scholarly journals Primary studies on the effect of coal bio-gasification in situ in the Qinshui basin

2021 ◽  
Author(s):  
Dong Xiao ◽  
Cong Zhang ◽  
Junyong Wu ◽  
Enyuan Wang ◽  
Hailun He ◽  
...  
Keyword(s):  
Coalbed Methane ◽  
Coal Gasification ◽  
Field Experiments ◽  
Methanogenic Bacteria ◽  
Gas Production ◽  
Coal Bed ◽  
Productivity Improvement ◽  
Qinshui Basin ◽  
In Situ Experiments

AbstractCoal bio-gasification is one in situ coal gasification technology that utilizes the digestion of organic components in coal by methanogenic bacteria. It is not only an effective technology to enhance the recoverable reserves of coalbed methane, but also an important technical method to promote clean coal utilization. Relevant laboratory researches have confirmed the technical feasibility of anthracite bio-gasification. However, in the complex environment of coal bed, whether in situ gas can be yield with methanogenic bacteria needs to be verified by in situ experiments. In this study, a vertical well and a horizontal well were used in Qinshui basin to perform field experiments to confirm the technical industrial feasibility. The concentration of Cl− ion and number changes of Methanogen spp. were used to trace nutrition diffusion. Gas production changes and coalbed biome evolution were used to analyze technical implementation results. The trace data and biome evolution identified that: (1) The development of Methanoculleus spp. has a significant positive correlation with culture medium diffusion; (2) the structure of coalbed microbial community was significantly changed with the injection of nutrition, and the newly constructed methanogenic community was more suitable for fermentation of coal; and (3) the evolution of dominant microflora has further enhanced bio-gasification of coal. Gas production data showed that the gasification of coal lasted 635 and 799 days and yielded 74,817 m3 and 251,754 m3 coalbed methane in Z-159 and Z-7H wells, respectively. One nutrition injection in coalbed achieved an average of 717 days of continuous gas production in experimental wells. Results confirmed that coalbed methane enhancement with bio-gasification of coal is a potential technology to achieve the productivity improvement of coalbed methane wells. And the findings of this study can help to further understand the mechanism of in situ coal bio-gasification and provide theoretical support for the development of biomining of coal.

scholarly journals Primary Studies on the Effect of Microbially Coalbed Methane Enhancement in Suit in the Qinshui Basin

2019 ◽  
Author(s):  
Dong Xiao ◽  
Cong Zhang ◽  
Enyuan Wang ◽  
Hailun He ◽  
Yidong Zhang ◽  
...  
Keyword(s):  
Coalbed Methane ◽  
Culture Medium ◽  
Gas Production ◽  
Coal Bed ◽  
Practical Application ◽  
Productivity Improvement ◽  
Qinshui Basin ◽  
Coal Biodegradation ◽  
Methane Enhancement ◽  
In Suit

AbstractMethods used to yield bio-methane with coal to increase coalbed methane reserves had researched, thus providing a means for improving gas drainage efficiency. One such method utilized to convert coal into gas involves coal biodegradation technology. In order to confirm the practical application of this technology, the experiments were conducted in wells, Z-159, Z-163, Z-167, and Z-7H, in the Qinshui Basin in China, and the duration of the experiments was 32 months. Cl- ion tracer, number changes of Methanogen sp., and coal bed biome evolution indicated that the culture medium diffused in the Z-159 and Z-7H wells. These wells resumed gas production separately. Gasification of coal lasted 635 and 799 days, and yielded 74817 m3 and 251754 m3 coalbed methane in Z-159 and Z-7H wells, respectively. Results demonstrate that coalbed methane enhancement with biogasification of coal is a potential technical to achieve the productivity improvement of coalbed methane wells.

