The Experts below are selected from a list of 279 Experts worldwide ranked by ideXlab platform

Dameng Liu - One of the best experts on this subject based on the ideXlab platform.

  • the impacts of flow velocity on permeability and porosity of coals by core flooding and nuclear magnetic resonance implications for Coalbed Methane Production
    Journal of Petroleum Science and Engineering, 2018
    Co-Authors: Zhengshuai Liu, Yidong Cai, Dameng Liu, Zhejun Pan
    Abstract:

    Abstract The fluid flow velocity has a significant effect on the Coalbed Methane (CBM) Production by influencing the porosity and permeability of coals during the drainage process. In this work, the fluid velocity sensitivity experiments combined with the nuclear magnetic resonance (NMR) technology were performed to investigate the impacts of various flow velocities on permeability and porosity. The results show that the permeability of different rank coals has various characteristics with the increase of flow velocity. For low rank coals, the permeability always increases first then decreases with the increase of flow velocity. However, the permeability gradually decreases with the increase of flow velocity for medium and high rank coals. For the same rank coals, the higher initial permeability is, the more severe permeability damage is. Additionally, the porosity variation reflected by NMR T2 spectrum indicates that T2 between 10 ms and 200 ms is the main reduction space of seepage paths. The influence of flow velocity on permeability is mainly due to the blockage of fluid seepage space by coal fines. Moreover, the effects of dewatering rate on CBM Production were further discussed combined with field Production wells. The dropping rate of working fluid level at the single-phase water stage plays an important role on the Production of coal fines and gas Production, especially at the late Production stage. Decreasing dewatering rate at the two-phase (water and gas) stage can improve the CBM Production effectively. To improve the effect of flow velocity on petrophysical properties of CBM reservoir, the dewatering rate of CBM wells should be slow and stable. Therefore, this study could be conducive to CBM Production or mining safety.

  • Petrographic Controls on Pore and Fissure Characteristics of Coals from the Southern Junggar Coalfield, Northwest China
    MDPI AG, 2018
    Co-Authors: Sandong Zhou, Dameng Liu, Yidong Cai, Zuleima Karpyn, Yanbin Yao
    Abstract:

    The productive potential of Coalbed Methane projects is controlled by pore and fissure characteristics, which are intrinsically related to coal petrology. This work attempts to identify the influence of petrographic factors on the development of pore and fissure systems in the southern Junggar Coalfield, Northwest China. Here, Middle Jurassic coal (lignite and subbituminous) petrology in coal seam No. 45 of the southern Junggar Coalfield (SJC) is studied with respect to the characteristics of pore and fissure structure with the aid of optical microscopes, scanning electron microscopy, mercury intrusion porosimetry, and nuclear magnetic resonance analysis. Maceral analysis shows coals at the SJC are dominated by vitrinite (38–87 vol %), with moderate quantities of inertinite (1–28 vol %) and liptinite (0.5–30 vol %). Decomposition of plants occurs under slightly oxic–anoxic conditions, with good tissue retention. Four types of coal facies are classified using petrographic indices, comprising (1) lower delta plain marsh, (2) lower delta plain fen, (3) upper delta plain wet forest swamp; and (4) piedmont plain moor. Pores and fissures are generally observed in telinite, collotelinite, fusinite, and semifusinite in SJC coals, indicating that the generation of pores and fissures is strongly influenced by coal macerals. Pore and fissure structures of coals in coal facies (1) appear weakly connected, whereas those in coal facies (2) reveal good connectivity. Coals in coal facies (3) and (4) show moderate connectivity between pore and fissure structure. Therefore, pore and fissure structures are significantly controlled by coal facies. This work provides practical recommendations and implementation methods for petrological studies in future Coalbed Methane exploration/development in the SJC. This study also serves to predict the physical properties of pores and fissures and interpret the control mechanism of Coalbed Methane Production using coal petrology

  • dynamic permeability change during Coalbed Methane Production and its controlling factors
    Journal of Natural Gas Science and Engineering, 2015
    Co-Authors: Yaxi Chen, Dameng Liu, Yidong Cai, Yanbin Yao, Longwei Chen
    Abstract:

