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Zhang Y, Zhang L, He J, Zhang H, Zhang X, Liu X. Fracability Evaluation Method of a Fractured-Vuggy Carbonate Reservoir in the Shunbei Block. ACS OMEGA 2023; 8:15810-15818. [PMID: 37151545 PMCID: PMC10157873 DOI: 10.1021/acsomega.3c02000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Accepted: 04/12/2023] [Indexed: 05/09/2023]
Abstract
The fracability of carbonate reservoirs is a key indicator for evaluating whether reservoirs can be effectively fractured. Taking the fractured-vuggy carbonate reservoir in the Shunbei block as an example, the microscopic characteristics and mechanical properties of this reservoir were analyzed. The test results showed that the core microstructure is relatively dense, the micropores and microfractures are developed, and the mineral composition is characterized by "high carbonate and few impurities". The compressive strength, Young's modulus, and Poisson's ratio of the rock increased with the increase in the confining pressure. Poisson's ratio is more sensitive to confining pressure than Young's modulus and shows the ductile transformation tendency from a low confining pressure to a high confining pressure. Considering the difficulty of forming a complex fracture network, we put forward a "fracture propagation factor" equation constructed with five main factors, including brittleness, fracture toughness, natural fracture, hole size, and horizontal stress difference, and then the fracture propagation factor of Yijianfang formation is calculated to be greater than 0.5. It is known that the Yijianfang formation has higher fracability. On this basis, combined with the construction parameters, a model for evaluating the fracability of a fractured-vuggy carbonate reservoir was established. The comprehensive fracability of four wells in the Shunbei block was calculated by the model. From the calculation results, the comprehensive fracability index of SHB43X was 0.5406 and greater than that of the other three wells, which has a high correlation with the production after fracturing.
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Affiliation(s)
- Yan Zhang
- Key
Laboratory of Marine Oil & Gas Reservoirs Production, Petroleum Exploration and Production Research Institute,
Sinopec, Beijing 102206, China
- College
of Petroleum Engineering of Yangtze University, Wuhan 430100, Hubei, China
| | - Lufeng Zhang
- Key
Laboratory of Marine Oil & Gas Reservoirs Production, Petroleum Exploration and Production Research Institute,
Sinopec, Beijing 102206, China
| | - Jiayuan He
- Key
Laboratory of Marine Oil & Gas Reservoirs Production, Petroleum Exploration and Production Research Institute,
Sinopec, Beijing 102206, China
| | - Hao Zhang
- College
of Petroleum Engineering of Yangtze University, Wuhan 430100, Hubei, China
| | - Ximin Zhang
- Drilling
Technology Research Institute, Sinopec Shengli
Oilfield Service Corporation, Deyang 618000, Sichuan, China
| | - Xiang Liu
- Petroleum
Engineering Technology Research Institute, Sinopec JiangHan Oilfield Corporation, Wuhan 433124, Hubei, China
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Du J, Guo G, Liu P, Xiong G, Chen P, Liu J, Chen X. Experimental Study on the Autogenic Acid Fluid System of a High-Temperature Carbonate Reservoir by Acid Fracturing. ACS OMEGA 2022; 7:12066-12075. [PMID: 35449980 PMCID: PMC9016866 DOI: 10.1021/acsomega.2c00259] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2022] [Accepted: 03/10/2022] [Indexed: 05/26/2023]
Abstract
As an important part of the acid fracturing process of carbonate reservoir, the performance of acid fracturing working fluid directly affects the stimulation effect of oil wells. In this paper, formaldehyde (agent A) and ammonium chloride (agent B) were used as the matrix. Several aldehydes with different volume ratios were prepared. The acid ratio with the highest acid yield was selected by the sodium hydroxide titration experiment. The results show that when the volume ratio of agent A to agent B is 1:1.3, the acid production capacity is the strongest. The pH values at several time points in the process of acid reaction were measured by a pen pH meter. The relationship curve between acid production capacity and time was obtained. The acid production capacity increased with time. It tends to be stable after a certain time. The experiment of acid rock reaction kinetics shows that the reaction rate between acid and rock decreases with the extension of time. The reaction time can reach 6 h. The reaction rate of autogenic acid under different temperatures and concentrations ranges from 6.61 × 10-7 to 9.49 × 10-7 mol/(s·cm2) within 6 h. Therefore, it indicates that the reaction time between autogenic acid and carbonate rock is long and the reaction rate is low. It is beneficial to improve the acid treatment effect of the carbonate reservoir. The conductivity experiments show that at different temperatures, with the increase of sealing pressure, the etching ability of autogenic acid decreases. The etching effect is better at 338 K. After etching, the permeability and conductivity of the rock slab of 5 MPa closure pressure are 227 D and 72.62 D·cm, respectively. To sum up, this autogenic acid is an effective working fluid in the acid fracturing process of the carbonate reservoir. It can obviously reduce the reaction rate of acid rock and has certain conductivity.
