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4 pages, 173 KiB

Open AccessEditorial

New Advances in Oil, Gas, and Geothermal Reservoirs

by Daoyi Zhu

Energies 2023, 16(1), 477; https://doi.org/10.3390/en16010477 - 1 Jan 2023

Cited by 5 | Viewed by 1653

Abstract

The most significant geo-energy sources in the world today continue to be oil, gas, and geothermal reservoirs. To increase oil and gas reserves and production, new theories are constantly being developed in the laboratory and new technologies are being applied in the oilfield. [...] Read more.

The most significant geo-energy sources in the world today continue to be oil, gas, and geothermal reservoirs. To increase oil and gas reserves and production, new theories are constantly being developed in the laboratory and new technologies are being applied in the oilfield. This Special Issue compiles recent research focusing on cutting-edge ideas and technology in oil, gas, and geothermal reservoirs, covering the fields of well drilling, cementing, hydraulic fracturing, improved oil recovery, conformance control, and geothermal energy development. Full article

(This article belongs to the Special Issue New Advances in Oil, Gas and Geothermal Reservoirs)

Research

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21 pages, 7914 KiB

Open AccessArticle

Study on Unblocking and Permeability Enhancement Technology with Rotary Water Jet for Low Recharge Efficiency Wells in Sandstone Geothermal Reservoirs

by Chao Yu, Tian Tian, Chengyu Hui, Haochen Huang and Yiqun Zhang

Energies 2022, 15(24), 9407; https://doi.org/10.3390/en15249407 - 12 Dec 2022

Cited by 2 | Viewed by 1349

Abstract

In China, sandstone geothermal reservoirs are large in scale and widely distributed, but their exploitation is hindered by low recharge efficiency. In this paper, an unblocking and permeability enhancement technology using a rotary water jet for low recharge efficiency wells in sandstone geothermal [...] Read more.

In China, sandstone geothermal reservoirs are large in scale and widely distributed, but their exploitation is hindered by low recharge efficiency. In this paper, an unblocking and permeability enhancement technology using a rotary water jet for low recharge efficiency wells in sandstone geothermal reservoirs is proposed to solve this problem. This paper presents a series of studies about the proposed technology, including experiments, simulation and field application. Firstly, an experiment was carried out to verify the scale removal effect of a high-pressure water jet on the inner wall of the screen tube and its impact on sandstone. Secondly, the numerical models of the rotary jet flow field in the wellbore were established by ANSYS Fluent to study the influence of parameters. Finally, based on the simulation and experiment results, a rotary jet tool applicable to unblocking and descaling low-efficiency wells was designed, and a field application for low-efficiency wells in sandstone thermal reservoirs was conducted. The study results show that the unblocking and permeability enhancement technology using a rotary water jet is effective in removing the blockages and improving the permeability near the well. In conclusion, the presented technology can solve the problem of low efficiency during the reinjection of cooled thermal waters back into sandstone geothermal reservoirs and has great effectiveness in field application. Full article

(This article belongs to the Special Issue New Advances in Oil, Gas and Geothermal Reservoirs)

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20 pages, 9187 KiB

Open AccessArticle

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

by Jie Tian, Wende Yan, Zhilin Qi, Shiwen Huang, Yingzhong Yuan and Mingda Dong

Energies 2022, 15(23), 9189; https://doi.org/10.3390/en15239189 - 4 Dec 2022

Cited by 2 | Viewed by 1160

Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Special Issue New Advances in Oil, Gas and Geothermal Reservoirs)

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10 pages, 2360 KiB

Open AccessArticle

An NMR Investigation of the Influence of Cation Content in Polymer Ion Retarder on Hydration of Oil Well Cement

by Zhigang Qi, Yang Chen, Haibo Yang, Hui Gao, Chenhui Hu and Qing You

Energies 2022, 15(23), 8881; https://doi.org/10.3390/en15238881 - 24 Nov 2022

Cited by 2 | Viewed by 986

Abstract

Low field pulse nuclear magnetic resonance (LF-NMR) was used to analyze the effects of a polymeric ion retarder and the amount of acryloxyethyl trimethylammonium chloride (DMC) in the retarder on the distribution of T₂, thickening property, and strength of cement paste. [...] Read more.