    Abstract Coal reservoir permeability, which changes constantly during the exploitation process, is a key factor for determining the Production effects and ultimate recovery of Coalbed Methane (CBM) wells. To calculate the dynamic permeability more accurately, we reviewed the controlling mechanism of coal reservoir permeability and then established three mathematic permeability change models considering the effective stress, matrix shrinkage and gas slippage respectively. Relation between the Production data and permeability by adopting the material balance theory was established and then a Production data-based theoretical model for calculating the permeability change during the drainage process was derived. Seventeen wells from the Fanzhuang–Zhengzhuang block in the southern Qinshui Basin of China were employed for a case study. The calculated results clearly reflect the dynamic permeability change. The dynamic permeability curves can be divided into “decline type”, “rebound type” and “rising type”. Furthermore, the impacts of pressure drop, daily gas Production, and final pressure on permeability change were analyzed. The results show that the rate of permeability change induced by effective stress had a significant positive linear correlation with the pressure drops. A quadratic relationship existed between the rate of permeability change induced by matrix shrinkage and daily gas Production rate. The lower final pressure will give rise to the faster permeability change that induced by gas slippage, which indicates a typically exponential relationship.

  • characteristics of coal matrix compressibility an investigation by mercury intrusion porosimetry
    Energy & Fuels, 2014
    Co-Authors: Xiaoqian Guo, Yanbin Yao, Dameng Liu
    Abstract:

    Coal matrix compressibility caused by a pressure change is an important parameter in evaluating the permeability change during Coalbed Methane Production. In this study, the pressure-driven coal matrix compressibility for 21 coals in the rank range from high-volatile A bituminous (0.65% Ro,m) to low-volatile bituminous (1.77% Ro,m) was evaluated by combining the results from mercury intrusion porosimetry (MIP) with N2 adsorption analysis. The pressure interval was chosen to be from 7.35 MPa to ensure that the compression is totally from the coal matrix. The calculated coal matrix compressibility shows a U-shaped relationship with increasing coal rank, and it obtains relatively low values at the medium-volatile bituminous coals. The coal matrix compressibility of high-volatile A bituminous coals is of 1.6398–2.9060 × 10–4 MPa–1, and medium- and low-volatile bituminous coals have coal matrix compressibility of 0.3451–1.5519 × 10–4 and 0.7625–2.5554 × 10–4 MPa–1, respectively. Moreover, with the data of petr...

  • preliminary evaluation of the Coalbed Methane Production potential and its geological controls in the weibei coalfield southeastern ordos basin china
    International Journal of Coal Geology, 2009
    Co-Authors: Yanbin Yao, Dazhen Tang, Dameng Liu, Shuheng Tang, Yao Che, Wenhui Huang
    Abstract:

    article i nfo The Coalbed Methane (CBM) geology, resource and Production potential in the Weibei Coalfield, southeastern Ordos Basin are studied based on geological surveys and laboratory measurements. The results showed that coal rank varies both laterally and vertically and changes from volatile bituminous coals in the margin to anthracites towards the basin (1.6-2.5% Ro). Coals are composed of 60-85% vitrinite, 15-40% inertinite and a trace amount of minerals. Methane isothermal adsorption measurements of 20 coal samples revealed that the maximum adsorption capacity (on a dry and ash-free basis) of coals, which are affected by coal rank, coal maceral, coal lithotype and especially to the moisture content, varies from 13.91 to 29.54 m 3 /t. Estimated gas contents range from 0 to 15 m

Dazhen Tang - One of the best experts on this subject based on the ideXlab platform.

  • Coalbed Methane Production of a heterogeneous reservoir in the ordos basin china
    Journal of Natural Gas Science and Engineering, 2020
    Co-Authors: Yulong Liu, Jonathan P. Mathews, Dazhen Tang, Wei Hou, Xia Yan, Feifei Ding
    Abstract:

