Raniganj Coalfield Research Articles

Laboratory Investigation to Assess Spontaneous Combustion/Fire During Extraction of Thick Coal Seam

Spontaneous combustion/fire and explosions occurring in the goaf area due to depillaring of thick coal seam (5–8 m) experiences significant loss to the mining industry. This ultimately causes destruction of natural resources and fatal accidents in India. Thus, it is threatening the safety of underground coal mines. This paper includes various laboratory studies to determine the cause of spontaneous combustion/fire during depillaring of panels in thick coal seams. The laboratory investigation comprises of proximate analysis, critical oxidation temperature study, differential scanning calorimetric analysis, fire ladder study, and goaf ignition temperature. The field investigation comprises of hygrometric survey to determine moisture loss and ventilation survey of the working seam to reveal that the goaf of the working panel is highly prone to spontaneous combustion/fire. The results of the above studies will help to develop suitable technique, i.e., partial stowing in goaf areas with the application of water mist spraying to prevent spontaneous combustion/fire during depillaring of thick coal seam. The above studies were carried out during depillaring panels (B2A and B2B) of a thick seam (5.4 m) at Khottadih Colliery, M/s Eastern Coalfields Limited of Raniganj coalfield of India.

A Geoinformatics Approach to Assess Land Use Dynamic and Landscape Fragmentation Due to Opencast Coal Mining in Raniganj Coalfield, India

A Geoinformatics Approach to Assess Land Use Dynamic and Landscape Fragmentation Due to Opencast Coal Mining in Raniganj Coalfield, India

Land use Dynamics and Landscape Patterns Assessment using Geoinformatics Techniques in Raniganj Coalfield, India

การศกษาครงนมวตถประสงคเพอประเมนมวลชวภาพเหนอพนดนของปาดบเขาตำอทยานแหงชาตดอยอนทนนท จงหวดเชยงใหม จากแปลงตวอยางถาวร 15 ha (n = 375) โดยอาศยสมการแอลโลเมตร และรปแบบความสมพนธของมวลชวภาพเหนอพนดนกบดชนพชพรรณตาง ๆ 4 ตวแปร คอ NDVI DVI RVI และ TNDVI จากภาพถายดาวเทยม Landsat 7 โดยวธ reduce major axis analysis ผลการศกษาพบวา มวลชวภาพเหนอพนดนของปาดบเขาตำ มคาเฉลยเทากบ380.9872 Mg/ha สวนรปแบบความสมพนธพบวา แนวโนมคามวลชวภาพเหนอพนดนมความสมพนธ กบคา NDVI, log(DVI), log(GVI) และ log(TNDVI) ในทางลบโดยมคาเทากบ b = -1.595955e-04**, b = -1.030396e-04**, b = -9.186332e-05**, b = -2.675757e-05** (P < 0.01) ตามลำดบ ซงความสมพนธดงกลาวสามารถนำไปประยกตสำหรบหาคาปรมาณการกกเกบคารบอนได และจะสงผลตอแนวทางหรอนโยบายในการอนรกษทรพยากรปาไมของไทยตอไปในอนาคตใหคงสภาพทสมบรณยงยนตอไป This study aimed to evaluate the above-ground biomass of lower montane forest in Doi Inthanon National Park Chiang Mai province from 15 ha permanent sample plots (n = 375) using the allometric equation. A causal relationship model among above ground biomass and vegetation index in 4 variables: NDVI DVI RVI TNDVI Landsat 7 satellite images by means reduce major axis analysis. The results showed that aboveground biomass in lower montane forest below with an average of 380.9872 Mg / ha. The relationship model that was likely the biomass above ground is correlated with the NDVI, log (DVI), log (GVI) and log (TNDVI) negatively by equal to b = -1.595955e-04**, b = -1.030396e-04**, b = -9.186332e-05**, b = -2.675757e-05** (P <0.01), respectively. Which such relationships can be applied for determining the amount of carbon storage and result can use for guidelines or policy to preserve the forest resources of Thailand in the future to maintain the integrity sustainable.