Geological and Gas-Content Features of Coalbed Methane System in Qinshui Basin, Shanxi

2012 ◽  
Vol 170-173 ◽  
pp. 1187-1191
Author(s):  
Ya Hui Jia ◽  
Xiao Ping Xie ◽  
Ai Li Lu
Keyword(s):  
Coalbed Methane ◽  
Gas Content ◽  
Structural Deformation ◽  
Shanxi Province ◽  
Qinshui Basin ◽  
The North ◽  
North Part ◽  
Coalbed Methane Reservoir ◽  
High Yields

Colabed methane system is a natural system that consists of coal seams, coalbed methane in them and surrounding rocks. As an unconventional natural gas, reservoir and conservation of coalbed methane are different from those of conventional hydrocarbon. The Qinshui Basin, covering an area about 30,000sq.km in southeastern Shanxi Province, has abundant coalbed methane resources in the carboniferous Taiyuan formation and permian Shanxi formation, with an in-situ methane resource 3.3×1012 m3.In this study, the structural deformation and tectonic evolution of coalbed methane system in Qinshui basin were reported. Relationships between structural deformation and the formation of coalbed methane reservoir in Qinshui Basin were also discussed. The results show that Yangquan-Shouyang area in the north part of the basin and Tunliu-Xiangyuan area in the east are favorable for formation coalbed methane system. In contrast, Jincheng-Qinshui area in the south part of basin and the Qinyuan area in the middle of basin are favorable for both the formation of coalbed methane reservoirs and high yields as well.

Reverse Combustion Instabilities in Tar Sands and Coal

1980 ◽  
Vol 20 (04) ◽  
pp. 267-277 ◽  
Author(s):  
Robert D. Gunn ◽  
William B. Krantz
Keyword(s):  
Reaction Zone ◽  
Combustion Front ◽  
Stability Theory ◽  
Coal Gasification ◽  
Gas Production ◽  
Volatile Components ◽  
In Situ Combustion ◽  
Tar Sands ◽  
Vertical Well

Abstract A linear stability analysis shows that reverse combustion in coal and tar sands is only conditionally stable for mobility ratios less than one. However, high air-flow rates and gas generation at the combustion front can be stabilizing influences. For unstable operation, an estimate of the size of the reverse combustion channel may be obtained from the curve for the most highly amplified wave length. This provides a method for calculating the air flux, combustion front velocity, and rate of progress of the burn front. Recently the U.S. DOE Laramie Energy Technology Center (LETC) and Sandia Laboratories obtained experimental data about reverse combustion from a field test of in-situ coal gasification at Hanna, WY. These data show that 9.7 days were required for the development of a reverse combustion path 68 to 70 ft in length. The stability theory developed in this work predicts a length of 64 ft for this same 9.7-day period. In addition to quantitative predictions, stability theory provides an explanation of certain puzzling qualitative observations concerning reverse combustion. Introduction In-situ combustion is a potentially useful method for recovering fossil fuels from underground deposits. A number of in-situ combustion field tests have been conducted in oil reservoirs, tar sands, oil shale deposits, and coal seams. In-situ combustion can be classified into two broad categories: reverse combustion, in which the reaction front travels countercurrent to the flow of air, and forward combustion, in which the reaction zone travels in the same direction as the flow of air. Reverse combustion is especially important for coal and tar sands. During forward combustion, tars vaporized at the flame front in either coal or tar sands travel by convection into cooler regions ahead of the reaction zone where they condense and subsequently reduce the natural permeability of the fuel bed. In reverse combustion, vaporized tars or other high-molecular-weight compounds generated in the reaction zone travel toward the production well through a heated area already contacted by the high temperatures of the combustion front. As an added advantage, reverse combustion in tar sands substantially increases the relative permeability to gas. In lignite and subbituminous coal, drying and partial combustion typically increase the effective permeability to gas by four orders of magnitude. However, bituminous coal frequently swells on heating, and the net effect of reverse combustion on the permeability of swelling coals has not been investigated thoroughly. In coal and tar sands, reverse combustion is primarily a coking or carbonization process - i.e., the volatile components of the tar or coal are partially combusted while most of the carbon or coke is left unburned. For these reasons, reverse combustion represents an important part of some in-situ combustion methods currently being investigated for tar sands and coal. In the linked vertical well process for in-situ coal gasification, reverse combustion is used first to develop a high-permeability path between the production and air injection wells, while in the second stage of the process forward gasification or combustion is used as the major gas production method. Both industrial companies and government laboratories have investigated the linked vertical well process. For tar sands, the LETC is considering the use of reverse combustion as a preparatory mechanism similar to that used in coal.