    Abstract Macrolithotypes control the pore-fracture distribution heterogeneity in coal impacting gas adsorption, diffusion coefficient, and the gas flow. However, the behaviors that are impacted by coal macrolithotype are traditionally ignored and the drainage radius that linked to the macrolithotype contributions are lack of systematic research all the way. Thus, to evaluate the gas Production relationship for macrolithotype, four blocks (bright, semi-bright, semi-dull, and dull) were obtained from the same seam. The Methane absorption, diffusion, and permeability data were obtained and used in mathematical modeling to identify well Production, drainage radius, and well-interference locations. Production data for 104 wells and 11 test wells were also obtained and with COMET3 simulation software to validate the mathematical model. From the bright to dull coal: there was a lower micropore contribution, a lower gas capacity, and lower gas diffusion coefficient. The cleat frequency and aperture differences impacted the reservoir permeability with bright coal having 195% higher than the dull coal. As these macrolithotype differences impact the Coalbed Methane (CBM) development and cause heterogeneous gas flow systems within the resource, a coupled mathematical model for comprehensive consideration of the adsorbent-diffusion-seepage was established capturing the macrolithotype contribution to the pressure propagation, gas flow, and gas drainage radius estimation. The bright coal had the higher Langmuir volume, CH4 diffusion coefficient, and permeability thus, producing a higher gas Production volume, and a larger gas drainage area than the dull macrolithotype. Thus, the macrolithotype diversity and its stratification cause partitioning of the gas flow with multi-stage pressure drop effecting exploration and development. In addition, the well interference was also observed and show that the wells of bright and semi-bright coal have a continuous pressure drop, which achieving the purpose of overall pressure reduction.

  • High Production indexes and the key factors in Coalbed Methane Production: A case in the Hancheng block, southeastern Ordos Basin, China
    Journal of Petroleum Science and Engineering, 2015
    Co-Authors: Junlong Zhao, Dazhen Tang, Hao Xu, Yumin Lv
    Abstract:

    Abstract An understanding of gas well productivity in coal reservoirs is vital for the recovery of Coalbed Methane (CBM). The Hancheng Block has become one of the most productive CBM areas in China. Relatively few studies have investigated the productivity and key controls of CBM wells in the coal reservoir. In this work, with an analysis of the Production characteristics of the CBM wells that have been producing for more than 2 yr in the Hancheng Block of the southeastern Ordos Basin, the correlations between various factors and numerous gas Production data were analyzed by correlation scatter diagrams. The effect of six factors (the burial depth, the thickness of the coal seam, the ratio of the critical desorption pressure to the initial reservoir pressure, the gas content, the permeability and the effect of fracturing) on gas Production was evaluated quantitatively based on the grey system theory, which is suitable for solving the complex interrelationships between multiple factors and variables. The results indicate that the Hancheng Block is in the early stage of development. The factors affecting gas Production of the CBM wells are, in decreasing order, the ratio of the critical desorption pressure to the initial reservoir pressure, the volume of the fracturing fluid per meter, the gas content, the volume of the fracturing sand per meter, the thickness, the permeability and the depth. Among these factors, the ratio of the critical desorption pressure to the initial reservoir pressure determines frequently the degree of difficulty of the water drainage and decompression; the gas Production potential (the thickness×the gas content) and the gas Production deliverability (the gas Production potential×the permeability) could characterize the comprehensive effect of the thickness of the coal seam, the gas content and the permeability on gas well productivity. Higher ratio of the critical desorption pressure to the initial reservoir pressure, higher gas Production potential and deliverability are more favorable for gas productivity. Hydraulic fracturing has always been an indispensable part of the development of CBM fields. In combination with gas well Production performance, the parameter indexes of high Production CBM wells are presented as follows: the buried depth range should be 400–700 m; the thickness of the coal seam should not be lower than 5 m; the ratio of the critical desorption pressure to the initial reservoir pressure should be greater than 0.3; the gas content should be greater than 6 m 3 /t; the volume of the fracturing fluid per meter should not be less than 40 m 3 /m; the volume of fracturing sand per meter should not be less than 3 m 3 /m; and 1% KCl active water fracturing fluid should be used as the fracturing fluid.