Species Diversity and Vegetation Structure of Coal Mine Generated Wasteland of Raniganj Coal Field, West Bengal, India

Species Diversity and Vegetation Structure of Coal Mine Generated Wasteland of Raniganj Coal Field, West Bengal, India

Influence of coal composition and maturity on methane storage capacity of coals of Raniganj Coalfield, India

Methane generation primarily depends on the quantity, type and structure of kerogens and is controlled by temperature to which the precursor material is subjected over the geologic time whereas the gas-in-place depends on the storage capacity and burial history. The Raniganj Coalfield of India hosts significant reserves of good quality coals of Permian age belonging to two formations, Barakar and Raniganj. The adsorption characteristics of the nine regional (R-I to R-IX) and three local seams from Raniganj Formation of south-western part of the coalfield is thoroughly investigated in the light of reflectance, petrography and chemical composition for their CBM potential. Ash (A), moisture (M), volatile matter (VM) and fixed carbon (FC) of these coals range within 12.8–37.3%, 1.1–4.0%, 31.7–51.1% (daf) and 48.9–68.3% (daf), respectively. Carbon (C) varies within the range 77.0–86.8% (dmmf) and reflectance (Rr) within 0.62–0.87%. The coals are high volatile gas prone orthohydrous bituminous type. Both C and Rr increase, and M and VM decrease with depth. Vitrinite ranges mostly within 64.5–85.5%, inertinite 4.8–24.1% and liptinite below 15%, on mineral matter free basis. Most of the samples fall in Type-III kerogen and few are transitional to Type-II and Type-III.Gas content of the samples lies between 3.08 and 14.96 cc/g, on daf basis and generally increases with depth. Langmuir volume (VL) for the coals varies between 17.4 and 29.8 cc/g (daf) and exhibits a moderately positive linear relationship with increase in depth (R2 = 0.58). Reflectance shows a strong linear positive relationship (R2 = 0.70) with Langmuir volume indicating the development of additional micropores with rank enhancement, thereby providing more surface area for adsorption. Gas content results are encouraging though the seams are considerably undersaturated. A very good correlation is observed for the combined effect of ash, moisture and carbon on volume adsorbed for the studied coals and can be used to predict adsorption capacity from compositional data.

Opencast Coal Mining Induced Degeneration of Streams: A GIS Based Study of the Raniganj Coalfield, India

Opencast Coal Mining Induced Degeneration of Streams: A GIS Based Study of the Raniganj Coalfield, India

Simulation of CO2 enhanced coalbed methane recovery in Jharia coalfields, India

Coalbed methane production in Jharia coalfield that lies in India's largest coal basin is underway since a few years now; however, no field-trial of CO2 enhanced coalbed methane (ECBM) recovery has been attempted till date. In this study, a detailed assessment of the techno-feasibility of long-term ECBM recovery for a coal block in Jharia coalfield was conducted using finite difference based numerical simulations. This was followed by a detailed comparative analysis with the performance of another key CBM producing block in Raniganj coal field (Vishal et al. [1]). During coupled CO2‒ECBM recovery, a significant enhancement in the amount of production of CH4 resulted due to the injection of CO2. Approximately, 220 Mm3 of CO2 was injected in the coal block and over 62 Mm3 of CH4 was recovered during the period of study. Upon comparison of the studied coal blocks, it can be well inferred that during the major dewatering stage, the rate of CO2 injection in Jharia block was lower as compared to that in the Raniganj coal block. The studied coal adsorb CO2 quickly and within a time span of nearly one year, peak CO2 matrix concentration near the injection well was achieved, indicating high adsorption potential for CO2.

Assessing the vulnerability of groundwater due to open pit coal mining using DRASTIC model: a case study of Phulbari Coal Mine, Bangladesh

