|Alternative Title||Research on Gas-Water Two-Phase Flow in Coalbed Methane Reservoirs and Application|
|Place of Conferral||北京|
|Keyword||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|
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.
|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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