  • geological controls and Coalbed Methane Production potential evaluation a case study in liulin area eastern ordos basin china
    Journal of Natural Gas Science and Engineering, 2014
    Co-Authors: Yanjun Meng, Dazhen Tang, Shangzhi Meng
    Abstract:

    Abstract The Liulin area in the eastern Ordos Basin is one of the optimum areas for medium-rank Coalbed Methane (CBM) exploration and development in China. This work investigated the CBM geology and accumulation characteristics of No.4 coal in the Permian Shanxi Formation in the Liulin area based on data from 29 coal mining wells, 25 CBM wells and 14 coal samples. The results show that coal rank (medium volatile bituminous and low volatile bituminous) varies laterally, with the maximum vitrinite reflectance (Ro, max) ranges from 1.23 to 1.90%. Coals are dominated by vitrinite (47.9–90.5%); followed by inertinite (7.7–50.5%) and liptinite (0–0.6%). Minerals account for only a small proportion (0.4%–16.5%, avg. 4.7%). The results of well tests show that the coal permeability ranges from 0.02 to 3.44 mD, and the reservoir pressure ranges from 2.58 to 9.26 MPa. Most coal pores are less than 100 nm in diameter, and are favorable for gas adsorption but unfavorable for gas flow. Microfractures of coals are characterized by dendritic and step-shaped structures, relatively good connectivity, directionality and infrequent mineralization. The dominated types of microfractures are type C (less than 5 μm wide and more than 300 μm long) and type D (less than 5 μm wide and 300 μm long), with a large span of frequency ranging from 18 to 78 per 9 cm2. Methane adsorption isothermal measurements reveal that their maximum adsorption capacity (dry ash-free) vary from 21.36 to 26.38 m3/t. The in-place gas content is generally 4.93–14.96 m3/t. In combination with the geological information, the data reveals that structure properties, coal roof lithology and hydrogeology conditions have important influences on gas accumulation, preservation and enrichment. Furthermore, integrated geographical information system (GIS) and analytical hierarchy fuzzy prediction method (AHP) are used to evaluate the CBM Production potential in the Liulin area. The best prospective target area for CBM Production is forecasted to be located in the central slope belt (near southern Beilijiyuan and Yangjiayu areas) of the Liulin area.

  • a dynamic prediction model for gas water effective permeability based on Coalbed Methane Production data
    International Journal of Coal Geology, 2014
    Co-Authors: Dazhen Tang, Junlong Zhao, Shuling Tang, Yanjun Meng, Shu Tao
    Abstract:

    Abstract An understanding of the relative permeability of gas and water in coal reservoirs is vital for Coalbed Methane (CBM) development. In this work, a prediction model for gas–water effective permeability is established to describe the permeability variation within coal reservoirs during Production. The effective stress and matrix shrinkage effects are taken into account by introducing the Palmer and Mansoori (PM) absolute permeability model. The endpoint relative permeability is calibrated through experimentation instead of through the conventional Corey relative permeability model, which is traditionally employed for the simulation of petroleum reservoirs. In this framework, the absolute permeability model and the relative permeability model are comprehensively coupled under the same reservoir pressure and water saturation conditions through the material balance equation. Using the Qinshui Basin as an example, the differences between the actual curve that is measured with the steady-state method and the simulation curve are compared. The model indicates that the effective permeability is expressed as a function of reservoir pressure and that the curve shape is controlled by the Production data. The results illustrate that the PM–Corey dynamic prediction model can accurately reflect the positive and negative effects of coal reservoirs. In particular, the model predicts the matrix shrinkage effect, which is important because it can improve the effective permeability of gas Production and render the process more economically feasible.

  • preliminary evaluation of the Coalbed Methane Production potential and its geological controls in the weibei coalfield southeastern ordos basin china
    International Journal of Coal Geology, 2009
    Co-Authors: Yanbin Yao, Dazhen Tang, Dameng Liu, Shuheng Tang, Yao Che, Wenhui Huang
    Abstract:

    article i nfo The Coalbed Methane (CBM) geology, resource and Production potential in the Weibei Coalfield, southeastern Ordos Basin are studied based on geological surveys and laboratory measurements. The results showed that coal rank varies both laterally and vertically and changes from volatile bituminous coals in the margin to anthracites towards the basin (1.6-2.5% Ro). Coals are composed of 60-85% vitrinite, 15-40% inertinite and a trace amount of minerals. Methane isothermal adsorption measurements of 20 coal samples revealed that the maximum adsorption capacity (on a dry and ash-free basis) of coals, which are affected by coal rank, coal maceral, coal lithotype and especially to the moisture content, varies from 13.91 to 29.54 m 3 /t. Estimated gas contents range from 0 to 15 m

Yanbin Yao - One of the best experts on this subject based on the ideXlab platform.