Impacts on groundwater were carried out of an open pit coal mining area located in Phulbari under Dinajpur District in Bangladesh. The exploration of coal following the open pit method will influence the groundwater resources in and around the mine due to pumping of groundwater as well as precipitated water which will be accumulated in the floor of the open pit mine. Groundwater is the main source for agriculture and domestic use of that region. For qualitative analysis four water samples out of eight showed high contamination level (Cd > 3) ranging between 4.613–8.619 (6.6), two samples showed medium contamination level (Cd = 1–3) ranging between 2.171–2.785 and two samples showed the low contamination level (Cd 3) ranging between 155.868–1627.256. Before mining activities Cd ranged between 0.51–8.62 and HPI ranged between 2.04–4.42, but after mining activities Cd values are expected to be 155.86–1649.7 and HPI ranges between 22.53–204.58. The DRASTIC vulnerability index is computed for evaluation of three conditions (conventional DRASTIC, Modified DRASTICCdHPI for before and after mining activities). For conventional DRASTIC the vulnerability index is found ranging from 81–167 of which 31% area is high vulnerable. Before mining activities the vulnerability index was found ranging from 87–182 of which 30% area was high vulnerable but after mining activities the vulnerability index will be found ranging from 185–375 of which 24% area will be high vulnerable, 35% will be very high vulnerable and 41% will be extreme vulnerable. Selected eight heavy metals were analyzed using AAS. The prediction is done by following the data of Raniganj coal field, Maharashtra coal fired power plant in India and Poltegor coalmine, Poland. Two methods such as contamination index (Cd) and heavy metal pollution index (HPI) were used to evaluate the contamination levels. The software used for this study is Arcview 3.3 for the preparation of location map and DRASTIC vulnerability maps. The groundwater vulnerability assessment was done using DRASTIC model in GIS environment.

In-Situ Stress Measurement in Raniganj Coalfield and Its Applications in Mine Stability Analysis

The in situ stresses have significant effects on the stability of openings, support requirements, parting stability, pillar strength, etc. In order to analyze the stability of underground structures, the measurement of magnitude and direction of horizontal stress is necessary in addition to knowing other geomining parameters and rock properties. In this direction, this paper presents a systematic determination of in situ stresses in three mines of the southern Raniganj coalfield of India, using single sleeve fracturing technique. Based on the analysis of field test results, the gradients of major, minor and average horizontal stresses are established for the southern Raniganj coalfield. The determined in situ stress values are used in numerical modeling for stability evaluation of known case histories of parting between contiguous seams and pillars of this coalfield. The numerical modeling results analyzed in this paper validated that the in situ stresses determined in the Raniganj coalfield are acceptable for the stability analysis of coal pillars, parting and underground roadways.

Variations in hydro-chemical properties and source insights of coalbed methane produced water of Raniganj Coalfield, Jharkhand, India

The production of coalbed methane is increasing rapidly in Raniganj coalfield of India. The present statistics of methane gas production and produced water is about 1.7 mmscmd (million metric standard cubic meter per day) and 12160 m3/day respectively from 560 CBM wells. The major concerns are challenges related to CBM produced water treatment, it's handling, uses for various purposes and its proper disposal is yet to be resolved, considering physico-chemical parameters, socio-economic, environmental and techno-commercial aspects. In view of this, a detailed study of CBM produced water of Raniganj coalfield has been carried out to evaluate hydro-chemical variations, quantity, quality, related aquifer characteristics, options of treatment, suitable beneficial uses and disposal. The large amount of TDS is the major concern contributed by cations and anions like Na+, Ca2+ and HCO3−. The trace metal content obtained through Inductively Coupled Plasma Mass Spectrometry (ICPMS) analyses such as Fe2+, Mn2+, Zn2+, Sr2+ and Al3+ varies from 0.12 to 0.94, 0.002 to 0.651, 0.001 to 0.041, 0.005 to 0.801 and 0.002–0.092 mg/l respectively. Atomic absorption spectroscopy (AAS) was used for cations (Na+, K+, Mg2+ and Ca2+) distribution found ranged from 289 to 1136, 0.00 to 0.94, 0.18 to 1.82 and 10.2–21.2 mg/l respectively, whereas, anions (SO42−, F−, Cl−, NO3− and HCO3−) were determined using Ion Chromatography (IC), found varying from 0.14 to 1.62, 1.042 to 4.862, 114.42 to 565.21, 7.41 to 70.4 and 1923.4–3129.4 mg/l respectively. The CBM produced water is classified as Na+–K+–CO32-–HCO3- and Na+–HCO3- type attributed to different rock formations of aquifers and deeper coal seams. TDS and trace metals concentrations are controlled by depositional environment, local marine transgression occurred during the Sakmarian - Artinskian geological period and inherited from groundwater mineral interactions. The results of proposed model for quality parameter prediction signifies TDS content is observed to be low during the initial five years of production and gradually increases with time. The similar trend is shown by HCO3−, Na+, SO42−, F−, Cl− and NO3− signifying the rock interaction and alterations is the only source of minerals and ions. Initially, the shallow aquifer water having interaction with fresh water recharge dilutes the concentrations of different water quality parameters, but as production continues, the concentration of constituents directly controlled by formation rocks and may increase until it reaches the saturation point. The continuous drawdown of water from a large number of CBM wells changing the regional static hydrological balance including a drainage system and it may take long spells to recuperate its original levels. This study can be utilized in designing treatment processes, beneficial uses and exploring the new water resources in Raniganj coalfield.