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Affiliation(s)
- Juan Du
- State
Key Laboratory of Oil & Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, Sichuan 610500, China
| | - Guixian Guo
- State
Key Laboratory of Oil & Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, Sichuan 610500, China
| | - Pingli Liu
- State
Key Laboratory of Oil & Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, Sichuan 610500, China
| | - Gang Xiong
- Research
Institute of Natural Gas Technology, PetroChina Southwest Oil &
Gasfield Company, Chengdu, Sichuan 610213, China
| | - Pengfei Chen
- Research
Institute of Natural Gas Technology, PetroChina Southwest Oil &
Gasfield Company, Chengdu, Sichuan 610213, China
| | - JinMing Liu
- State
Key Laboratory of Oil & Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, Sichuan 610500, China
| | - Xiang Chen
- State
Key Laboratory of Oil & Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, Sichuan 610500, China
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Zhang K, Liu Y, Sheng L, Li B, Chen T, Liu X, Yao E. Study on the Effect of Fracturing Fluid on the Structure and Mechanical Properties of Igneous Rock. ACS OMEGA 2022; 7:11903-11913. [PMID: 35449945 PMCID: PMC9016873 DOI: 10.1021/acsomega.1c07386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Accepted: 03/18/2022] [Indexed: 05/25/2023]
Abstract
Igneous rock oil and gas reservoirs have great development potential. Hydraulic fracturing is an important means for the development of these reservoirs. In the process of fracturing and increasing production, fracturing fluid is prone to a hydration reaction with clay minerals in igneous rock, and then, the structure and mechanical properties of the igneous rock are changed, affecting increased production. Therefore, it is necessary to establish a systematic water-rock reaction experiment method to understand the influence of fracturing fluid on the structure and mechanical properties of igneous rocks and to optimize the fracturing fluid system of igneous rock reservoirs. In this experiment, four solutions were used: slickwater, guar fracturing fluid, 2% KCl aqueous solution, and 4% KCl aqueous solution. Acoustic testing, porosity and permeability testing, XRD analysis, micro-CT scanning, and displacement experiments were performed. The influence of different fracturing fluids on the structure and mechanical properties of igneous rocks was studied. Igneous rock samples with a permeability of 0.05-0.1 mD and average porosity of 7-14% were used. The results show that all four liquid systems will reduce the permeability, Young's modulus, and brittleness index and increase the porosity and Poisson's ratio of the rock after fracturing. Among them, the permeability damage rate is as high as 37.37%, which may be related to the plugging of pores with solid residues in the gel breaking liquid; CT results show that there are microcracks in the rock, which increase over time, up to 13.54%. The brittleness index decreases. Among the fluids, the influence of slickwater on the rock brittleness index is the smallest, no more than 5%. Guar gum had the greatest effect on the Gel breaking liquid, up to 58%. One of the reasons for the increase in porosity is that adding a clay stabilizer composed of inorganic salts and organic cationic polymers to the slickwater fracturing fluid can effectively reduce the damage caused by the fracturing fluid to the rock during the fracturing process and can reduce the maximum by 50%. This paper can clarify the damage law of fracturing fluid systems to igneous rock reservoirs and provide the theoretical basis for the hydraulic fracturing of igneous rock reservoirs.