  • Petrographic Controls on Pore and Fissure Characteristics of Coals from the Southern Junggar Coalfield, Northwest China
    MDPI AG, 2018
    Co-Authors: Sandong Zhou, Dameng Liu, Yidong Cai, Zuleima Karpyn, Yanbin Yao
    Abstract:

    The productive potential of Coalbed Methane projects is controlled by pore and fissure characteristics, which are intrinsically related to coal petrology. This work attempts to identify the influence of petrographic factors on the development of pore and fissure systems in the southern Junggar Coalfield, Northwest China. Here, Middle Jurassic coal (lignite and subbituminous) petrology in coal seam No. 45 of the southern Junggar Coalfield (SJC) is studied with respect to the characteristics of pore and fissure structure with the aid of optical microscopes, scanning electron microscopy, mercury intrusion porosimetry, and nuclear magnetic resonance analysis. Maceral analysis shows coals at the SJC are dominated by vitrinite (38–87 vol %), with moderate quantities of inertinite (1–28 vol %) and liptinite (0.5–30 vol %). Decomposition of plants occurs under slightly oxic–anoxic conditions, with good tissue retention. Four types of coal facies are classified using petrographic indices, comprising (1) lower delta plain marsh, (2) lower delta plain fen, (3) upper delta plain wet forest swamp; and (4) piedmont plain moor. Pores and fissures are generally observed in telinite, collotelinite, fusinite, and semifusinite in SJC coals, indicating that the generation of pores and fissures is strongly influenced by coal macerals. Pore and fissure structures of coals in coal facies (1) appear weakly connected, whereas those in coal facies (2) reveal good connectivity. Coals in coal facies (3) and (4) show moderate connectivity between pore and fissure structure. Therefore, pore and fissure structures are significantly controlled by coal facies. This work provides practical recommendations and implementation methods for petrological studies in future Coalbed Methane exploration/development in the SJC. This study also serves to predict the physical properties of pores and fissures and interpret the control mechanism of Coalbed Methane Production using coal petrology

  • dynamic permeability change during Coalbed Methane Production and its controlling factors
    Journal of Natural Gas Science and Engineering, 2015
    Co-Authors: Yaxi Chen, Dameng Liu, Yidong Cai, Yanbin Yao, Longwei Chen
    Abstract:

    Abstract Coal reservoir permeability, which changes constantly during the exploitation process, is a key factor for determining the Production effects and ultimate recovery of Coalbed Methane (CBM) wells. To calculate the dynamic permeability more accurately, we reviewed the controlling mechanism of coal reservoir permeability and then established three mathematic permeability change models considering the effective stress, matrix shrinkage and gas slippage respectively. Relation between the Production data and permeability by adopting the material balance theory was established and then a Production data-based theoretical model for calculating the permeability change during the drainage process was derived. Seventeen wells from the Fanzhuang–Zhengzhuang block in the southern Qinshui Basin of China were employed for a case study. The calculated results clearly reflect the dynamic permeability change. The dynamic permeability curves can be divided into “decline type”, “rebound type” and “rising type”. Furthermore, the impacts of pressure drop, daily gas Production, and final pressure on permeability change were analyzed. The results show that the rate of permeability change induced by effective stress had a significant positive linear correlation with the pressure drops. A quadratic relationship existed between the rate of permeability change induced by matrix shrinkage and daily gas Production rate. The lower final pressure will give rise to the faster permeability change that induced by gas slippage, which indicates a typically exponential relationship.