Distribution of soil organic carbon and glomalin related soil protein in reclaimed coal mine-land chronosequence under tropical condition

The revegetation on mine spoiled lands has potential to improve the status of reclaimed mine-soil quality. However, to date the temporal dynamics of labile and stable fractions of soil organic carbon (SOC) and glomalin related soil protein (GRSP) have not been satisfactorily demonstrated. We investigated SOC and GRSP fractions including labile particulate OC (POC) and easily extractable GRSP (EE-GRSP) and stable non-particulate OC (NPOC) and difficulty extractable GRSP (DE-GRSP) along with other important soil properties in six reclaimed mine lands chronosequence (1 to 26 years old) and a reference forest site in Raniganj Coalfield, India. Our results demonstrated that the accumulation of SOC and GRSP significantly increased with increasing age of the sites, with greater extent of increment after 26 years were seen in labile POC (6.6×) and EE-GRSP (11.5×) compared to stable NPOC (1.8×) and DE-GRSP (6.2×). The higher contribution of GRSP-C in NPOC compared to TOC across the sites, indicate the proximate role of GRSP in accumulation and stabilization of SOC during the pedogenesis. The multivariate analysis revealed strong association among arbuscular mycorrhizal fungi (AMF) spore density, microbial biomass carbon, SOCs and GRSPs, suggesting the factors involved in SOC accumulation likely contributed to AMF proliferation and GRSP enrichment during the reclamation process. Moreover, strong correlation of GRSP and SOC with soil's bulk density, pH, total N and C/N ratio, suggest increasing GRSP and SOC content resulted in multi-level improvement in soil properties. Our results highlight the importance of using GRSP and SOC as indicator during mine land reclamation.

Geochemical contamination in the mine affected soil of Raniganj Coalfield – A river basin scale assessment

The study aimed to assess the heavy metals (K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, Zn, As, Pb, Sr, Zr) contamination in the soil of mine affected Singaran river basin and to analyse spatial variation in the contamination level considering 32 soil samples. Elemental analysis of soil samples has been performed through Energy Dispersive X-ray Analysis (EDX) to quantify the elemental concentration (mg kg−1). Heavy metal concentrations have been assessed through geo-accumulation index (Igeo) and enrichment factor (EF). Indices showed soils have moderate accumulation of most of the metals with moderate enrichment of Sr, Zr, Zn, Cu and Ni. Soil contamination level assessment has been carried out using indices like Contamination Factor (CF), degree of contamination (Cdeg), modified degree of contamination (mCdeg) and Pollution Load Index (PLI). CF shows moderate to considerable contamination by Sr, Zr, Ca, Cu, Mn, Zn and Ni. Mean indices values (mCdeg and PLI for the entire basin are 3.38 and 2.23 respectively) show low to moderate level of soil contamination. These indices result have been mapped and analysed in GIS platform to get spatial variation of pollution level. Opencast mines dominate middle catchment area and so is comparatively contaminated. Sample sites 11, 18 and 25 evidenced high values of all indices of pollution load. From the ecological standpoint Ecological Risk Factor (Er) and Potential Ecological Risk Index (RI) have been estimated to assess regional threat to native soil environment and it shows low ecological risk potential. Analysis shows that mine dominated soil of the entire Singaran basin is less contaminated in all respect but tends to the moderate contamination level at the mid-catchment area, especially by Sr, Zr, Zn, Cu and Ni.

