gas saturation, pressure sensitivity and other factors on the well test theoretical curve.

(3) In order to analyze the test data of CBM wells in the field and predict the actual production capacity of CBM wells, this paper improves on the deconvolution algorithms currently used and improves the algorithm through the combination of integral and analytic solution integral . By introducing "minimization of curvature" in the deconvolution algorithm of von Schroeter et al., The corresponding nonlinear constraints are added to further improve the stability of the pressure derivative calculation of the pressure deconvolution algorithm.

(4) Through the analysis of a large number of data in the field, the coal seam parameters of gas-water two-phase flow in CBM well and the law of production change is obtained. The correctness of the model and the effectiveness of the deconvolution algorithm was verified.

语种中文
文献类型学位论文
条目标识符http://dspace.imech.ac.cn/handle/311007/73173
专题流固耦合系统力学重点实验室
作者单位1.中国科学院力学研究所
2.中国科学院大学
推荐引用方式
GB/T 7714
侯绍继. 煤层气气-水两相渗流研究及应用[D]. 北京. 中国科学院大学,2018.
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