Low field pulse nuclear magnetic resonance (LF-NMR) was used to analyze the effects of a polymeric ion retarder and the amount of acryloxyethyl trimethylammonium chloride (DMC) in the retarder on the distribution of T₂, thickening property, and strength of cement paste. The effect of pressure and temperature on the thickening curve was investigated, and the hydration products were analyzed using XRD. The result shows that the wrapped water of the precipitation is the main reaction aqueous phase of cement slurry in the hydration, with short T₂ time and a large relaxation peak area. The retarder weakens the van der Waals force and electrostatic adsorption force between the water and cement particles, reducing the hydration rate of cement particles. An appropriate increase in the cationic content of polymeric ion retarder can improve the early strength of cement slurry. Full article

(This article belongs to the Special Issue New Advances in Oil, Gas and Geothermal Reservoirs)

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26 pages, 12640 KiB

Open AccessArticle

A Study on Generation and Feasibility of Supercritical Multi-Thermal Fluid

by Xiaoxu Tang, Zhao Hua, Jian Zhang, Qiang Fu and Jie Tian

Energies 2022, 15(21), 8027; https://doi.org/10.3390/en15218027 - 28 Oct 2022

Cited by 3 | Viewed by 1022

Abstract

Supercritical multi-thermal fluid is an emerging and efficient heat carrier for thermal recovery of heavy oil, but the generation of supercritical multi-thermal fluid and its feasibility in thermal recovery are rarely discussed. In this paper, generation and flooding experiments of supercritical multi-thermal fluid [...] Read more.

Supercritical multi-thermal fluid is an emerging and efficient heat carrier for thermal recovery of heavy oil, but the generation of supercritical multi-thermal fluid and its feasibility in thermal recovery are rarely discussed. In this paper, generation and flooding experiments of supercritical multi-thermal fluid were carried out, respectively, for the generation and feasibility of supercritical multi-thermal fluid. During the experiment, the temperature and pressure in the reactor and sand-pack were monitored and recorded, the fluid generated by the reaction was analyzed by chromatography, and enthalpy of the reaction product and displacement efficiency were calculated, respectively. The experimental results showed that the change in temperature and pressure in the reactor could be roughly divided into three stages in the generation process of supercritical multi-thermal fluid. The higher the proportion of oil in the reactant, the higher the maximum temperature in the reactor. When the proportion of oil and water in the reactant was constant, the temperature rise in the reactor was basically the same under different initial temperature and pressure conditions. Compared with the initial temperature and pressure, the oil–water ratio of the reactants had a significant effect on the generated supercritical multi-thermal fluid. The higher the proportion of oil, the more gas that was generated in the supercritical multi-thermal fluid, and the lower the specific enthalpy of the thermal fluid. Under the same proportion of oil and water, the gas–water mass ratio of the supercritical multi-thermal fluid generated by the reaction of crude oil was lower, and the specific enthalpy was higher. Through this study, it was found that supercritical multi-thermal fluid with a low gas–water mass ratio had higher oil displacement efficiency, higher early oil recovery rate, a larger supercritical area formed in the oil layer, and later channeling. The results of this study show that the optimal gas–water mass ratio of supercritical multi-thermal fluid was about 1, under which the oil displacement efficiency and supercritical area in the oil layer reached the maximum. Correspondingly, the optimal proportion of oil in the reactant when generating supercritical multi-component thermal fluid was about 10%. In oilfield applications, because the gas–water ratio in supercritical multi-component thermal fluid has a significant impact on oil displacement efficiency, the optimization of supercritical multi-thermal fluid should not only consider the generation process but also consider the oil displacement effect of the thermal fluid. The findings of this study could improve our understanding of the characteristics of generating supercritical multi-thermal fluid and the feasibility of supercritical multi-thermal fluid generated under different conditions in the oil displacement process. This research is of great significance for field applications of supercritical multi-thermal fluid. Full article

(This article belongs to the Special Issue New Advances in Oil, Gas and Geothermal Reservoirs)

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14 pages, 6999 KiB

Open AccessArticle

Investigation on the Propagation Mechanisms of a Hydraulic Fracture in Glutenite Reservoirs Using DEM

by Jing Tang, Bingjie Liu and Guodong Zhang

Energies 2022, 15(20), 7709; https://doi.org/10.3390/en15207709 - 19 Oct 2022

Cited by 3 | Viewed by 992

Abstract

The geometry heterogeneity induced by embedded gravel can cause severe stress heterogeneity and strength heterogeneity in glutenite reservoirs, and subsequently affect the initiation and propagation of hydraulic fractures. Since the discrete element method (DEM) can accurately describe the inter-particle interactions, the macromechanical behavior [...] Read more.

