Status and Prospect of Drilling Fluid Loss and Lost Circulation Control Technology in Fractured Formation
Abstract
:1. Introduction
2. Drilling Fluid Loss and Lost Circulation Control Mechanism in Fractured Formation
2.1. Mechanism of Drilling Fluid Loss in Fractured Formation
2.2. Lost Circulation Control Mechanism in Fractured Formation
- (1)
- Stress cage theory
- (2)
- Fracture closure stress theory
- (3)
- Fracture extension stress theory
- (4)
- Chemical strengthening wellbore theory
3. Lost Circulation Material and Performance of Fractured Formation
3.1. Bridge Lost Circulation Materials and Properties
3.2. High-Water-Loss Lost Circulation Materials and Properties
3.3. Curable Lost Circulation Materials and Properties
3.4. Liquid Absorption Expansion Lost Circulation Materials and Properties
3.5. Flexible Gel Lost Circulation Materials and Properties
4. Evaluation Method of Drilling Fluid Loss and Lost Circulation Control
4.1. Evaluation Method of Drilling Fluid Loss in Fractured Formation
4.2. Evaluation Method of Pressure-Bearing Capacity in Fractured Formation
5. Development Prospect of Lost Circulation Control Technology
5.1. Strengthening the Mechanism of Lost Circulation Control in Fractured Formation
5.2. Research and Development of Adaptive and Efficient Lost Circulation Materials
5.3. Intelligent Plugging Equipment and Technology
6. Conclusions
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Acknowledgments
Conflicts of Interest
References
- Sun, J.; Bai, Y.; Cheng, R.; Lyu, K.; Liu, F.; Feng, J.; Lei, S.; Zhang, J.; Hao, H. Research progress and prospect of plugging technologies for fractured formation with severe lost circulation. Pet. Explor. Dev. 2021, 48, 732–743. [Google Scholar] [CrossRef]
- Bai, Y.; Zhang, Q.; Sun, J.; Lv, K.; Shang, X.; Liu, C.; Cheng, R.; Wang, F. Self-healing hydrogels and their action mechanism in oil–gas drilling and development engineering: A systematic review and prospect. J. Nat. Gas Sci. Eng. 2021, 96, 104250. [Google Scholar] [CrossRef]
- Jiang, G.; Sun, J.; He, Y.; Cui, K.; Dong, T.; Yang, L.; Yang, X.; Wang, X. Novel water-based drilling and completion fluid technology to improve wellbore quality during drilling and protect unconventional reservoirs. Engineering 2021, in press. [Google Scholar] [CrossRef]
- Cai, W.; Deng, J.; Feng, Y.; Lin, H.; Tanko, M.O.; Ma, C. Developing a geomechanics-modeling based method for lost circulation risk assessment: A case study in Bohai Bay, China. J. Pet. Sci. Eng. 2022, 210, 110045. [Google Scholar] [CrossRef]
- Bai, Y.; Liu, C.; Sun, J.; Shang, X.; Lv, K.; Zhu, Y.; Wang, F. High temperature resistant polymer gel as lost circulation material for fractured formation during drilling. Colloids Surfaces A Physicochem. Eng. Asp. 2022, 637, 128244. [Google Scholar] [CrossRef]
- She, J.; Zhang, H.; Kang, Y.; Feng, Y.; Zhong, Y.; Yang, B. Cusp catastrophe model for plugging pressure prediction of lost circulation control in fractured reservoirs. J. Pet. Sci. Eng. 2020, 186, 106705. [Google Scholar] [CrossRef]
- Murtaza, M.; Tariq, Z.; Zhou, X.; Al-Shehri, D.; Mahmoud, M.; Kamal, M.S. Okra as an environment-friendly fluid loss control additive for drilling fluids: Experimental & modeling studies. J. Pet. Sci. Eng. 2021, 204, 108743. [Google Scholar] [CrossRef]
