A Method for Evaluating Coalbed Methane Reservoir Productivity Considering Drilling Fluid Damage
In the process of coalbed methane development, drilling fluid and fracturing fluid cannot achieve absolute compatibility with formation. The incompatibility between the working fluid and reservoir will lead to the intrusion of working fluid into the reservoir and cause reservoir pollution. This is a...
| Main Authors: | , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2024-04-01
|
| Series: | Energies |
| Subjects: | |
| Online Access: | https://www.mdpi.com/1996-1073/17/7/1686 |
| _version_ | 1797212673076625408 |
|---|---|
| author | Chen Li Lichun Sun Zhigang Zhao Jian Zhang Yong Li Yanjun Meng Lei Wang |
| author_facet | Chen Li Lichun Sun Zhigang Zhao Jian Zhang Yong Li Yanjun Meng Lei Wang |
| author_sort | Chen Li |
| collection | DOAJ |
| description | In the process of coalbed methane development, drilling fluid and fracturing fluid cannot achieve absolute compatibility with formation. The incompatibility between the working fluid and reservoir will lead to the intrusion of working fluid into the reservoir and cause reservoir pollution. This is a very common phenomenon. There is a large amount of pulverized coal in the coal seam, and the intrusion of working liquid will be combined with the pulverized coal to form cement to block the seepage space in the reservoir. Since pressure relief and fracturing fluid backflow will be performed at the first time after fracturing, the intrusion range of the working fluid is small, generally reaching 10 m to 50 m. Compared with a conventional gas reservoir or shale gas reservoir, the working fluid loss during CBM development will seriously affect the subsequent production project and even make the gas well lose production capacity. On the other hand, in order to avoid this phenomenon, measures such as acidification or volumetric fracturing are sometimes used to improve the seepage environment near the well and near the fracture. The purpose of this study is to quantitatively evaluate the impacts of working fluid filtration and reservoir reconstruction on production. In this study, a single well productivity evaluation model and sensitivity analysis method considering drilling fluid filtration loss, fracturing fluid filtration loss, reservoir reconstruction and other processes is proposed. The formation mechanism of fluid loss during drilling and fracturing is described, and the productivity evaluation model considering fluid loss is combined with the Langmuir isothermal adsorption equation, steady-state diffusion law, Darcy’s seepage law and Duhamel convolution formation. Combined with the distribution of actual gas reservoir flow characteristics, the sensitivity of single well productivity to gas reservoir porosity, gas reservoir permeability, coal seam adsorption coefficient, working fluid filtration loss and reservoir reconstruction measures are analyzed. Through the analysis and fitting of the actual production data on site, the relationship curve can better fit the field production data, and the evaluation results are in line with the drilling and fracturing conditions at that time and the subsequent production conditions, with small errors. The obtained method is suitable for predicting the productivity of fractured vertical wells in different working conditions and provides a basis for the development and productivity prediction of CBM reservoirs in China and in international cooperation. |
| first_indexed | 2024-04-24T10:46:07Z |
| format | Article |
| id | doaj.art-ecc88d42a6be4729815919def45b93c4 |
| institution | Directory Open Access Journal |
| issn | 1996-1073 |
| language | English |
| last_indexed | 2024-04-24T10:46:07Z |
| publishDate | 2024-04-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Energies |
| spelling | doaj.art-ecc88d42a6be4729815919def45b93c42024-04-12T13:18:05ZengMDPI AGEnergies1996-10732024-04-01177168610.3390/en17071686A Method for Evaluating Coalbed Methane Reservoir Productivity Considering Drilling Fluid DamageChen Li0Lichun Sun1Zhigang Zhao2Jian Zhang3Yong Li4Yanjun Meng5Lei Wang6CNOOC Research Institute Ltd., CNOOC Building, Yard 6, Taiyanggong South Street, Chaoyang District, Beijing 100028, ChinaCNOOC Research Institute Ltd., CNOOC Building, Yard 6, Taiyanggong South Street, Chaoyang District, Beijing 100028, ChinaCNOOC Research Institute Ltd., CNOOC Building, Yard 6, Taiyanggong South Street, Chaoyang District, Beijing 100028, ChinaCNOOC Research Institute Ltd., CNOOC Building, Yard 6, Taiyanggong South Street, Chaoyang District, Beijing 100028, ChinaCollege of Geosciences and Surveying Engineering, China University of Mining & Technology, No. 11, Xueyuan Road, Haidian District, Beijing 100083, ChinaCollege of Mining Engineering, Taiyuan University of Technology, No. 79 Yingze Xi Street, Wanbolin District, Taiyuan 030002, ChinaSchool of Earth Resources, China University of Geosciences Wuhan, 388 Lumo Road, Wuhan 430074, ChinaIn the process of coalbed methane development, drilling fluid and fracturing fluid cannot achieve absolute compatibility with formation. The incompatibility between the working fluid