Dissertation > Excellent graduate degree dissertation topics show

During Coal Reservior Drainage and Physical Simulation of CBM Desorption at Fixed Pressures and Flow in Southern Qinshui Basin

Author: LiuAiHua
Tutor: FuXueHai
School: China University of Mining and Technology
Course: Geological Resources and Geological Engineering
Keywords: CBM hydrochemistry desorption at fixed pressure three-level flow southern Qinshui basin
CLC: TD821
Type: PhD thesis
Year: 2013
Downloads: 77
Quote: 0
Read: Download Dissertation

Abstract


In order to investigate the dynamic change regularities of underground waterduring coal reservoir drainage in southern Qinshui basin and the determination offollow-up CBM desorption, diffusion and flow process to CBM production,“changerate” and “variation velocity”, characterization parameters of dynamic change of ionsconcentration, were put forward to differentiate coal reservoir water systems. Throughdesorption experiments of bulk coal sample at fixed pressures, coal gas and liquidsingle phase permeability, gas-liquid two phases permeability and coal matrixdiffusion coefficient simulation, the three-level flow laws of coal reservoir werediscussed, as well as gas-water desorption and flow features in different drainagestages were revealed.In this paper, coal reservoir water systems were classified into two types, i.e.“connected” and “unconnected”, based on the characterization parameters of dynamicchange characteristics of ion concentration. In a short time, the ionic concentration“change rate” of CBM well water of the “unconnected” type was about two timeslarger than that of the “connected” one. In addition, the difference in the magnitude of“variation velocity” of ion concentration between the two water systems was2-3orders. On the basis of desorption experiments of bulk high-rank coal at step-downpressures,“desorption hysteresis” in micro-pore and transitional pore in high-rankcoal reservoir was considered to result in the fluctuations, rise and decline of threedesorption stages in each pressure-drop stage. What’s more, there exists anexponential relationship between the accumulative desorption rate and abandonmentpressure. Under an abandonment pressure0.7MPa, the accumulative desorption ofhigh-rank coal reservoir, and total desorption amount of step-down-pressuredesorption was1.46higher than that of desorption under normal pressure. Based onstatic simulation of permeability and diffusion coefficient on coal structure ofdifferent space scales, combining with dynamic simulation of coal permeability underthe comprehensive function of effective stress effect, coal matrix shrinkage effect andslippage effect, the coal macro-fracture permeability was defined as high-efficiencypermeability while the coal micro-fracture permeability was defined as low-efficiencypermeability and transitional diffusion mode dominated in all the CBM diffusionmodels. The three-level flow was pointed out to be a continuous flow in the CBMhigh-efficiency flow space, low-efficiency flow space and CBM diffusion space.Based on response characteristics of fluid in the coal reservoir drainage process, in terms of desorption in coal reservoir the drainage process was divided into four stagesi.e.（I） liquid flow,（Ⅱ1+Ⅱ2） unstable desorption,（Ⅲ） stable desorption, and （Ⅳ）attenuation desorption. Stage I: fracturing fluid and gravity water in reservoir poresoutput without CBM desorption. Stage Ⅱ1: the first short peak of gas generationoccurred with the increase of free gas and water soluble gas due to the decrease ofpressure. Stage Ⅱ2: the production reached a low point because of a desorption lag ofadsorbed methane and the reduction of fracture permeability under the function ofeffective stress. Stage Ⅲ: the adsorbed gas desorbed in the micro-pore steadily andthe production gradually increased due to the increase of fracture permeability underthe function of coal matrix shrinkage effect and there went up to the second peak ofgas-generating. Stage Ⅳ: the CBM production gradually reduced due to the differenceof pressure and reduction of concentration difference in the coal matrix, at lastdesorption dried up. The CBM desorption is proceeding from the wellboreprogressive outward in space. Coal reservoir has experienced the four stages ofdesorption and flow process in time and coal reservoir shows the characteristics of therelay gas supply in time and space.

Related Dissertations

  1. Shandong Province, the existing features and coalbed methane resource evaluation,P618.13
  2. Low permeability reservoir fracturing CBM Parameter Optimization,P618.13
  3. Numerical Simulation of Well Patterns Optimization on CBM Development,TE324
  4. Based on CLIPS CBM gathering process fault diagnosis expert system design,TP182
  5. 3G -based mining CBM wells station remote monitoring system,TP277
  6. Occurrence Condition Research of Shaoyang, Hunan Provence Duanpiqiao Mine Area CBM,P618.13
  7. The Exploration on the Mechanism of Multiple Fracture and Acidification in Hydraulic Fracturing of CBM Well,TE357
  8. Research on Controlling of CBM Horizontal Well Production,TE377
  9. Preparation of Gas-geologic Map of Chenzhuang Mine and Coalbed Methane Recource Evaluation,TD712
  10. Development of Condition Based Maintenance Information Management System for Oil-filled Transformer (Reactor),TM411
  11. Nujiang Yuejin Bridge UPON recovery alternative mechanism analysis and Yuejin Bridge Spa,P314.1
  12. Study on Occurrence of Coalbed Methane in Situ and CH4 Compressibility Factor Effect on CH4 Adsorption in Coal,P618.11
  13. Experimental Study on the Explosion Risk of Coal Bed Methane Adsorption Tower,TD712.7
  14. Research on Coal Bed Methane Industry Development Program of Jincheng Anthracite Coal Mining Group Co., Ltd.,F426.2
  15. Reseach on Water Interaction in the Middle Reaches of Heihe River Basin,P333
  16. The Reservoir Characteristics and Genetic Mechanism of Shan Xi Formation 3# Coal in Lu’an Mining Area,P618.11
  17. Study on Features of Coal Reservoir of Southern Yan Chuan Block of Ordos Basin,P618.11
  18. Academic Research about the Coal Bed Methane Combustion Simulation Character in Gasoline Engine,TK411
  19. Analysis on Mechanical Performance of CBM Cast-in-situ Hollow Concrete Floorinfluenced by Geometric Parameters,TU375
  20. Structural Deformation of High Rank Coal and Its Effect on Permeability of Coalbed Methane Enrichment Area in the Southern Section of Qinshui Basin,P618.11
  21. Study on the Trophic Level in the Dishui Lake and the Mutlianalysis Between Chlorophyll-a and Other Environmental Factors,X824

CLC: > Industrial Technology > Mining Engineering > Mining > Coal mining > Theory of coal mining
© 2012 www.DissertationTopic.Net  Mobile