scholarly journals Biogeochemistry and the associated redox signature of co-produced water from coalbed methane wells in the Shizhuangnan block in the southern Qinshui Basin, China

2020 ◽  
Vol 38 (4) ◽  
pp. 1034-1053
Author(s):  
Yang Li ◽  
Shuheng Tang ◽  
Songhang Zhang ◽  
Zhaodong Xi ◽  
Pengfei Wang
Keyword(s):  
Coalbed Methane ◽  
Produced Water ◽  
Dissolved Inorganic Carbon ◽  
Gas Production ◽  
Redox Conditions ◽  
Effective Parameters ◽  
Production Rates ◽  
Qinshui Basin ◽  
Southern Qinshui Basin ◽  
Biogeochemical Parameters

To meet the global energy demands, the exploitation of coalbed methane has received increasing attention. Biogeochemical parameters of co-produced water from coalbed methane wells were performed in the No. 3 coal seam in the Shizhuangnan block of the southern Qinshui Basin (China). These biogeochemical parameters were firstly utilized to assess coal reservoir environments and corresponding coalbed methane production. A high level of Na+ and HCO3– and deuterium drift were found to be accompanied by high gas production rates, but these parameters are unreliable to some extent. Dissolved inorganic carbon (DIC) isotopes δ13CDIC from water can be used to distinguish the environmental redox conditions. Positive δ13CDIC values within a reasonable range suggest reductive conditions suitable for methanogen metabolism and were accompanied by high gas production rates. SO42–, NO3– and related isotopes affected by various bacteria corresponding to various redox conditions are considered effective parameters to identify redox states and gas production rates. Importantly, the combination of δ13CDIC and SO42– can be used to evaluate gas production rates and predict potentially beneficial areas. The wells with moderate δ13CDIC and negligible SO42– represent appropriate reductive conditions, as observed in most high and intermediate production wells. Furthermore, the wells with highest δ13CDIC and negligible SO42– exhibit low production rates, as the most reductive environments were too strict to extend pressure drop funnels.

scholarly journals Fracturing curve and its corresponding gas productivity of coalbed methane wells in the Zhengzhuang block, southern Qinshui Basin, North China

2020 ◽  
Vol 38 (5) ◽  
pp. 1387-1408
Author(s):  
Yang Chen ◽  
Dameng Liu ◽  
Yidong Cai ◽  
Jingjie Yao
Keyword(s):  
Hydraulic Fracturing ◽  
Coalbed Methane ◽  
Continuous Production ◽  
Fracture Morphology ◽  
Geological Structure ◽  
In Situ Stress ◽  
Gas Production ◽  
Type Curves ◽  
Stable Type

Hydraulic fracturing has been widely used in low permeability coalbed methane reservoirs to enhance gas production. To better evaluate the hydraulic fracturing curve and its effect on gas productivity, geological and engineering data of 265 development coalbed methane wells and 14 appraisal coalbed methane wells in the Zhengzhuang block were investigated. Based on the regional geologic research and statistical analysis, the microseismic monitoring results, in-situ stress parameters, and gas productivity were synthetically evaluated. The results show that hydraulic fracturing curves can be divided into four types (descending type, stable type, wavy type, and ascending type) according to the fracturing pressure and fracture morphology, and the distributions of different type curves have direct relationship with geological structure. The vertical in-situ stress is greater than the closure stress in the Zhengzhuang block, but there is anomaly in the aggregation areas of the wavy and ascending fracturing curves, which is the main reason for the development of multi-directional propagated fractures. The fracture azimuth is consistent with the regional maximum principle in-situ stress direction (NE–NEE direction). Furthermore, the 265 fracturing curves indicate that the coalbed methane wells owned descending, and stable-type fracturing curves possibly have better fracturing effect considering the propagation pressure gradient (FP) and instantaneous shut-in pressure (PISI). Two fracturing-productivity patterns are summarized according to 61 continuous production wells with different fracturing type and their plane distribution, which indicates that the fracturing effect of different fracturing curve follows the pattern: descending type > stable type > wavy type > ascending type.

