Thermally enhanced shale gas recovery: microstructure characteristics of combusted shale

Cao, Yuanhao; Chen, Wei; Wang, Tengxi; Yang, Yuan

doi:10.1007/s12182-020-00428-y

Cited by 12 publications

(4 citation statements)

References 48 publications

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“…The new pore space of clay minerals is mainly generated by dehydration and morphological transformation under heat. In addition, Cao et al 66 observed the shale samples before and after being heated by scanning electron microscopy and found that a large number of flocculent clay minerals were heated to produce microcracks that can significantly improve shale connectivity. When carbonate rocks are decomposed by heat, the pore space of hundreds of nanometers reaches the peak value at 900 °C in Figure 9.…”

Section: ■ Discussionmentioning

confidence: 99%

Evolution of Shale Microstructure under in Situ Heat Treatment: Synchrotron Small-Angle X-ray Scattering

Zhang

Sun

et al. 2021

Energy Fuels

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Shale gas reservoirs are characterized by low porosity and low permeability which inhibits their large-scale commercial development. This has fueled research into the enhancement of gas recovery from shale reservoirs. In this study, a new method of increasing gas production by heating is proposed. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were used to analyze the mass loss curve and enthalpy change of shale during heating. The phase state changes of mineral composition during heating of organic-rich shale were also obtained. The pore distribution of shale samples during heat treatment was compared by using small-angle X-ray scattering technology, and the influence of heat on shale pore structure was analyzed. The results show that the thermal effect accelerates the increase in the number and size of micro-/nanopores in shale samples. This effectively improves the permeability of shale samples and induces the free migration of gas. In addition, the difference in the specific heat capacity of each mineral in shale samples will cause an inhomogeneous temperature distribution. Thermal stress causes the fracture of mineral crystals in shale, and the shrinkage between mineral particles causes the development of fractures in the shale matrix, which improves the shale gas reservoir permeability. Hence, in situ heat treatment is an efficient stimulation method for enhancing shale gas recovery.

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Section: ■ Discussionmentioning

confidence: 99%

Evolution of Shale Microstructure under in Situ Heat Treatment: Synchrotron Small-Angle X-ray Scattering

Zhang

Sun

et al. 2021

Energy Fuels

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“…Since adsorbed gas/oil makes up a significant fraction of the total gas/oil in shale compared with conventional gas/oil reservoirs, the quantity of gas desorbed from the matrix has a major impact on the final gas/oil production . Currently, some achievements have been made in the thermal recovery of shale gas/oil using hydraulic fracture heating technology. , However, complex temperature–sorption coupling behavior and its applications in assessing the effective thermal stimulation as a recovery strategy have not been adequately investigated .…”

Section: Enhanced Gas/oil Recovery Technologymentioning

confidence: 99%

Hydraulic Fracturing and Enhanced Recovery in Shale Reservoirs: Theoretical Analysis to Engineering Applications

et al. 2023

Energy Fuels

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Shale reservoirs are extensively exploited using hydraulic fracturing, which forms multiple cracks that connect with the existing natural fractures to create a continuous path for the gas stored in the kerogen to flow to the production well. Apart from the tedious nature of hydraulic fracturing, the mechanism of the storage and flow of gas is equally complex since multiple phases and scales are involved. An accurate understanding of hydraulic fracturing coupled with a strategy of analyzing the flow and overall recovery of gas is paramount to ensure efficient exploitation. In this work, a comprehensive review of the recent strategies used in analyzing the hydraulic fracturing, storage, flow, and recovery of gas is presented. To begin with, the experimental, analytical, and numerical approaches pertinent to hydraulic fracturing are deeply explored. Additionally, the flow of gas through the newly opened channels is accounted for by using a quadruple-domain approach where the mechanisms of flow in shale reservoirs at the nanoscale, microscale, mesoscale, and macroscale are considered. Furthermore, a strategy to capture the multiple phases, including gas, oil, and water, and recover both carbon dioxide and methane is explored through thermal and enhanced gas recovery approaches. This review provides a baseline for understanding how the hydraulic fracture evolves and propagates to create new channels that contribute to the flow of gas, how the gas flows through the created channels across the many scales of the shale reservoir, and how to improve recovery from shale reservoirs.

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“…Heavy oil resources are abundant in the world, and their reserves are no less than conventional crude oil resources [1][2][3][4][5][6]. China is rich in heavy oil resources, and a large number of heavy oil resources are concentrated in the Bohai Bay.…”

Section: Introductionmentioning

confidence: 99%

Cyclic Supercritical Multi-Thermal Fluid Stimulation Process: A Novel Improved-Oil-Recovery Technique for Offshore Heavy Oil Reservoir

et al. 2022

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Cyclic supercritical multi-thermal fluid stimulation (CSMTFS) is a novel technology that can efficiently recover heavy oil, while the heating effect, production and heat loss characteristics of CSMTFS have not been discussed. In this study, a physical simulation experiment of CSMTFS is conducted with a three-dimensional experimental system. The results of the study indicate that the whole process of CSMTFS can be divided into four stages, namely, the preheating stage, production increase stage, production stable stage and production decline stage, of which the production stable stage is the main oil production stage, and the production decline stage is the secondary oil production stage. In the first two stages of the CSMTFS process, there is no supercritical multi-thermal fluid chamber, and only a relatively small supercritical multi-thermal fluid chamber is formed in the last stage of the CSMTFS process. Out of the supercritical multi-thermal fluid chamber, supercritical water in the thermal fluids condensates to hot water and flows downward to heat the subjacent oil layer. At the same time, the non-condensate gas in the thermal fluids accumulates to the upper part of the oil layer and reduces heat loss. The analysis of heat loss shows that the heat loss rate gradually increases at first and then tends to be stable. Compared with conventional thermal fluid, the CSMTFS can more effectively reduce heat loss. The enthalpy value of supercritical multi-thermal fluid is significantly increased compared with that of multi-thermal fluid, which effectively solves the problem of insufficient heat carrying capacity of multi-thermal fluid. Overall, cyclic supercritical multi-thermal fluid stimulation can effectively solve the problems of conventional heavy oil thermal recovery technology in offshore heavy oil recovery; it is indeed a new improved-oil-recovery technique for offshore heavy oil. The findings of this study can help in better understanding the cyclic supercritical multi-thermal fluid stimulation process. This study is significant and helpful for application of CSMTFS technology in heavy oil recovery.

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Thermally enhanced shale gas recovery: microstructure characteristics of combusted shale

Cited by 12 publications

References 48 publications

Evolution of Shale Microstructure under in Situ Heat Treatment: Synchrotron Small-Angle X-ray Scattering

Evolution of Shale Microstructure under in Situ Heat Treatment: Synchrotron Small-Angle X-ray Scattering

Hydraulic Fracturing and Enhanced Recovery in Shale Reservoirs: Theoretical Analysis to Engineering Applications

Cyclic Supercritical Multi-Thermal Fluid Stimulation Process: A Novel Improved-Oil-Recovery Technique for Offshore Heavy Oil Reservoir

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