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Affiliation(s)
- Kun Zhang
- State
Key Laboratory of Oil and Gas Resources and Prospecting, China University of Petroleum at Beijing, Beijing 102249, China
- China
University of Petroleum Beijing Unconventional Natural Gas Institute, Beijing 102249, China
| | - Yuxuan Liu
- State
Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610500, China
| | - Lianqi Sheng
- State
Key Laboratory of Oil and Gas Resources and Prospecting, China University of Petroleum at Beijing, Beijing 102249, China
- China
University of Petroleum Beijing Unconventional Natural Gas Institute, Beijing 102249, China
| | - Bojun Li
- State
Key Laboratory of Oil and Gas Resources and Prospecting, China University of Petroleum at Beijing, Beijing 102249, China
- China
University of Petroleum Beijing Unconventional Natural Gas Institute, Beijing 102249, China
| | - Tianxiang Chen
- State
Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610500, China
| | - Xiongfei Liu
- State
Key Laboratory of Oil and Gas Resources and Prospecting, China University of Petroleum at Beijing, Beijing 102249, China
- China
University of Petroleum Beijing Unconventional Natural Gas Institute, Beijing 102249, China
| | - Erdong Yao
- State
Key Laboratory of Oil and Gas Resources and Prospecting, China University of Petroleum at Beijing, Beijing 102249, China
- China
University of Petroleum Beijing Unconventional Natural Gas Institute, Beijing 102249, China
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Lan L, Lu X, Zheng Y, Zhang G, Cheng Z. Synthesis and Performance of D230 Polyether Ammonium Salts Mixed with Cationic Gemini Surfactant as Clay Stabilizer for Water Injection Reservoirs. ARABIAN JOURNAL FOR SCIENCE AND ENGINEERING 2022. [DOI: 10.1007/s13369-022-06561-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Shibaev AV, Osiptsov AA, Philippova OE. Novel Trends in the Development of Surfactant-Based Hydraulic Fracturing Fluids: A Review. Gels 2021; 7:258. [PMID: 34940318 PMCID: PMC8701209 DOI: 10.3390/gels7040258] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Revised: 12/07/2021] [Accepted: 12/10/2021] [Indexed: 12/04/2022] Open
Abstract
Viscoelastic surfactants (VES) are amphiphilic molecules which self-assemble into long polymer-like aggregates-wormlike micelles. Such micellar chains form an entangled network, imparting high viscosity and viscoelasticity to aqueous solutions. VES are currently attracting great attention as the main components of clean hydraulic fracturing fluids used for enhanced oil recovery (EOR). Fracturing fluids consist of proppant particles suspended in a viscoelastic medium. They are pumped into a wellbore under high pressure to create fractures, through which the oil can flow into the well. Polymer gels have been used most often for fracturing operations; however, VES solutions are advantageous as they usually require no breakers other than reservoir hydrocarbons to be cleaned from the well. Many attempts have recently been made to improve the viscoelastic properties, temperature, and salt resistance of VES fluids to make them a cost-effective alternative to polymer gels. This review aims at describing the novel concepts and advancements in the fundamental science of VES-based fracturing fluids reported in the last few years, which have not yet been widely industrially implemented, but are significant for prospective future applications. Recent achievements, reviewed in this paper, include the use of oligomeric surfactants, surfactant mixtures, hybrid nanoparticle/VES, or polymer/VES fluids. The advantages and limitations of the different VES fluids are discussed. The fundamental reasons for the different ways of improvement of VES performance for fracturing are described.
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Affiliation(s)
| | - Andrei A. Osiptsov
- Skolkovo Institute of Science and Technology (Skoltech), 121205 Moscow, Russia;
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