The geometry heterogeneity induced by embedded gravel can cause severe stress heterogeneity and strength heterogeneity in glutenite reservoirs, and subsequently affect the initiation and propagation of hydraulic fractures. Since the discrete element method (DEM) can accurately describe the inter-particle interactions, the macromechanical behavior of glutenite specimen can be preciously represented by DEM. Therefore, the initiation and propagation mechanisms of hydraulic fractures were investigated using a coupling seepage-DEM approach, the terminal fracture morphologies of hydraulic fractures were determined, and the effects of stress differences, permeability, and gravel strength were studied. The results show that the initiation and propagation of hydraulic fractures are significantly influenced by embedded gravel. In addition, the stress heterogeneity and strength heterogeneity induced by the gravel embedded near the wellbore increase local initiation points, causing a complicated fracture network nearby. Moreover, due to the effect of local stress heterogeneity, gravel strength, and energy concentration near the fracture tip, four interactions of attraction, deflection, penetration, and termination between propagating fractures and encountering gravel were observed. Full article

(This article belongs to the Special Issue New Advances in Oil, Gas and Geothermal Reservoirs)

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16 pages, 10570 KiB

Open AccessArticle

Experimental Study of Proppant Placement Characteristics in Curving Fractures

by Zhiying Wu, Chunfang Wu and Linbo Zhou

Energies 2022, 15(19), 7169; https://doi.org/10.3390/en15197169 - 29 Sep 2022

Cited by 2 | Viewed by 1193

Abstract

Proppant placement in hydraulic fractures is crucial for avoiding fracture closure and maintaining a high conductivity pathway for oil and gas flow from the reservoir. The curving fracture is the primary fracture form in formation and affects proppant–fluid flow. This work experimentally examines [...] Read more.

Proppant placement in hydraulic fractures is crucial for avoiding fracture closure and maintaining a high conductivity pathway for oil and gas flow from the reservoir. The curving fracture is the primary fracture form in formation and affects proppant–fluid flow. This work experimentally examines proppant transport and placement in narrow curving channels. Four dimensionless numbers, including the bending angle, distance ratio, Reynolds number, and Shields number, are used to analyze particle placement in curving fractures. The results indicate that non-uniform proppant placement occurs in curving fractures due to the flow direction change and induces an irregular proppant dune. The dune height and covered area are lower than that in the straight fracture. The curving pathway hinders proppant distribution and leads to a dune closer to the inlet. When the distance increases between the inlet and curving section, a large depleted zone in the curving section will be formed and hinder oil and gas flowback. The covered area has negative linear correlations with the Reynolds number and Shields numbers. Four dimensionless parameters are used to develop a model to quantitatively predict the covered area of particle dune in curving fractures. Full article

(This article belongs to the Special Issue New Advances in Oil, Gas and Geothermal Reservoirs)

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14 pages, 4103 KiB

Open AccessArticle

Study on Apparent Permeability Model for Gas Transport in Shale Inorganic Nanopores

by Shuda Zhao, Hongji Liu, Enyuan Jiang, Nan Zhao, Chaohua Guo and Baojun Bai

Energies 2022, 15(17), 6301; https://doi.org/10.3390/en15176301 - 29 Aug 2022

Cited by 2 | Viewed by 1351

Abstract

Inorganic nanopores occurring in the shale matrix have strong hydrophilicity and irreducible water (IW) film can be formed on the inner surface of the pores making gas flow mechanisms in the pores more complex. In this paper, the existence of irreducible water (IW) [...] Read more.

Inorganic nanopores occurring in the shale matrix have strong hydrophilicity and irreducible water (IW) film can be formed on the inner surface of the pores making gas flow mechanisms in the pores more complex. In this paper, the existence of irreducible water (IW) in inorganic pores is considered, and, based on the Knudsen number (K

_{n}

) correction in shale pores, a shale gas apparent permeability model of inorganic nano-pores is established. The effect of the K

_{n}

correction on the apparent permeability, the ratio of flow with pore radius and the effect of IW on the apparent permeability are assessed. The main conclusions are as follows: (1) at low pressure (less than 10 MPa) and for medium pore size (pore radius range of 10 nm–60 nm), the effect of the K

