Clean fracturing fluid

Abstract

The invention provides a clean fracturing fluid, which comprises the following ingredients (by weight): 2-4% of a densifier, 0-8% of potassium chloride, 0-10% of a modifier, 2-5% of a temperature-resistant reinforcing agent and the rest of fluid preparation water. The fracturing fluid can adopt acidic or alkaline fresh water or highly saline acid fracturing backflow fluid. After mechanical impurity removal treatment, highly saline backflow fluid can be used in fracturing fluid preparation of the next well without adjusting fluid preparation water quality in advance. Then, water quality chemical treatment process is omitted, and operating cost is greatly reduced. During site operation, efficient sand-carrying of the fracturing fluid is realized through a continuous mixing mode. Therefore, acid fracturing modification of a reservoir stratum and no falling of spent liquor during the whole oil and gas testing process are achieved, and ''zero pollution'' of borehole operation site is realized. The invention is helpful for cleaning and efficient production.

Description

technical field [0001] The invention relates to the research field of exploitation of oil and gas resources, in particular to a clean fracturing fluid. Background technique [0002] At present, hydraulic fracturing and acidizing are the main methods for the exploitation of unconventional oil and gas resources. However, after acidizing and fracturing operations, more than 30% of the gel-breaking fluid will be returned to the ground. Since this part of the flowback fluid contains formation crude oil Or condensate oil, high molecular polymers that are difficult to degrade, bacteria, contain calcium, magnesium, iron, zirconium, boron and other ions at the same time, and the pH range of the flowback liquid ranges from acidic span to alkaline, and it needs to be treated in depth After reaching the standard discharge or recycling, this leads to complex water treatment process, long construction period and sharp increase in operating costs; if it is directly discharged or evaporated...

AI Technical Summary

Problems solved by technology

[0002] At present, hydraulic fracturing and acidizing are the main methods for the exploitation of unconventional oil and gas resources. However, after acidizing and fracturing operations, more than 30% of the gel-breaking fluid will be returned to the ground. Since this part of the flowback fluid contains formation crude oil Or condensate oil, high molecular polymers that are difficult to degrade, bacteria, contain calcium, magnesium, iron, zirconium, boron and other ions at the same time, and the pH range of the flowback liquid ranges from acidic span to alkaline, and it needs to be treated in depth After reaching the standard discharge or recycling, this leads to complex water treatment process, long construction period and sharp increase in operating cost; if it is directly discharged or evaporated without treatment, it does not meet the current environmental protection requirements

[0003] At present, part of the reservoirs in Changqing oil and gas field are alkali-sensitive reservoirs, and it is difficult to realize the efficient development of reservoirs with conventional guar system. Although the application of hydroxypropyl guar system in conventional reservoirs can better meet the needs of oil field fracturing technology, but There are also problems such as complex recovery and reuse process after fracturing, too fast or weak cross-linking of recovered fluid remixing, some areas need to use chemical treatment equipment, and guar gum fracturing fluid and some clean fracturing fluids have counter ions Sensitivity to components or poor salt tolerance, especially for acidified and fractured construction wells, the flowback fluid is characterized by high salt content and acidic pH, which increases the risk of flowback fluid, especially acidification The difficulty and operating cost of recovery and reuse of fracturing flowback fluid also bring enormous pressure to environmental protection production and on-site construction