Research on the Production Decline Law of Junlian Coalbed Methane Development Test Well

Yang, Zhao; Sun, Tiezhi; Wang, Meizhu; YongSheng, Han; Mu, Fuyuan; Liu, Lin; Jiang, Bo; Zhang, Jidong

doi:10.1007/s10553-020-01177-9

Cited by 5 publications

(4 citation statements)

References 3 publications

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“…Obviously, the prediction of volume strain in N 2 -ECBM by using adsorption/desorption gas volume has a good effect on reservoirs with a low elastic modulus (E s < 3500), while for reservoirs with a high elastic modulus (E s > 3500), the influence of sample elastic modulus characteristics had to be considered. (3) The slope of the fitting data is medium-> low-> high-rank coal, indicating that the volume strain growth of medium-rank coal changes greatly with the increase of adsorbed methane volume, resulting in the decrease of reservoir permeability with the increase of gas content; however, methane desorption in the process of N 2 -IS will also greatly increase the permeability. The mechanical properties of some low-and high-rank coal reservoirs after long-term drainage and large amounts of gas production will be changed, and the permeability will also be increased after N 2 -IS.…”

Section: Discussionmentioning

confidence: 99%

“…There are three main types of low production wells. In the first type, the CBM content and reservoir pressure of depleted wells have been greatly decreased due to the long-term drainage and production, and the gas production potential has been reduced. , The second type is low permeability and low reservoir pressure wells caused by poor geological conditions of coal reservoirs . The last is caused by reservoir pollution, improper drainage control, and so on, and production can be recovered by refracturing again.…”

Section: Introductionmentioning

confidence: 99%

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Dynamic Monitoring of Induced Strain during N₂-ECBM of Coal with Different Gas Contents

Wang

Deng

et al. 2021

Energy Fuels

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To explore N 2 -enhanced coalbed methane (N 2 -ECBM) recovery with different gas contents, six specimens (R o,ran = 0.42−3.23%) in Shanxi Province, China, were selected to physically simulate N 2 -ECBM recovery via laboratory testing. The volume shrinkage characteristics and desorption percentage (DP) evolution patterns of coal were studied during N 2 injection and sealing (N 2 -IS) and desorption with stepwise depressurization (DSD). The results show that a linear relationship exists between the volume deformation and coal adsorption/desorption gas. The volume strain of specimens with low elastic modulus (E s ) <3500 increases greatly with increasing gas content, which leads to a decrease in reservoir permeability. However, CH 4 desorption will also substantially increase the permeability during N 2 -IS. After long-term gas recovery, the mechanical properties of depleted wells will be reduced, and gas production will resume after N 2 -IS. During the N 2 -IS, the DP of samples with low gas content decreases with increasing micropore volume, and reabsorption appears in highrank coal. The induced strain rate decreases with increasing micropore volume and E s , increases with increasing macropore volume, and increases at first and then decreases with increasing coal rank. During the DSD process, there is no significant difference in DP at each stage, indicating that is the key to stable gas production in N 2 -ECBM recovery. Finally, the cumulative DP was gradually increased by the influence of reservoir gas content. It is revealed that highpressure N 2 -IS can effectively improve gas production for reservoirs with congenital low pressure but well-developed permeability or depleted wells that have experienced a large amount of gas production. For low-permeability reservoirs, high-pressure nitrogen pressure fracturing can be performed first to increase permeability, followed by the N 2 sealing stage.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Dynamic Monitoring of Induced Strain during N₂-ECBM of Coal with Different Gas Contents

Wang

Deng

et al. 2021

Energy Fuels

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“…This leads to an improvement in the production capacity and economic advantage of coalbed methane [21,52]. In addition, it has the capability to forecast the drop in productivity of coalbed methane wells, including the rate at which production decreases and the trend of pressure changes [37,53]. Furthermore, the evaluation of coalbed methane resources is conducted by modeling and assessing the heterogeneity characteristics of coalbed methane reservoirs.…”

Section: Introductionmentioning

confidence: 99%

A Fully Coupled Gas–Water–Solids Mathematical Model for Vertical Well Drainage of Coalbed Methane