In-Situ Diffusion Experiment In Sparsely Fractured Granite

2004 ◽  
Vol 824 ◽  
Author(s):  
Peter Vilks ◽  
Neil H. Miller ◽  
Mark Jensen
Keyword(s):  
Field Experiments ◽  
Effective Diffusion ◽  
Rock Properties ◽  
Experimental Program ◽  
Diffusion Experiment ◽  
Stress Regime ◽  
In Situ Experiments ◽  
In Situ Diffusion ◽  
Conservative Values

AbstractThe in-situ diffusion experiment was conducted at AECL's Underground Research Laboratory (URL) to improve the understanding of diffusive solute transport in sparsely fractured or intact granitic rock (SFR). The experimental program used a comparative series of laboratory and in-situ field experiments to evaluate the ability of laboratory measurements to estimate in-situ rock properties and to explore issues surrounding the influence of stress relaxation, rock texture, porosity, pore geometry, and anisotropy on derived effective diffusion coefficients (De). In-situ experiments yielded iodide Debetween 1.4 × 10−13 and 1.1 × 10−12 m2/s. Unlike laboratory results, the in-situ De estimates did not exhibit correlation with sample depth or varied stress regime. Laboratory-derived measurements of De, porosity and permeability were found to systematically increase for samples removed from greater depths and higher stress regimes. Laboratory-derived iodide De values consistently trended higher than in-situ values by a factor of 1 to 15, except on the shallowest 240-m Level (σ1 ≍ 30 MPa) where differences were negligible. Laboratory-derived estimates of permeability were consistently higher than in-situ derived values by a factor of 2 to 100. This experimental program provides evidence that laboratory steady-state diffusion experiments are most likely to yield conservative values of De for simulation of diffusive mass transport in SFR.

Selection of Coal-Bed Methane Well Completion Method Based on Grey System Theory

2013 ◽  
Vol 295-298 ◽  
pp. 3171-3174
Author(s):  
Gang Yang ◽  
Zhi Ming Wang ◽  
Ru Jie Peng ◽  
Tian Chen ◽  
Zhong Xin Ren
Keyword(s):  
Coalbed Methane ◽  
Evaluation Method ◽  
Net Present Value ◽  
Gas Production ◽  
Grey System Theory ◽  
Coal Bed ◽  
Internal Rate Of Return ◽  
Grey System ◽  
Well Completion ◽  
Selection Of

Aim at the diversity of coalbed methane well completion methods, grey system is used to select completion method. Firstly, implement production prediction and economic evaluation. Then evaluate five indexes: cumulative gas production, net present value, dynamic payback period, internal rate of return and risk factor. The most appropriate completion method can be got. When apply this evaluation method to Sihe mining of Qinshui basin, results show that pinnate horizontal well is the most suitable completion method, followed by fractured vertical well.

scholarly journals Study on the Coalbed Methane Development under High In Situ Stress, Large Buried Depth, and Low Permeability Reservoir in the Libi Block, Qinshui Basin, China

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Jinkuang Huang ◽  
Shenggui Liu ◽  
Songlei Tang ◽  
Shixiong Shi ◽  
Chao Wang
Keyword(s):  
Coalbed Methane ◽  
Horizontal Wells ◽  
In Situ Stress ◽  
Low Permeability ◽  
Qinshui Basin ◽  
Hole Pressure ◽  
Bottom Hole ◽  
Single Well ◽  
Coal Reservoir

Coalbed methane (CBM) has been exploited in the deep area of the coal reservoir (>1000 m). The production of CBM vertical wells is low because of the high in situ stress, large buried depth, and low permeability of the coal reservoir. In this paper, efficient and advanced CBM development technology has been applied in the Libi Block of the Qinshui Basin. According to the characteristics of the coal reservoir in the Libi Block, the coiled tubing fracturing technology has been implemented in four cluster horizontal wells. Staged fracturing of horizontal wells can link more natural fracture networks. It could also expand the pressure drop range and control area of the single well. This fracturing technology has achieved good economic results in the Libi Block, with the maximum production of a single horizontal well being 25313 m3/d and the average single well production having increased by more than 60% from 5000 m3/d to 8000 m3/d. Based on the data regarding the bottom hole pressure, water production, and gas production, the production curves of four wells, namely, Z5P-01L, Z5P-02L, Z5P-03L, and Z5P-04L, were investigated. Furthermore, a production system with slow and stable depressurization was obtained. The bottom hole pressure drops too fast, which results in decreasing permeability and productivity. In this work, a special jet pump and an intelligent remote production control system for the CBM wells were developed; hence, a CBM production technology suitable for the Libi Block was established. The maximum release for the CBM well productivity was obtained, thus providing theoretical and technical support for CBM development with geological and engineering challenges.