- Krishna, S.; Ridha, S.; Vasant, P.; Ilyas, S.U.; Sophian, A. Conventional and intelligent models for detection and prediction of fluid loss events during drilling operations: A comprehensive review. J. Pet. Sci. Eng. 2020, 195, 107818. [Google Scholar] [CrossRef]
- Zhang, L.; Wang, Z.; Du, K.; Xiao, B.; Chen, W. A new analytical model of wellbore strengthening for fracture network loss of drilling fluid considering fracture roughness. J. Nat. Gas Sci. Eng. 2020, 77, 103093. [Google Scholar] [CrossRef]
- Zhang, X.; Deng, C.; Wang, D.; Wang, Z.; Teng, J.; Cao, J.; Xu, W.; Yang, F. Improving bonding quality of underwater friction stitch welds by selecting appropriate plug material and welding parameters and optimizing joint design. Mater. Des. 2016, 91, 398–410. [Google Scholar] [CrossRef]
- Zhou, H.; Wu, X.; Song, Z.; Zheng, B.; Zhang, K. A review of mechanism and adaptive materials of temporary plugging agent for chemical diverting fracturing. J. Pet. Sci. Eng. 2022, 212, 110256. [Google Scholar] [CrossRef]
- Xu, C.; Zhang, H.; Zhu, M.; Kang, Y.; Yan, X.; Zhang, J.; Bai, Y. Experimental study on the controlling factors of frictional coefficient for lost circulation control and formation damage prevention in deep fractured tight reservoir. Petroleum 2021, in press. [Google Scholar] [CrossRef]
- Liu, F.; Wang, X.; Li, X.; Dai, X.; Zhang, Z.; Wang, D.; Wang, Y.; Jiang, S. Poly(ionic liquids) based on β-cyclodextrin as fluid loss additive in water-based drilling fluids. J. Mol. Liq. 2022, 350, 118560. [Google Scholar] [CrossRef]
- Kamali, F.; Saboori, R.; Sabbaghi, S. Fe3O4-CMC nanocomposite performance evaluation as rheology modifier and fluid loss control characteristic additives in water-based drilling fluid. J. Pet. Sci. Eng. 2021, 205, 108912. [Google Scholar] [CrossRef]
- Gautam, S.; Guria, C.; Rajak, V.K. A state of the art review on the performance of high-pressure and high-temperature drilling fluids: Towards understanding the structure-property relationship of drilling fluid additives. J. Pet. Sci. Eng. 2022, 213, 110318. [Google Scholar] [CrossRef]
- Kang, Y.; Xu, C.; You, L.; Yu, H.; Zhang, B. Comprehensive evaluation of formation damage induced by working fluid loss in fractured tight gas reservoir. J. Nat. Gas Sci. Eng. 2014, 18, 353–359. [Google Scholar] [CrossRef]
- Yan, X.; Kang, Y.; You, L.; Xu, C.; Lin, C.; Zhang, J. Drill-in fluid loss mechanisms in brittle gas shale: A case study in the Longmaxi Formation, Sichuan Basin, China. J. Pet. Sci. Eng. 2019, 174, 394–405. [Google Scholar] [CrossRef]
- Maiti, M.; Bhaumik, A.K.; Mandal, A. Performance of water-based drilling fluids for deepwater and hydrate reservoirs: Designing and modelling studies. Pet. Sci. 2021, 18, 1709–1728. [Google Scholar] [CrossRef]
- Yang, M.; Chen, Y. Investigation of LCM soaking process on fracture plugging for fluid loss remediation and formation damage control. J. Nat. Gas Sci. Eng. 2020, 81, 103444. [Google Scholar] [CrossRef]
- Nascentes, C.L.; Murata, V.V.; Oliveira-Lopes, L.C. Mathematical modeling of solids-drilling fluid separation in shale shakers in oil fields: A state of art review. J. Pet. Sci. Eng. 2022, 208, 109270. [Google Scholar] [CrossRef]
- Kang, Y.; Xu, C.; Tang, L.; Li, S.; Li, D. Constructing a tough shield around the wellbore: Theory and method for lost-circulation control. Pet. Explor. Dev. 2014, 41, 520–527. [Google Scholar] [CrossRef]