Wang,

Zhao,

Liu

et al. 2024

Energies

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The coupling relationship between the deformation field, the diffusion field, and the seepage field is an important factor in fluid transport mechanisms in the long-term coalbed methane (CBM) exploitation process. A mathematical model of gas–water two-phase fluid–structure coupling in a double-porosity medium in coal reservoirs is established in this paper. Taking Hancheng Block, a typical production block in Qinshui Basin, as the geological background critical desorption pressure, reservoir permeability anisotropy is considered in the model. COMSOL Multiphysics (COMSOL_6.0) was used to create the model. The accuracy and rationality of the model were verified by comparing field production data with the results of the simulation. Using the simulation, the influence law of various reservoir geological characteristics parameters (Langmuir strain constant, ratio of critical desorption pressure to reservoir pressure of coal seam (CDPRP), elastic modulus, initial water saturation, Langmuir pressure, etc.) on CBM productivity, reservoir pressure, and permeability ratio was discussed, and a thorough analysis of the factors affecting productivity was obtained using the orthogonal test method. The findings of this study indicate that the change in permeability is the result of the superposition effect of many factors. Different stages of drainage have different primary regulating factors. Rock skeleton stress has a consequence on coal matrix permeability in the early drainage stage, and coal matrix shrinkage is primarily impacted in the later drainage stage. Besides the initial water saturation, other reservoir geological parameters (e.g., CDPRP, Langmuir volume, Langmuir strain constant, elastic modulus) have a strong relationship with productivity. When the value of coal geological parameters increases, the degree of productivity release is higher (as the initial water saturation increases, the production decreases correspondingly). Different coal and rock parameters have varying levels of impact on the drainage stage of CBM wells. The influences of the CDPRP, Langmuir volume, Langmuir strain constant, and elastic modulus on gas production are mainly concentrated in the initial and intermediate drainage stages and begin to fall off during the last drainage stage. Per the multi-factor analysis, the main coal–rock parameters affecting the productivity release are the Langmuir strain constant, followed by the CDPRP and other parameters. The analysis findings can offer theoretical guidance for CBM well selection and layer selection and enhance the block’s overall CBM development level. The improved productivity prediction model for CBM, which is based on fluid–structure coupling theory, can offer a new technical benchmark for CBM well productivity prediction.

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“…For this reason, many scholars have attempted to reveal the mechanism of coal-rock gas production [27][28][29][30][31][32][33][34][35], and the research was mainly focused on coal metamorphism gas production, microbial gas production, biochemical gas production, and gas production by coal's mechanochemical deformation. They verified the metamorphism of coal-rock and the effect of gas generation from the macroscopic and microscopic structure of coal-rock, and explored the gas production mechanism by using experimental methods.…”

Section: Introductionmentioning

confidence: 99%

Development and Application of Gas Production Measurement System of Coal-Rock under Temperature–Pressure Coupling

Wang

et al. 2022

Sensors

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In this study, a measurement system for gas generation of coal-rock under temperature–pressure coupling was developed by adding gas extraction, collection, and flow-monitoring devices to the original stainless-steel liquid seepage pipeline of an MTS-815 rock triaxial testing machine, which can be used to study the production mechanism of coalbed methane in a real geological environment. The system has the functions of axial loading, confining pressure loading, continuous heating, gas gathering, etc., and has the advantages of good air tightness, high accuracy and stability, long-term loading and heating, and controllable single variables. The preliminary test for the gas production of anthracite in the Shaanxi Formation of the Qinshui Basin under temperature–pressure coupling was carried out by the developed test system. The results show that the test system can provide accurate and effective measurement means for the study of gas production by coal-rock deformation and is expected to provide effective help for the control and exploitation of coalbed methane.

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Research on the Production Decline Law of Junlian Coalbed Methane Development Test Well

Cited by 5 publications

References 3 publications

Dynamic Monitoring of Induced Strain during N₂-ECBM of Coal with Different Gas Contents

Dynamic Monitoring of Induced Strain during N₂-ECBM of Coal with Different Gas Contents

A Fully Coupled Gas–Water–Solids Mathematical Model for Vertical Well Drainage of Coalbed Methane

Development and Application of Gas Production Measurement System of Coal-Rock under Temperature–Pressure Coupling

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Research on the Production Decline Law of Junlian Coalbed Methane Development Test Well

Cited by 5 publications

References 3 publications

Dynamic Monitoring of Induced Strain during N2-ECBM of Coal with Different Gas Contents

Dynamic Monitoring of Induced Strain during N2-ECBM of Coal with Different Gas Contents

A Fully Coupled Gas–Water–Solids Mathematical Model for Vertical Well Drainage of Coalbed Methane

Development and Application of Gas Production Measurement System of Coal-Rock under Temperature–Pressure Coupling

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Dynamic Monitoring of Induced Strain during N₂-ECBM of Coal with Different Gas Contents

Dynamic Monitoring of Induced Strain during N₂-ECBM of Coal with Different Gas Contents