A Permeation Theory for In-Situ Coal Gasification

1978 ◽  
Vol 18 (05) ◽  
pp. 300-314 ◽  
Author(s):  
R.D. Gunn ◽  
D.L. Whitman ◽  
D.D. Fischer
Keyword(s):  
Experimental Data ◽  
Field Test ◽  
Coal Gasification ◽  
Field Experiments ◽  
Field Tests ◽  
Injection Rate ◽  
Air Injection ◽  
Phase 2 ◽  
Heating Value

Abstract A permeation theory of in-situ coal gasification is developed, and a mathematical model is derived for the process. Predicted gas compositions, gas flow rates, and temperature profiles are in good agreement with field test data. For example, experimental gas compositions deviate no more than 3 to 4 mol% from calculated values. On the average, agreement is much better. The major purpose of the permeation theory is to provide a basis for quantitative understanding of in-situ coal gasification and to lead to important general conclusions concerning the nature of the process. The well instrumented Hanna 2, Phase 2 test was essential in providing needed Phase 2 test was essential in providing needed information to confirm the theoretical conclusions. This test was conducted near Hanna, WY, during 1976 and was the best instrumented and most successful held test ever conducted up to that time. PART 1: DEVELOPMENT OF THEORY PART 1: DEVELOPMENT OF THEORY The dilemma of rapidly decreasing reserves of natural gas in the U. S. and the need for a clean, easily transported fuel has spurred much interest in the production of gas from coal. One of the most promising methods of coal gasification was promising methods of coal gasification was demonstrated by field tests conducted for the last 5 years by the Laramie Energy Research Center at Hanna, Wy. In fact, Phase 2 of the Hanna 2 test (completed in May 1976) was perhaps the most successful in-situ coal gasification test ever conducted. It more complete description of this test is given later. The experimental data are presented in Part 2 to confirm the theory developed presented in Part 2 to confirm the theory developed in this section. Since May 1976, other successful field tests have been reported by the Alberta Research Council, Texas Utilities, and the Lawrence Livermore Laboratory. NEED FOR A THEORETICAL MODEL Before this study, no physical theory was available that successfully predicted field test data. Many of the most important features of underground coal gasification (UCG) were poorly understood or not understood at all. For example, the heating value of gas produced during the Hanna field tests was much higher than that reported for previous field experiments at other locations; the previous field experiments at other locations; the reasons for this anomaly were unknown. It was widely believed that the optimistic results from the Hanna field experiments might be peculiar or specific to the Hanna area. However, the development of a theory of UCG and successful field experiments with the linked, vertical well process at other locations now are proving this assumption false. The need for a theoretical understanding of UCG has become readily apparent. A more thorough interpretation of field test results required the development of a theoretical mathematical model for the process. In addition, design capability must be developed before UCG can become a commercial process. This capability is essential for carrying process. This capability is essential for carrying out economic studies and risk analyses as well as engineering design. The design method must determine many variables, such asgas composition,gas heating value,air injection rate requiredgas produced per unit volume of air injected,coal consumption rate,effect of coal composition,effect of coal bed thickness,effect of ash content,effect of moisture content,effect of varying pressure and air injection rate, andwell spacing and configuration. The theory developed in this study provides definite information concerning Items 1 through 10 as well as several items not listed. Item 11 can be determined by a two-dimensional extension of the methods described here. Not infrequently, design methods were developed empirically on the basis of experimental data. In fact, the Soviet Union has used this approach to UCG. A theoretical predictive method, however, is more desirable because much less costly field testing is required to validate the method. Once the method is fully validated, it can be used to predict UCG behavior even under operating predict UCG behavior even under operating conditions never tested previously. SPEJ P. 300

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