- Xu, C.; Yan, X.; Kang, Y.; You, L.; You, Z.; Zhang, H.; Zhang, J. Friction coefficient: A significant parameter for lost circulation control and material selection in naturally fractured reservoir. Energy 2019, 174, 1012–1025. [Google Scholar] [CrossRef]
- You, L.; Tan, Q.; Kang, Y.; Zhang, X.; Xu, C.; Lin, C. Optimizing the particle size distribution of drill-in fluids based on fractal characteristics of porous media and solid particles. J. Pet. Sci. Eng. 2018, 171, 1223–1231. [Google Scholar] [CrossRef]
- Li, S.; Kang, Y.; Li, D.; You, L.; Xu, C. Modeling herschel-bulkely drilling fluid flowin a variable radial fracture. J. Porous Media 2014, 17, 239–254. [Google Scholar] [CrossRef]
- Dokhani, V.; Ma, Y.; Geng, T.; Li, Z.; Yu, M. Transient analysis of mud loss in fractured formations. J. Pet. Sci. Eng. 2020, 195, 107722. [Google Scholar] [CrossRef]
- Jia, L.; Chen, M.; Hou, B.; Sun, Z.; Jin, Y. Drilling fluid loss model and loss dynamic behavior in fractured formations. Pet. Explor. Dev. 2014, 41, 105–112. [Google Scholar] [CrossRef]
- Xu, C.; Yang, X.; Liu, C.; Kang, Y.; Bai, Y.; You, Z. Dynamic fracture width prediction for lost circulation control and formation damage prevention in ultra-deep fractured tight reservoir. Fuel 2022, 307, 121770. [Google Scholar] [CrossRef]
- Huang, F.; Kang, Y.; You, L.; Li, X.; You, Z. Massive fines detachment induced by moving gas-water interfaces during early stage two-phase flow in coalbed methane reservoirs. Fuel 2018, 222, 193–206. [Google Scholar] [CrossRef]
- Liang, H.; Ding, G.; Shen, X. Three-dimensional numerical solution and stress cage analysis of high conductive fractures pressure sealing. Petroleum 2020, in press. [Google Scholar] [CrossRef]
- Weijermars, R. Stress cages and fracture cages in stress trajectory models of wellbores: Implications for pressure management during drilling and hydraulic fracturing. J. Nat. Gas Sci. Eng. 2016, 36, 986–1003. [Google Scholar] [CrossRef]
- Lu, C.; Luo, Y.; Guo, J.; Huang, C.; Ma, L.; Luo, B.; Zhou, G.; Song, M. Numerical investigation of unpropped fracture closure process in shale based on 3D simulation of fracture surface. J. Pet. Sci. Eng. 2022, 208, 109299. [Google Scholar] [CrossRef]
- Dupriest, F.E. Fracture Closure Stress (FCS) and Lost Returns Practices. In Proceedings of the SPE/IADC Drilling Conference, Amsterdam, The Netherlands, 23–25 February 2005; p. SPE-92192-MS. [Google Scholar] [CrossRef]
- Li, J.; Qiu, Z.; Zhong, H.; Zhao, X.; Yang, Y.; Huang, W. Optimizing selection method of continuous particle size distribution for lost circulation by dynamic fracture width evaluation device. J. Pet. Sci. Eng. 2021, 200, 108304. [Google Scholar] [CrossRef]
- Li, J.; Qiu, Z.; Song, D.; Zhong, H.; Tang, Z. Numerical simulation of 3D fracture propagation in wellbore strengthening conditions. J. Pet. Sci. Eng. 2017, 156, 258–268. [Google Scholar] [CrossRef]
- Salehi, S.; Nygaard, R. Evaluation of New Drilling Approach for Widening Operational Window: Implications for Wellbore Strengthening. In Proceedings of the SPE Production and Operations Symposium, Oklahoma City, OK, USA, 27–29 March 2011; p. SPE-140753-MS. [Google Scholar]
- Mirabbasi, S.M.; Ameri, M.J.; Alsaba, M.; Karami, M.; Zargarbashi, A. The evolution of lost circulation prevention and mitigation based on wellbore strengthening theory: A review on experimental issues. J. Pet. Sci. Eng. 2022, 211, 110149. [Google Scholar] [CrossRef]