  • characteristics of coal matrix compressibility an investigation by mercury intrusion porosimetry
    Energy & Fuels, 2014
    Co-Authors: Xiaoqian Guo, Yanbin Yao, Dameng Liu
    Abstract:

    Coal matrix compressibility caused by a pressure change is an important parameter in evaluating the permeability change during Coalbed Methane Production. In this study, the pressure-driven coal matrix compressibility for 21 coals in the rank range from high-volatile A bituminous (0.65% Ro,m) to low-volatile bituminous (1.77% Ro,m) was evaluated by combining the results from mercury intrusion porosimetry (MIP) with N2 adsorption analysis. The pressure interval was chosen to be from 7.35 MPa to ensure that the compression is totally from the coal matrix. The calculated coal matrix compressibility shows a U-shaped relationship with increasing coal rank, and it obtains relatively low values at the medium-volatile bituminous coals. The coal matrix compressibility of high-volatile A bituminous coals is of 1.6398–2.9060 × 10–4 MPa–1, and medium- and low-volatile bituminous coals have coal matrix compressibility of 0.3451–1.5519 × 10–4 and 0.7625–2.5554 × 10–4 MPa–1, respectively. Moreover, with the data of petr...

  • preliminary evaluation of the Coalbed Methane Production potential and its geological controls in the weibei coalfield southeastern ordos basin china
    International Journal of Coal Geology, 2009
    Co-Authors: Yanbin Yao, Dazhen Tang, Dameng Liu, Shuheng Tang, Yao Che, Wenhui Huang
    Abstract:

    article i nfo The Coalbed Methane (CBM) geology, resource and Production potential in the Weibei Coalfield, southeastern Ordos Basin are studied based on geological surveys and laboratory measurements. The results showed that coal rank varies both laterally and vertically and changes from volatile bituminous coals in the margin to anthracites towards the basin (1.6-2.5% Ro). Coals are composed of 60-85% vitrinite, 15-40% inertinite and a trace amount of minerals. Methane isothermal adsorption measurements of 20 coal samples revealed that the maximum adsorption capacity (on a dry and ash-free basis) of coals, which are affected by coal rank, coal maceral, coal lithotype and especially to the moisture content, varies from 13.91 to 29.54 m 3 /t. Estimated gas contents range from 0 to 15 m

Duane H Smith - One of the best experts on this subject based on the ideXlab platform.

  • shrinkage and swelling of coal induced by desorption and sorption of fluids theoretical model and interpretation of a field project
    International Journal of Coal Geology, 2009
    Co-Authors: Raj K Gondle, Hema Siriwardane, Duane H Smith
    Abstract:

    Abstract Geologic sequestration in deep unmineable coal seams and enhanced Coalbed Methane Production is a promising choice, economically and environmentally, to reduce anthropogenic gases such as carbon dioxide in the atmosphere. Unmineable coal seams are typically known to adsorb large amounts of carbon dioxide in comparison to the sizeable amounts of sorbed Methane, which raises the potential for large scale sequestration projects. During the process of sequestration, carbon dioxide is injected into the Coalbed and desorbed Methane is produced. The coal matrix is believed to shrink when a gas is desorbed and swell when a gas is sorbed, sometimes causing profound changes in the cleat porosity and permeability of the coal seam. These changes may have significant impact on the reservoir performance. Therefore, it is necessary to understand the combined influence of swelling and shrinkage, and geomechanical properties including elastic modulus, cleat porosity, and permeability of the reservoir. The present paper deals with the influence of swelling and shrinkage on the reservoir performance, and the geomechanical response of the reservoir system during the process of geologic sequestration of carbon dioxide and enhanced Coalbed Methane Production in an actual field project located in northern New Mexico. A three-dimensional swelling and shrinkage model was developed and implemented into an existing reservoir model to understand the influence of geomechanical parameters, as well as swelling and shrinkage properties, on the reservoir performance. Numerical results obtained from the modified simulator were compared to available measured values from that site and previous studies. Results show that swelling and shrinkage, and the combination of geomechanical and operational parameters, have a significant influence on the performance of the reservoir system.

  • effects of matrix shrinkage and swelling on the economics of enhanced Coalbed Methane Production and co2 sequestration in coal
    Spe Reservoir Evaluation & Engineering, 2007
    Co-Authors: Fatna Gorucu, Sinisha A Jikich, Grant S Bromhal, Turgay Ertekin, Neal W Sams, Duane H Smith
    Abstract:

    In this work, the Palmer-Mansoori model for coal shrinkage and permeability increases during primary Methane Production was rewritten to also account for coal swelling caused by CO{sub 2} sorption. The generalized model was added to a compositional, dual porosity Coalbed-Methane reservoir simulator for primary (CBM) and ECBM Production. A standard five-spot of vertical wells and representative coal properties for Appalachian coals was used. Simulations and sensitivity analyses were performed with the modified simulator for nine different parameters, including coal seam and operational parameters and economic criteria. The coal properties and operating parameters that were varied included Young's modulus, Poisson's ratio, cleat porosity, and injection pressure. The economic variables included CH{sub 4}, price, Col Cost, CO{sub 2} credit, water disposal cost, and interest rate. Net-present value (NPV) analyses of the simulation results included profits resulting from CH{sub 4}, Production and potential incentives for sequestered CO{sub 2}, This work shows that for some coal seams, the combination of compressibility, cleat porosity, and shrinkage/swelling of the coal may have a significant impact on project economics.

  • field project designs for carbon dioxide sequestration and enhanced Coalbed Methane Production
    Energy & Fuels, 2005
    Co-Authors: Neal W Sams, Sinisha A Jikich, Grant S Bromhal, Turgay Ertekin, Duane H Smith
    Abstract:

    Worldwide concerns about global warming and possible contributions to it from anthropogenic carbon dioxide have become important during the past several years. Coal seams may make excellent candidates for CO{sub 2} sequestration; coal-seam sequestration could enhance Methane Production and improve sequestration economics. Reservoir-simulation computations are an important component of any engineering design before carbon dioxide is injected underground. We have performed such simulations for a hypothetical pilot-scale project in representative coal seams. In these simulations we assume four horizontal Production wells that form a square, that is, two wells drilled at right angles to each other forming two sides of a square, with another pair of horizontal wells similarly drilled to form the other two sides. Four shorter horizontal wells are drilled from a vertical well at the center of the square, forming two straight lines orthogonal to each other. By modifying coal properties, especially sorption rate, we have approximated different types of coals. By varying operational parameters, such as injector length, injection well pressure, time to injection, and Production well pressure, we can evaluate different Production schemes to determine an optimum for each coal type. Any optimization requires considering a tradeoff between total CO{sub 2} sequestered and the ratemore » of Methane Production. Values of total CO{sub 2} sequestered and Methane produced are presented for multiple coal types and different operational designs. 30 refs., 11 figs., 1 tab.« less

  • matrix shrinkage and swelling effects on economics of enhanced Coalbed Methane Production and co2 sequestration in coal
    Society of Petroleum Engineers Eastern Regional Meeting 2005, 2005
    Co-Authors: Fatna Gorucu, Sinisha A Jikich, Grant S Bromhal, W Sams, Turgay Ertekin, Duane H Smith
    Abstract:

    Increases in CO2 levels in the atmosphere and their contributions to global climate change have been a major concern. It has been shown that CO2 injection can enhance the Methane recovery from coal. Accordingly, sequestration costs can be partially offset by the value added product. Indeed, coal seam sequestration may be profitable, particularly with the introduction of incentives for CO2 sequestration. Hence, carbon dioxide sequestration in unmineable coals is a very attractive option, not only for environmental reasons, but also for possible economic benefits. Darcy flow through cleats is an important transport mechanism in coal. Cleat compression and permeability changes due to gas sorption desorption, changes of effective stress, and matrix swelling and shrinkage introduce a high level of complexity into the feasibility of a coal sequestration project. The economic effects of carbon dioxide-induced swelling on permeabilities and injectivities has received little (if any) detailed attention. Carbon dioxide and Methane have different swelling effects on coal. In this work, the Palmer-Mansoori model for coal shrinkage and permeability increases during primary Methane Production was re-written to also account for coal swelling caused by carbon dioxide sorption. The generalized model was added to PSU-COALCOMP, a dual porosity reservoir simulator for primary andmore » enhanced Coalbed Methane Production. A standard five-spot of vertical wells and representative coal properties for Appalachian coals were used.[1] Simulations and sensitivity analyses were performed with the modified simulator for nine different parameters, including coal seam and operational parameters and economic criteria. The coal properties and operating parameters that were varied included Young’s modulus, Poisson’s ratio, the cleat porosity, and the injection pressure. The economic variables included CH4 price, CO2 cost, CO2 credit, water disposal cost, and interest rate. Net present value analyses of the simulation results included profits due to Methane Production, and potential incentives for CO2 sequestered. This work shows that for some coal-property values, the compressibility and cleat porosity of coal may be more important than more purely economic criteria.« less

Shangzhi Meng - One of the best experts on this subject based on the ideXlab platform.