and reservoir will lead to the intrusion of working fluid into the reservoir and cause reservoir pollution. This is a very common phenomenon. There is a large amount of pulverized coal in the coal seam, and the intrusion of working liquid will be combined with the pulverized coal to form cement to block the seepage space in the reservoir. Since pressure relief and fracturing fluid backflow will be performed at the first time after fracturing, the intrusion range of the working fluid is small, generally reaching 10 m to 50 m. Compared with a conventional gas reservoir or shale gas reservoir, the working fluid loss during CBM development will seriously affect the subsequent production project and even make the gas well lose production capacity. On the other hand, in order to avoid this phenomenon, measures such as acidification or volumetric fracturing are sometimes used to improve the seepage environment near the well and near the fracture. The purpose of this study is to quantitatively evaluate the impacts of working fluid filtration and reservoir reconstruction on production. In this study, a single well productivity evaluation model and sensitivity analysis method considering drilling fluid filtration loss, fracturing fluid filtration loss, reservoir reconstruction and other processes is proposed. The formation mechanism of fluid loss during drilling and fracturing is described, and the productivity evaluation model considering fluid loss is combined with the Langmuir isothermal adsorption equation, steady-state diffusion law, Darcy’s seepage law and Duhamel convolution formation. Combined with the distribution of actual gas reservoir flow characteristics, the sensitivity of single well productivity to gas reservoir porosity, gas reservoir permeability, coal seam adsorption coefficient, working fluid filtration loss and reservoir reconstruction measures are analyzed. Through the analysis and fitting of the actual production data on site, the relationship curve can better fit the field production data, and the evaluation results are in line with the drilling and fracturing conditions at that time and the subsequent production conditions, with small errors. The obtained method is suitable for predicting the productivity of fractured vertical wells in different working conditions and provides a basis for the development and productivity prediction of CBM reservoirs in China and in international cooperation.https://www.mdpi.com/1996-1073/17/7/1686coal bed methanedrilling fluid filtrationfracturing fluid filtrationreservoir reconstructionproductivity evaluation |
| spellingShingle | Chen Li Lichun Sun Zhigang Zhao Jian Zhang Yong Li Yanjun Meng Lei Wang A Method for Evaluating Coalbed Methane Reservoir Productivity Considering Drilling Fluid Damage Energies coal bed methane drilling fluid filtration fracturing fluid filtration reservoir reconstruction productivity evaluation |
| title | A Method for Evaluating Coalbed Methane Reservoir Productivity Considering Drilling Fluid Damage |
| title_full | A Method for Evaluating Coalbed Methane Reservoir Productivity Considering Drilling Fluid Damage |
| title_fullStr | A Method for Evaluating Coalbed Methane Reservoir Productivity Considering Drilling Fluid Damage |
| title_full_unstemmed | A Method for Evaluating Coalbed Methane Reservoir Productivity Considering Drilling Fluid Damage |
| title_short | A Method for Evaluating Coalbed Methane Reservoir Productivity Considering Drilling Fluid Damage |
| title_sort | method for evaluating coalbed methane reservoir productivity considering drilling fluid damage |
| topic | coal bed methane drilling fluid filtration fracturing fluid filtration reservoir reconstruction productivity evaluation |
| url | https://www.mdpi.com/1996-1073/17/7/1686 |
| work_keys_str_mv | AT chenli amethodforevaluatingcoalbedmethanereservoirproductivityconsideringdrillingfluiddamage AT lichunsun amethodforevaluatingcoalbedmethanereservoirproductivityconsideringdrillingfluiddamage AT zhigangzhao amethodforevaluatingcoalbedmethanereservoirproductivityconsideringdrillingfluiddamage AT jianzhang amethodforevaluatingcoalbedmethanereservoirproductivityconsideringdrillingfluiddamage AT yongli amethodforevaluatingcoalbedmethanereservoirproductivityconsideringdrillingfluiddamage AT yanjunmeng amethodforevaluatingcoalbedmethanereservoirproductivityconsideringdrillingfluiddamage AT leiwang amethodforevaluatingcoalbedmethanereservoirproductivityconsideringdrillingfluiddamage AT chenli methodforevaluatingcoalbedmethanereservoirproductivityconsideringdrillingfluiddamage AT lichunsun methodforevaluatingcoalbedmethanereservoirproductivityconsideringdrillingfluiddamage AT zhigangzhao methodforevaluatingcoalbedmethanereservoirproductivityconsideringdrillingfluiddamage AT jianzhang methodforevaluatingcoalbedmethanereservoirproductivityconsideringdrillingfluiddamage AT yongli methodforevaluatingcoalbedmethanereservoirproductivityconsideringdrillingfluiddamage AT yanjunmeng methodforevaluatingcoalbedmethanereservoirproductivityconsideringdrillingfluiddamage AT leiwang methodforevaluatingcoalbedmethanereservoirproductivityconsideringdrillingfluiddamage |