Preliminary Understanding of CO2 Sequestration and Enhanced Methane Recovery in Raniganj Coalfield of India by Reservoir Simulation

India has a vast reserve of coal (∼ 7% of the world's total proved reserve) and is the third largest producer in the world. Almost 70% of the country's electrical power comes from the coal-fired thermal power plants. A few coalbed methane (CBM) projects have also commenced operations in the central and eastern parts of the country. However, CO2 sequestration especially in geological formations is still at conceptual stage in India. Raniganj coalfield, located in the eastern states of West Bengal of Jharkhand is a repository of large reserves of high-volatile bituminous coals, where both mining and CBM operations are present. A number of coal-based thermal power plants are also located in the area, making this one of the most suitable areas for starting a carbon capture and storage (CCS) pilot project.CCS in unmineable coal seams arguably has the advantage of commercial success through potential release of additional methane when injected CO2 adsorbs into the coal seams, the process known as enhanced coalbed methane (ECBM) recovery. However, a significant concern lies in the loss of injectivity due to reduction in permeability by coal matrix swelling with CO2 adsorption although this effect can be partially be offset with ‘huff and puff’ scheme of cyclic CO2 injection followed by extraction of the released methane.The paper discusses the results of a numerical simulation study carried out with GEM compositional reservoir simulator to evaluate the effects of uncertainties in various reservoir parameters on the overall volume of CO2 storage and additional methane recovery before planning a pilot project in the Raniganj coalfield. A 3-m thick seam at 600 m depth was considered for fluid flow simulation study. While some information on the reservoir setting was obtained through literature and personal communication with the CBM operators, the rest of the information was derived through laboratory studies. The reservoir parameters considered for the study are injection pressure, adsorption capacity, permeability, cleat porosity, sorption time, and initial gas saturation. A 160-acre drainage area with 5-spot vertical well pattern was considered with one central injector and four producers on four corners of the study area.The maximum allowable injection pressure was estimated to be ∼ 850 psi (5856kPa) at the reservoir setting. The injection pressure was varied from 300 psi (2067kPa) to 850 psi (5856kPa) in the simulation and 600 psi (4134kPa) was found to be the optimum injection pressure. A number of adsorption isotherms on coals of Raniganj coalfield were established in the laboratory. The variations in the adsorption parameters observed through the isotherms were considered as uncertainty in the storage capacities. Significant variations were observed due to the variation in adsorption isotherms both for CO2 storage and additional methane recovery. Fracture permeability was varied from 3 md to 40 md, which is the range of permeability observed in the coalfield. The results of simulation indicate a strong influence of permeability on the CO2 storage and ECBM recovery. In the absence of specific information on sorption time, it was theoretically varied from a very fast-desorbing coal (sorption time of 1 day) to an extremely slow-desorbing coal (sorption time 200 days). Since rate of desorption from the coal matrix and fracture permeability are rate-control parameters, for each sorption time a low and a high permeability situation were considered. Fluid flow simulation study shows that variation in sorption time has no significant effect for a low permeability situation while some marginal effect in high permeability situation. Cleat porosity was varied from 0.5% to 1.5%. Within this range of porosities, enhanced methane recovery varied from 70% to 85% relative to the primary recovery but the volume of stored CO2 did not vary significantly. Lastly, the initial gas saturation was varied from 70% to almost 100% and both the CO2 sequestered volume and additional methane recovery were found to increase substantially.

Source rock evaluation of the Gondwana coals in Raniganj coalfield, India

ABSTRACTPresent study perceived that samples have excellent hydrocarbon generation potential and total organic carbon (TOC) content. The pyrolysis temperature (Tmax) indicates that samples are in immature stage (<435°C) for hydrocarbon generation. The hydrogen index (HI) values show that the sample lies in a mixture of Type II–III and Type III kerogen. The plot of HI versus TOC implies that samples fall in fair oil source or gas/oil field. Field emission scanning electron microscopy (FE-SEM) and electron dispersive X-ray (EDX) study reveals that the different micro/macro pores and fracture system present mostly in organic substance. In situ gas content values are high enough to produce methane from coal beds.

Physicochemical study of coal for CBM extraction in Raniganj coal field, India

ABSTRACTThe main objective of this study is to assess the coal quality, petrographic composition, methane generation potential, maturity, and depositional environment of 12 samples from Raniganj coal field, India. The Rock-Eval pyrolysis and total organic carbon analysis suggest the presence of a mixture of Type III-II and Type III kerogen and have excellent gas generation potential. Petrographic and field emission scanning electron microscopy study shows the presence of vitrinite prosperous coal with different pores and fracture systems. The FTIR spectrum of samples suggests that the presence of aromatic H is helpful in gas generation. The Krevelen diagram shows that the samples lie in the Type-III kerogen.