  • geological controls and Coalbed Methane Production potential evaluation a case study in liulin area eastern ordos basin china
    Journal of Natural Gas Science and Engineering, 2014
    Co-Authors: Yanjun Meng, Dazhen Tang, Shangzhi Meng
    Abstract:

    Abstract The Liulin area in the eastern Ordos Basin is one of the optimum areas for medium-rank Coalbed Methane (CBM) exploration and development in China. This work investigated the CBM geology and accumulation characteristics of No.4 coal in the Permian Shanxi Formation in the Liulin area based on data from 29 coal mining wells, 25 CBM wells and 14 coal samples. The results show that coal rank (medium volatile bituminous and low volatile bituminous) varies laterally, with the maximum vitrinite reflectance (Ro, max) ranges from 1.23 to 1.90%. Coals are dominated by vitrinite (47.9–90.5%); followed by inertinite (7.7–50.5%) and liptinite (0–0.6%). Minerals account for only a small proportion (0.4%–16.5%, avg. 4.7%). The results of well tests show that the coal permeability ranges from 0.02 to 3.44 mD, and the reservoir pressure ranges from 2.58 to 9.26 MPa. Most coal pores are less than 100 nm in diameter, and are favorable for gas adsorption but unfavorable for gas flow. Microfractures of coals are characterized by dendritic and step-shaped structures, relatively good connectivity, directionality and infrequent mineralization. The dominated types of microfractures are type C (less than 5 μm wide and more than 300 μm long) and type D (less than 5 μm wide and 300 μm long), with a large span of frequency ranging from 18 to 78 per 9 cm2. Methane adsorption isothermal measurements reveal that their maximum adsorption capacity (dry ash-free) vary from 21.36 to 26.38 m3/t. The in-place gas content is generally 4.93–14.96 m3/t. In combination with the geological information, the data reveals that structure properties, coal roof lithology and hydrogeology conditions have important influences on gas accumulation, preservation and enrichment. Furthermore, integrated geographical information system (GIS) and analytical hierarchy fuzzy prediction method (AHP) are used to evaluate the CBM Production potential in the Liulin area. The best prospective target area for CBM Production is forecasted to be located in the central slope belt (near southern Beilijiyuan and Yangjiayu areas) of the Liulin area.

  • multi branched horizontal wells for Coalbed Methane Production field performance and well structure analysis
    International Journal of Coal Geology, 2014
    Co-Authors: Jianhua Ren, Liang Zhang, Shaoran Ren, Jingde Lin, Shangzhi Meng, Guangjun Ren, Thomas Gentzis
    Abstract:

    Abstract Horizontal wells, such as multi-lateral and multi-branched horizontal wells (MBHWs) have been effectively used in the development of Coalbed Methane (CBM) fields, especially for coal beds with very low permeability and low compressive strength, in which the performance of conventional fracture-stimulated vertical wells is ineffective. In this study, the performance of MBHWs in the Liulin block of the Ordos Basin in central North China is analyzed and compared to that of hydraulically fractured vertical wells. The field pilot data show that the gas Production rate of most fractured vertical wells decreased rapidly after a short period of time, far below expectation, while the performance of MBHWs is satisfactory and relatively stable during 3 years of Production. A numerical simulation model was established based on the coal reservoir characteristics. The productivities of different well types are predicted and compared to the field data. The poor performance of the fractured vertical wells is thought to be caused by the early closure of the fractures and proppant embedded in the coal matrix or by a poor proppant delivery inside the fractures. The high and stable productivity of the MBHWs is attributed to their large drainage volume and to the stability of the wellbores. Simulation results show that the parameters of a MBHW, such as the branch angle, length, and spacing, can be optimized to maximize its productivity. Though the drilling cost of a MBHW is relatively high in comparison to vertical wells, its high and stable productivity can compensate for the drilling cost. Therefore, MBHWs are thought to be more appropriate than vertical wells for the successful exploitation of the CBM resource potential in the Liulin Block and surrounding area.