- Huang, X.; Sun, J.; Li, H.; Wang, R.; Lv, K.; Li, H. Fabrication of a Hydrophobic Hierarchical Surface on Shale Using Modified Nano-SiO2 for Strengthening the Wellbore Wall in Drilling Engineering. Engineering 2021, in press. [Google Scholar] [CrossRef]
- Li, J.; Qiu, Z.; Zhong, H.; Zhao, X.; Huang, W.; An, Z.; Yang, Y. The thermal and chemical effect on wellbore strengthening treatment in shale formation. J. Nat. Gas Sci. Eng. 2020, 74, 103102. [Google Scholar] [CrossRef]
- Van Oort, E.; Incedalip, O.; Vajargah, A.K. Thermal wellbore strengthening through managed temperature drilling—Part I: Thermal model and simulation. J. Nat. Gas Sci. Eng. 2018, 58, 275–284. [Google Scholar] [CrossRef]
- Lashkari, R.; Tabatabaei-Nezhad, S.A.; Husein, M.M. Shape memory polyurethane as a wellbore strengthening material. Powder Technol. 2022, 396, 291–304. [Google Scholar] [CrossRef]
- Xu, C.; Zhang, H.; Kang, Y.; Zhang, J.; Bai, Y.; Zhang, J.; You, Z. Physical plugging of lost circulation fractures at microscopic level. Fuel 2022, 317, 123477. [Google Scholar] [CrossRef]
- Li, J.; Qiu, Z.; Zhong, H.; Zhao, X.; Huang, W. Coupled CFD-DEM analysis of parameters on bridging in the fracture during lost circulation. J. Pet. Sci. Eng. 2020, 184, 106501. [Google Scholar] [CrossRef]
- Yan, X.; Kang, Y.; Xu, C.; Shang, X.; You, Z.; Zhang, J. Fracture plugging zone for lost circulation control in fractured reservoirs: Multiscale structure and structure characterization methods. Powder Technol. 2020, 370, 159–175. [Google Scholar] [CrossRef]
- Kang, Y.; Tan, Q.; You, L.; Zhang, X.; Xu, C.; Lin, C. Experimental investigation on size degradation of bridging material in drilling fluids. Powder Technol. 2019, 342, 54–66. [Google Scholar] [CrossRef]
- Zhu, J.; You, L.; Li, J.; Kang, Y.; Zhang, J.; Zhang, D.; Huang, C. Damage evaluation on oil-based drill-in fluids for ultra-deep fractured tight sandstone gas reservoirs. Nat. Gas Ind. B 2017, 4, 249–255. [Google Scholar] [CrossRef]
- Li, R.; Li, G.; Feng, Y.; Yang, X.; Teng, Y.; Hu, Y. Innovative experimental method for particle bridging behaviors in natural fractures. J. Nat. Gas Sci. Eng. 2022, 97, 104379. [Google Scholar] [CrossRef]
- Jia, H.; Niu, C.-C.; Yang, X.-Y. Improved understanding nanocomposite gel working mechanisms: From laboratory investigation to wellbore plugging application. J. Pet. Sci. Eng. 2020, 191, 107214. [Google Scholar] [CrossRef]
- Gang, W.; Honghai, F.; Jie, F.; Wanjun, L.; Yu, Y.; Xiangji, K.; Yingying, L.; Jitong, L.; Chenchao, L.; Haijun, Y. Performance and application of high-strength water-swellable material for reducing lost circulation under high temperature. J. Pet. Sci. Eng. 2020, 189, 106957. [Google Scholar] [CrossRef]
- Liang, Y.; Jin, C.; Wang, Z.; Guo, Y.; Shi, S.; Fan, L.; Song, D.; Li, N.; Zhang, Y.; Wang, J.; et al. Insights on the penetration and migration of chemically cross-linked systems in porous media. J. Pet. Sci. Eng. 2022, 213, 110374. [Google Scholar] [CrossRef]
- Cui, K.-X.; Jiang, G.-C.; Yang, L.-L.; Deng, Z.-Q.; Zhou, L. Preparation and properties of magnesium oxysulfate cement and its application as lost circulation materials. Pet. Sci. 2021, 18, 1492–1506. [Google Scholar] [CrossRef]