_{n}

correction should be considered; (2) considering the effect of the K

_{n}

correction, bulk phase transport replaces surface diffusion more slowly; considering the existence of IW, bulk phase transport replaces surface diffusion more slowly; (3) with increase in pressure, the IW effect on gas apparent permeability decreases. Under low pressure, the IW, where pore size is small, promotes fluid flow, while the IW in the large pores hinders fluid flow. In conditions of ultra-high pressure, the IW promotes gas flow. Full article

(This article belongs to the Special Issue New Advances in Oil, Gas and Geothermal Reservoirs)

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10 pages, 2950 KiB

Open AccessArticle

Laboratory Evaluation of the Plugging Performance of an Inorganic Profile Control Agent for Thermal Oil Recovery

by Keyang Cheng, Yongjian Liu, Zhilin Qi, Jie Tian, Taotao Luo, Shaobin Hu and Jun Li

Energies 2022, 15(15), 5452; https://doi.org/10.3390/en15155452 - 27 Jul 2022

Cited by 3 | Viewed by 1135

Abstract

During the process of steam thermal recovery of heavy oil, steam channeling seriously affects the production and ultimate recovery. In this study, fly ash was used as the plugging agent, and then a series of plugging experiments based on the results of two-dimensional [...] Read more.

During the process of steam thermal recovery of heavy oil, steam channeling seriously affects the production and ultimate recovery. In this study, fly ash was used as the plugging agent, and then a series of plugging experiments based on the results of two-dimensional (2D) experiments were conducted to study the effect of plugging the steam breakthrough channels. The experimental results show that the inorganic particle plugging agent made from the fly ash had a good suspension stability, consolidation strength, and injection performance. Because of these characteristics, it was migrated farther in the formation with a high permeability than in the formation with a low permeability, and the plugging rate was greater than 99%. After steam injection, it had a good anti-flush ability and stable plugging performance in the formation. In terms of the oil displacement effect, oil recovery in the formation with a low permeability was effectively improved because of plugging. The results show that the inorganic particle plugging agent could effectively control the steam channeling and it improved the development effect of the heavy oil reservoir. Full article

(This article belongs to the Special Issue New Advances in Oil, Gas and Geothermal Reservoirs)

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16 pages, 4129 KiB

Open AccessArticle

Experimental Study of Temperature Effect on Methane Adsorption Dynamic and Isotherm

by Yongchun Zhang, Aiguo Hu, Pei Xiong, Hao Zhang and Zhonghua Liu

Energies 2022, 15(14), 5047; https://doi.org/10.3390/en15145047 - 11 Jul 2022

Cited by 3 | Viewed by 1172

Abstract

Knowing the methane adsorption dynamic is of great importance for evaluating shale gas reserves and predicting gas well production. Many experiments have been carried out to explore the influence of many aspects on the adsorption dynamic of methane on shale rock. However, the [...] Read more.

Knowing the methane adsorption dynamic is of great importance for evaluating shale gas reserves and predicting gas well production. Many experiments have been carried out to explore the influence of many aspects on the adsorption dynamic of methane on shale rock. However, the temperature effect on the adsorption dynamic as a potential enhanced shale gas recovery has not been well addressed in the publications. To explore the temperature effect on the adsorption dynamic of methane on gas shale rock, we conducted experimental measurement by using the volumetric method. We characterized the adsorption dynamic of methane on gas shale powders and found that the curves of pressure response at different pressure steps and temperatures all have the same tendency to decrease fast at first, then slowly in the middle and remain stable at last, indicating the methane molecules are mainly adsorbed in the initial stage. Methane adsorption dynamic and isotherm can be well fitted by the Bangham model and the Freundlich model, respectively. The constant z of the Bangham model first decreases and then increases with equilibrium pressure increasing at each temperature, and it decreases with temperature increasing at the same pressure. The adsorption rate, constant k of the Bangham model, is linearly positively correlated with the natural log of the equilibrium pressure, and it decreases with temperature increasing at the same pressure. Constant K and n of the Freundlich model all decrease with temperature increasing, indicating that low temperatures are favorable for methane adsorption on shale powders, and high temperatures can obviously reduce constant K and n of the Freundlich model. Finally, we calculated isosteric enthalpy and found that isosteric enthalpy is linearly positively correlated with the adsorption amount. These results will be profoundly meaningful for understanding the mechanism of methane adsorption dynamic on shale powders and provide a potential pathway to enhance shale gas recovery. Full article

(This article belongs to the Special Issue New Advances in Oil, Gas and Geothermal Reservoirs)