Prospective evaluation of coal bed methane in Raniganj coal field, India

ABSTRACT The methane generation potential, methane sorption capacity, maturity, and petrographic study of 12 borehole samples from Raniganj coal field, India were determined. Petrographic, proximate, and ultimate analysis indicates that the all samples are matured. Adsorption isotherm and in-situ gas content analysis reveals that samples have excellent storage capacity (17.98–29.55 m3/t) and methane generation potential. Microscopic studies (FESEM and FTIR) of coal samples show well-developed pores, cleat system, and presence of aromatic H and aliphatic H. The simulation study shows that 17.68 Mm3 methane production can be possible in 10 years. The overall studies conclude that the Raniganj coal seams to have sufficient potential for coal bed methane extraction.

Energy analysis on Coalbed Methane (CBM) coupled power systems

Coalbed Methane (CBM) contains 97% of CH4 and very less amount of sulphur. Methane is a very high calorific value (≅55.7MJ/kg) gas as well as a greenhouse gas, which gets adsorbed on coal beds during coalification. Hence, capture of this CBM gas prior to coal mining not only prevents fire hazard but also the emission of greenhouse gas into the atmosphere. As the CBM gas is enriched in chemical energy, it is a promising source for power generation. In the present study, Raniganj (Jharkhand, India) Coal Field (RCF) properties are considered for CBM case study. A detailed energy analysis for the CBM and ECBM integrated carbon neutral power generating systems such as steam turbine, combined cycle (CC) and fuel cell systems is presented and the net thermal efficiency of each power plant with carbon capture and storage is estimated. High pressure coal seam is considered for combined cycle and solid oxide fuel cell (SOFC) cycle operation. Integration of power plant with CBM is studied for various coal seam operating pressures in the range of 3–1MPa and a high net thermal efficiency of 68.3% is found at 30bar with carbon capture and storage (CCS) for CBM integrated fuel cell cycle. In case of CBM integrated combined cycle and steam turbine system, a net thermal efficiency of 45% and 41% is estimated, respectively. An increase in 0.5% net thermal efficiency is calculated for ECBM case as compared to CBM under identical operating conditions of coal seam.

Water Quality Assessment of Pit-Lakes in Raniganj Coalfields Area, West Bengal, India

Water Quality Assessment of Pit-Lakes in Raniganj Coalfields Area, West Bengal, India

Mine closure plan and policy for open cast coal mine of raniganj coalfield, India

Mine closure plan and policy for open cast coal mine of raniganj coalfield, India

Prospects of shale gas exploitation in Lower Gondwana of Raniganj Coalfield (West Bengal), India

Geochemical analyses such as proximate, pyrolysis, TOC and FTIR, and other analyses like surface area, pore size, pore volume (using low–pressure N2 physisorption measurements) and SEM were performed on the shale samples derived from Early Permian Barakar and Late Permian Barren Measures formations of the Raniganj Coalfield, West Bengal. Rock–Eval pyrolysis and TOC data indicated that the heterogeneity of Barren Measures and Barakar shales is laterally varying, but in general, factors which support the occurrence of shale gas accumulations include a moderate to high TOC content (3.38–7.87 wt.%) with sufficient thermal maturity and type III–IV organic matters (kerogens). FTIR spectra indicate the presence of quartz and kaolinite with absorbance bandwidth between 1200–800 cm−1 and 3750–3400 cm−1, respectively. Abundance of quartz, as compared to clay, points towards the brittle characteristics of shales favourable for good fracability. Besides, mesopores and macropores are well–developed and the capacity of gas generation and adsorption are significant.&#x0D; On the basis of SEM, the pores are classified into four types– (i) inter–granular pores, (ii) dissolve pores, (iii) composite inter–granular pores, and (iv) hair line micro–fractures. The BET multipoint surface area varies from 8.104 to 16.937 m2/g and 17.376 to 29.675 m2/g for Barakar and Barren Measures shales, respectively. Size of the pores varies from 3.072 to 3.728 nm for the Barakar shales and 2.984 to 3.521 nm for the Barren Measures shales, as measured by BJH method. Overall, it is observed that mesopores, macropores, micro–fractures and micropores are adequate in the samples and the studied shales are having interconnected networks of natural cracks and pores system, which may control the storage and migration of shale gas in the reservoir.