- Xu, B.; Yuan, B.; Guo, J.; Xie, Y.; Lei, B. Novel technology to reduce risk lost circulation and improve cementing quality using managed pressure cementing for narrow safety pressure window wells in Sichuan Basin. J. Pet. Sci. Eng. 2019, 180, 707–715. [Google Scholar] [CrossRef]
- Tian, L.; Bu, Y.; Liu, H.; Guo, S. Study on the penetration of strengthening material for deep-water weakly consolidated shallow formation. J. Pet. Sci. Eng. 2022, 210, 109862. [Google Scholar] [CrossRef]
- Li, S.; Ma, C.; Liu, R.; Chen, M.; Yan, J.; Wang, Z.; Duan, S.; Zhang, H. Super-absorbent swellable polymer as grouting material for treatment of karst water inrush. Int. J. Min. Sci. Technol. 2021, 31, 753–763. [Google Scholar] [CrossRef]
- Jing, Y.; Wang, P.; Yang, Q.; Wang, Q. Study on feasibility and mechanism of the subcritical oxidation of waste drilling mud. Colloids Surfaces A Physicochem. Eng. Asp. 2022, 640, 128424. [Google Scholar] [CrossRef]
- Huang, B.; Zhang, W.; Zhou, Q.; Fu, C.; He, S. Preparation and Experimental Study of a Low-Initial-Viscosity Gel Plugging Agent. ACS Omega 2020, 5, 15715–15727. [Google Scholar] [CrossRef]
- Zhai, K.; Yi, H.; Liu, Y.; Geng, Y.; Fan, S.; Zhu, D. Experimental Evaluation of the Shielded Temporary Plugging System Composed of Calcium Carbonate and Acid-Soluble Preformed Particle Gels (ASPPG) for Petroleum Drilling. Energy Fuels 2020, 34, 14023–14033. [Google Scholar] [CrossRef]
- Zhu, D.; Xu, Z.; Sun, R.; Fang, X.; Gao, D.; Jia, X.; Hu, J.; Weng, J. Laboratory evaluation on temporary plugging performance of degradable preformed particle gels (DPPGs). Fuel 2021, 289, 119743. [Google Scholar] [CrossRef]
- Yu, B.; Zhao, S.; Long, Y.; Bai, B.; Schuman, T. Comprehensive evaluation of a high-temperature resistant re-crosslinkable preformed particle gel for water management. Fuel 2022, 309, 122086. [Google Scholar] [CrossRef]
- Niu, L.; Lu, X.; Xiong, C.; Tang, X.; Wu, X.; Jia, X.; Zhang, S. Experimental study on gelling property and plugging effect of inorganic gel system (OMGL). Pet. Explor. Dev. 2013, 40, 780–784. [Google Scholar] [CrossRef]
- Bai, B.; Leng, J.; Wei, M. A comprehensive review of in-situ polymer gel simulation for conformance control. Pet. Sci. 2022, 19, 189–202. [Google Scholar] [CrossRef]
- Jia, H.; Yang, X. Environmental and strength-enhanced nanosilica-based composite gel for well temporary plugging in high-temperature reservoirs. Asia-Pacific J. Chem. Eng. 2019, 14, e2270. [Google Scholar] [CrossRef] [Green Version]
- Al-Shargabi, M.; Davoodi, S.; Wood, D.A.; Al-Musai, A.; Rukavishnikov, V.S.; Minaev, K.M. Nanoparticle applications as beneficial oil and gas drilling fluid additives: A review. J. Mol. Liq. 2022, 352, 118725. [Google Scholar] [CrossRef]
- Lin, C.; Taleghani, A.D.; Kang, Y.; Xu, C. A coupled CFD-DEM numerical simulation of formation and evolution of sealing zones. J. Pet. Sci. Eng. 2022, 208, 109765. [Google Scholar] [CrossRef]
- Xu, C.; Zhang, J.; Kang, Y.; Xu, F.; Lin, C.; Yan, X.; Jing, H.; Shang, X. Structural formation and evolution mechanisms of fracture plugging zone. Pet. Explor. Dev. 2021, 48, 232–242. [Google Scholar] [CrossRef]
- Zhang, D.; Jin, J.; Li, D.; Kang, Y.; Xu, J.; Wang, W. Numerical 3D-Simulation of Dynamic Natural Fracture Width for Lost Circulation Control in Deep Fractured Tight Reservoir. In Proceedings of the 54th U.S. Rock Mechanics/Geomechanics Symposium, physical event cancelled, June 2020; p. ARMA-2020-1265. [Google Scholar] [CrossRef]
