Anti-collapse mechanism of CBM fuzzy-ball drilling fluid
Although fuzzy-ball drilling fluid has been successfully applied in CBM well drilling, it is necessary to study its anti-collapse mechanism so that adjustable coalbed sealing effects, controllable sealing strength, rational sealing cost and controllable reservoir damage degree can be realized. In th...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
KeAi Communications Co., Ltd.
2016-03-01
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| Series: | Natural Gas Industry B |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S2352854016300298 |
| _version_ | 1797283778301788160 |
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| author | Lihui Zheng Biwu Chen Zheng Zhang Jidan Tang Hao Sun |
| author_facet | Lihui Zheng Biwu Chen Zheng Zhang Jidan Tang Hao Sun |
| author_sort | Lihui Zheng |
| collection | DOAJ |
| description | Although fuzzy-ball drilling fluid has been successfully applied in CBM well drilling, it is necessary to study its anti-collapse mechanism so that adjustable coalbed sealing effects, controllable sealing strength, rational sealing cost and controllable reservoir damage degree can be realized. In this paper, laboratory measurement was performed on the uniaxial compressive strength of the plungers of No. 3 coalbed in the Qinshui Basin and the inlet pressure of Ø38 mm coal plunger displacement. The strengths of coal plungers were tested and compared after 2% potassium chloride solution, low-solids polymer drilling fluid and fuzzy-ball drilling fluid were injected into the coal plungers respectively. It is shown that coal strength rises by 38.46% after the fuzzy-ball drilling fluid is injected (in three groups); and that no fuzzy-ball drilling fluid is lost at the displacement pressures of 20.73 and 21.46 MPa, nor 2% potassium chloride solution is leaked at such pressures of 24.79 and 25.64 MPa after the plunger was sealed by the fuzzy-ball drilling fluid. This indicates that the fuzzy-ball drilling fluid can increase the formation resistance to fluid. Indoor microscopic observation was conducted on the sealing process of the fuzzy-ball drilling fluid in sand packs with coal cuttings of three grain sizes (60–80, 80–100 and 100–120 mesh). It is shown that the leakage pathways of different sizes are sealed by the vesicles in the form of accumulation, stretch and blockage. And there are vesicles at the inlet ends of the flowing pathways in the shape of beaded blanket. The impact force of drilling tools on the sidewalls is absorbed by the vesicles due to their elasticity and tenacity, so the sidewall instability caused by drilling tools is relieved. It is concluded that the main anti-collapse mechanisms of the CBM fuzzy-ball drilling fluid are to raise the coal strength, increase the formation resistance to fluid, and buffer the impact of drill tools. |
| first_indexed | 2024-03-07T17:35:45Z |
| format | Article |
| id | doaj.art-270560ff74c44b32896ca14ec3c06149 |
| institution | Directory Open Access Journal |
| issn | 2352-8540 |
| language | English |
| last_indexed | 2024-03-07T17:35:45Z |
| publishDate | 2016-03-01 |
| publisher | KeAi Communications Co., Ltd. |
| record_format | Article |
| series | Natural Gas Industry B |
| spelling | doaj.art-270560ff74c44b32896ca14ec3c061492024-03-02T16:46:07ZengKeAi Communications Co., Ltd.Natural Gas Industry B2352-85402016-03-013215215710.1016/j.ngib.2016.03.011Anti-collapse mechanism of CBM fuzzy-ball drilling fluidLihui Zheng0Biwu Chen1Zheng Zhang2Jidan Tang3Hao Sun4China University of Petroleum, Beijing, 102249, ChinaCBM Branch Company, PetroChina Huabei Oilfield Company, Changzhi, Shanxi, 046000, ChinaChina University of Petroleum, Beijing, 102249, ChinaChina University of Petroleum, Beijing, 102249, ChinaChina University of Petroleum, Beijing, 102249, ChinaAlthough fuzzy-ball drilling fluid has been successfully applied in CBM well drilling, it is necessary to study its anti-collapse mechanism so that adjustable coalbed sealing effects, controllable sealing strength, rational sealing cost and controllable reservoir damage degree can be realized. In this paper, laboratory measurement was performed on the uniaxial compressive strength of the plungers of No. 3 coalbed in the Qinshui Basin and the inlet pressure of Ø38 mm coal plunger displacement. The strengths of coal plungers were tested and compared after 2% potassium chloride solution, low-solids polymer drilling fluid and fuzzy-ball drilling fluid were injected into the coal plungers respectively. It is shown that coal strength rises by 38.46% after the fuzzy-ball drilling fluid is injected (in three groups); and that no fuzzy-ball drilling fluid is lost at the displacement pressures of 20.73 and 21.46 MPa, nor 2% potassium chloride solution is leaked at such pressures of 24.79 and 25.64 MPa after the plunger was sealed by the fuzzy-ball drilling fluid. This indicates that the fuzzy-ball drilling fluid can increase the formation resistance to fluid. Indoor microscopic observation was conducted on the sealing process of the fuzzy-ball drilling fluid in sand packs with coal cuttings of three grain sizes (60–80, 80–100 and 100–120 mesh). It is shown that the leakage pathways of different sizes are sealed by the vesicles in the form of accumulation, stretch and blockage. And there are vesicles at the inlet ends of the flowing pathways in the shape of beaded blanket. The impact force of drilling tools on the sidewalls is absorbed by the vesicles due to their elasticity and tenacity, so the sidewall instability caused by drilling tools is relieved. It is concluded that the main anti-collapse mechanisms of the CBM fuzzy-ball drilling fluid are to raise the coal strength, increase the formation resistance to fluid, and buffer the impact of drill tools.http://www.sciencedirect.com/science/article/pii/S2352854016300298CBMDrillingWellbore stabilityFuzzy-ball drilling fluidAnti-collapse mechanismQinshui BasinLaboratory test |
| spellingShingle | Lihui Zheng Biwu Chen Zheng Zhang Jidan Tang Hao Sun Anti-collapse mechanism of CBM fuzzy-ball drilling fluid Natural Gas Industry B CBM Drilling Wellbore stability Fuzzy-ball drilling fluid Anti-collapse mechanism Qinshui Basin Laboratory test |
| title | Anti-collapse mechanism of CBM fuzzy-ball drilling fluid |
| title_full | Anti-collapse mechanism of CBM fuzzy-ball drilling fluid |
| title_fullStr | Anti-collapse mechanism of CBM fuzzy-ball drilling fluid |
| title_full_unstemmed | Anti-collapse mechanism of CBM fuzzy-ball drilling fluid |
| title_short | Anti-collapse mechanism of CBM fuzzy-ball drilling fluid |
| title_sort | anti collapse mechanism of cbm fuzzy ball drilling fluid |
| topic | CBM Drilling Wellbore stability Fuzzy-ball drilling fluid Anti-collapse mechanism Qinshui Basin Laboratory test |
| url | http://www.sciencedirect.com/science/article/pii/S2352854016300298 |
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