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15 pages, 2647 KiB

Open AccessArticle

Abnormal Phenomena and Mathematical Model of Fluid Imbibition in a Capillary Tube

by Wenquan Deng, Tianbo Liang, Shuai Yuan, Fujian Zhou and Junjian Li

Energies 2022, 15(14), 4994; https://doi.org/10.3390/en15144994 - 8 Jul 2022

Cited by 3 | Viewed by 1323

Abstract

At present, the imbibition behavior in tight rocks has been attracted increasing attention since spontaneous imbibition plays an important role in unconventional oil and gas development, such as increasing swept area and enhancing recovery rate. However, it is difficult to describe the imbibition [...] Read more.

At present, the imbibition behavior in tight rocks has been attracted increasing attention since spontaneous imbibition plays an important role in unconventional oil and gas development, such as increasing swept area and enhancing recovery rate. However, it is difficult to describe the imbibition behavior through imbibition experiment using tight rock core. To characterize the imbibition behavior, imbibition and drainage experiments were conducted among water, oil, and gas phases in a visible circular capillary tube. The whole imbibition process is monitored using a microfluidic platform equipped with a high frame rate camera. This study conducts two main imbibition experiments, namely liquid-displacing-air and water-displacing-oil experiments. The latter is a spontaneous imbibition that the lower-viscosity liquid displaces the higher-viscosity liquid. For the latter, the tendency of imbibition rate with time does not match with previous model. The experimental results indicate that it is unreasonable to take no account of the effect of accumulated liquid flowing out of the capillary tube on imbibition, especially in the imbibition experiments where the lower-viscosity liquid displaces the higher-viscosity liquid. A mathematical model is established by introducing an additional force to describe the imbibition behavior in capillary tube, and the model shows a good prediction effect on the tendency of imbibition rate with time. This study discovers and analyzes the effect of additional force on imbibition, and the analysis has significances to understand the imbibition behavior in tight rocks. Full article

(This article belongs to the Special Issue New Advances in Oil, Gas and Geothermal Reservoirs)

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21 pages, 11268 KiB

Open AccessArticle

Mechanism of Cuttings Removing at the Bottom Hole by Pulsed Jet

by Heqian Zhao, Huaizhong Shi, Zhongwei Huang, Zhenliang Chen, Ziang Gu and Fei Gao

Energies 2022, 15(9), 3329; https://doi.org/10.3390/en15093329 - 3 May 2022

Cited by 2 | Viewed by 1484

Abstract

Vibration drilling technology induced by hydraulic pulse can assist the bit in breaking rock at deep formation. Simultaneously, the pulsed jet generated by the hydraulic pulse promotes removal of the cuttings from the bottom hole. Nowadays, the cuttings removal mechanism of the pulsed [...] Read more.

Vibration drilling technology induced by hydraulic pulse can assist the bit in breaking rock at deep formation. Simultaneously, the pulsed jet generated by the hydraulic pulse promotes removal of the cuttings from the bottom hole. Nowadays, the cuttings removal mechanism of the pulsed jet is not clear, which causes cuttings to accumulate at the bottom hole and increases the risk of repeated cutting. In this paper, a pressure-flow rate fluctuation model is established to analyze the fluctuation characteristics of the pulsed jet at the bottom hole. Based on the model, the effects of displacement, well depth, drilling fluid viscosity, and flow area of the pulsed jet tool on the feature of instantaneous flow at the bottom hole are discussed. The results show that the pulsed jet causes flow rate and pressure to fluctuate at the bottom hole. When the displacement changes from 20 L/s to 40 L/s in a 2000 m well, the pulsed jet generates a flow rate fluctuation of 4–9 L/s and pressure fluctuation of 0.1–0.5 MPa at the bottom hole. With the flow area of the tool increasing from 2 cm² to 4 cm², the amplitude of flow rate fluctuation decreases by 72.5%, and the amplitude of pressure fluctuation decreases by more than 60%. Combined with the fluctuation feature of the flow field and the water jet attenuation law at the bottom hole, the force acting on the cuttings under the pulsed jet is derived. It is found that flow rate fluctuation improves the mechanical state of cuttings and is beneficial for cuttings tumbled off the bottom hole. This research provides theoretical guidance for pulsed jet cuttings cleaning at the bottom hole. Full article

(This article belongs to the Special Issue New Advances in Oil, Gas and Geothermal Reservoirs)

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