- Peng, X.; Rao, X.; Zhao, H.; Xu, Y.; Zhong, X.; Zhan, W.; Huang, L. A proxy model to predict reservoir dynamic pressure profile of fracture network based on deep convolutional generative adversarial networks (DCGAN). J. Pet. Sci. Eng. 2022, 208, 109577. [Google Scholar] [CrossRef]
- Schwarzer, M.; Rogan, B.; Ruan, Y.; Song, Z.; Lee, D.Y.; Percus, A.G.; Chau, V.; Moore, B.A.; Rougier, E.; Viswanathan, H.S.; et al. Learning to fail: Predicting fracture evolution in brittle material models using recurrent graph convolutional neural networks. Comput. Mater. Sci. 2019, 162, 322–332. [Google Scholar] [CrossRef] [Green Version]
- Xu, C.-Y.; Kang, Y.-L.; You, L.-J.; Li, S.; Chen, F. High-Strength, High-Stability Pill System to Prevent Lost Circulation. In Proceedings of the International Petroleum Technology Conference, Beijing, China, 26–28 March 2013; p. IPTC-17127-MS. [Google Scholar] [CrossRef]
- Sui, W.; Tian, Y.; Zheng, Y.; Dong, K. Modeling Temporary Plugging Agent Transport in the Wellbore and Fracture with a Coupled Computational Fluid Dynamics–Discrete Element Method Approach. Energy Fuels 2021, 35, 1422–1432. [Google Scholar] [CrossRef]
- Bai, Y.; Shang, X.; Wang, Z.; Zhao, X. Experimental study of low molecular weight polymer/nanoparticle dispersed gel for water plugging in fractures. Colloids Surfaces A Physicochem. Eng. Asp. 2018, 551, 95–107. [Google Scholar] [CrossRef]
- Jiang, H.; Liu, G.; Li, J.; Zhang, T.; Wang, C. A realtime drilling risks monitoring method integrating wellbore hydraulics model and streaming-data-driven model parameter inversion algorithm. J. Nat. Gas Sci. Eng. 2021, 85, 103702. [Google Scholar] [CrossRef]
- Jia, H.; Pu, W.-F.; Zhao, J.-Z.; Liao, R. Experimental Investigation of the Novel Phenol−Formaldehyde Cross-Linking HPAM Gel System: Based on the Secondary Cross-Linking Method of Organic Cross-Linkers and Its Gelation Performance Study after Flowing through Porous Media. Energy Fuels 2011, 25, 727–736. [Google Scholar] [CrossRef]
- Zhu, Z.-X.; Li, L.; Liu, J.-W.; Chen, J.; Xu, Z.-Z.; Wu, Y.-N.; Dai, C.-L. Probing the effect of Young's modulus on the plugging performance of micro-nano-scale dispersed particle gels. Pet. Sci. 2021, in press. [Google Scholar] [CrossRef]
- Xu, C.; Yan, X.; Kang, Y.; You, L.; Zhang, J. Structural failure mechanism and strengthening method of fracture plugging zone for lost circulation control in deep naturally fractured reservoirs. Pet. Explor. Dev. 2020, 47, 430–440. [Google Scholar] [CrossRef]
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. |
© 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
Share and Cite
Yang, J.; Sun, J.; Bai, Y.; Lv, K.; Zhang, G.; Li, Y. Status and Prospect of Drilling Fluid Loss and Lost Circulation Control Technology in Fractured Formation. Gels 2022, 8, 260. https://doi.org/10.3390/gels8050260
Yang J, Sun J, Bai Y, Lv K, Zhang G, Li Y. Status and Prospect of Drilling Fluid Loss and Lost Circulation Control Technology in Fractured Formation. Gels. 2022; 8(5):260. https://doi.org/10.3390/gels8050260
Chicago/Turabian StyleYang, Jingbin, Jinsheng Sun, Yingrui Bai, Kaihe Lv, Guodong Zhang, and Yuhong Li. 2022. "Status and Prospect of Drilling Fluid Loss and Lost Circulation Control Technology in Fractured Formation" Gels 8, no. 5: 260. https://doi.org/10.3390/gels8050260