Plugging mechanisms of polymer gel used for hydraulic fracture water shutoff
The performance of polymer gel to plug a hydraulic fracture is greatly affected by its distribution patterns and gelling effect. In this study, the migration of a gel plugging agent in a fracture and its plugging after gelling were investigated by physical simulation experiments. In addition, the di...
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2020-07-01
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doaj-308f3da7cc58466187b68544b35dbc352021-02-28T21:53:10ZengDe Gruytere-Polymers1618-72292020-07-0120141142210.1515/epoly-2020-0045epoly-2020-0045Plugging mechanisms of polymer gel used for hydraulic fracture water shutoffZhang Song0Wei Falin1Liu Pingde2Shao Liming3Li Weitao4Department of Oilfield Chemistry, Research Institute of Petroleum Exploration and Development, PetroChina, Beijing, 100083, ChinaDepartment of Oilfield Chemistry, Research Institute of Petroleum Exploration and Development, PetroChina, Beijing, 100083, ChinaDepartment of Oilfield Chemistry, Research Institute of Petroleum Exploration and Development, PetroChina, Beijing, 100083, ChinaDepartment of Oilfield Chemistry, Research Institute of Petroleum Exploration and Development, PetroChina, Beijing, 100083, ChinaDepartment of Oilfield Chemistry, Research Institute of Petroleum Exploration and Development, PetroChina, Beijing, 100083, ChinaThe performance of polymer gel to plug a hydraulic fracture is greatly affected by its distribution patterns and gelling effect. In this study, the migration of a gel plugging agent in a fracture and its plugging after gelling were investigated by physical simulation experiments. In addition, the distribution patterns of the gel plugging agent and its plugging mechanism after gelling were investigated in detail. The results of this study revealed that the migration flowing behavior of the gel solution in a fracture can be divided into three streams: fracture flow, leak off flow, and matrix flow. Such behavior distributed the gel in three different patterns after gelling: gel clusters in the fracture, gel layer on the fracture surface, and dispersed gel lumps in the matrix pores-throats. Because of the leak off flow and the difference in components, the gel solution has apparent disproportional leak off–diffusion of components during its migration in a fracture, with less polymer molecules and loss of more cross-linking agent ions. The leak off of the cross-linking agent significantly deteriorates the gelling strength of the polymer gel, affecting its performance to plug a hydraulic fracture. The results also show that when the normalized concentration of the cross-linking agent ions in a fracture is less than 0.6, gel fails to plug the fracture effectively after gelling. When gelling was carried out by in situ cross-linking, polymer gel provided more satisfactory plugging performance than the gelling via ground pre-cross-linking.http://www.degruyter.com/view/j/epoly.2020.20.issue-1/epoly-2020-0045/epoly-2020-0045.xml?format=INTfracture water shutoffpolymer geldistribution patternleak off degreeplugging mechanism |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Zhang Song Wei Falin Liu Pingde Shao Liming Li Weitao |
spellingShingle |
Zhang Song Wei Falin Liu Pingde Shao Liming Li Weitao Plugging mechanisms of polymer gel used for hydraulic fracture water shutoff e-Polymers fracture water shutoff polymer gel distribution pattern leak off degree plugging mechanism |
author_facet |
Zhang Song Wei Falin Liu Pingde Shao Liming Li Weitao |
author_sort |
Zhang Song |
title |
Plugging mechanisms of polymer gel used for hydraulic fracture water shutoff |
title_short |
Plugging mechanisms of polymer gel used for hydraulic fracture water shutoff |
title_full |
Plugging mechanisms of polymer gel used for hydraulic fracture water shutoff |
title_fullStr |
Plugging mechanisms of polymer gel used for hydraulic fracture water shutoff |
title_full_unstemmed |
Plugging mechanisms of polymer gel used for hydraulic fracture water shutoff |
title_sort |
plugging mechanisms of polymer gel used for hydraulic fracture water shutoff |
publisher |
De Gruyter |
series |
e-Polymers |
issn |
1618-7229 |
publishDate |
2020-07-01 |
description |
The performance of polymer gel to plug a hydraulic fracture is greatly affected by its distribution patterns and gelling effect. In this study, the migration of a gel plugging agent in a fracture and its plugging after gelling were investigated by physical simulation experiments. In addition, the distribution patterns of the gel plugging agent and its plugging mechanism after gelling were investigated in detail. The results of this study revealed that the migration flowing behavior of the gel solution in a fracture can be divided into three streams: fracture flow, leak off flow, and matrix flow. Such behavior distributed the gel in three different patterns after gelling: gel clusters in the fracture, gel layer on the fracture surface, and dispersed gel lumps in the matrix pores-throats. Because of the leak off flow and the difference in components, the gel solution has apparent disproportional leak off–diffusion of components during its migration in a fracture, with less polymer molecules and loss of more cross-linking agent ions. The leak off of the cross-linking agent significantly deteriorates the gelling strength of the polymer gel, affecting its performance to plug a hydraulic fracture. The results also show that when the normalized concentration of the cross-linking agent ions in a fracture is less than 0.6, gel fails to plug the fracture effectively after gelling. When gelling was carried out by in situ cross-linking, polymer gel provided more satisfactory plugging performance than the gelling via ground pre-cross-linking. |
topic |
fracture water shutoff polymer gel distribution pattern leak off degree plugging mechanism |
url |
http://www.degruyter.com/view/j/epoly.2020.20.issue-1/epoly-2020-0045/epoly-2020-0045.xml?format=INT |
work_keys_str_mv |
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