Drilling fluid for resisting heavy oil pollution

Abstract

The invention relates to the technical field of drilling fluids used in petroleum drilling engineering, and particularly discloses a drilling fluid for resisting heavy oil pollution. The drilling fluid is prepared by mixing water, sodium bentonite, sodium carbonate, sodium carboxymethyl cellulose, low viscosity polyanionic cellulose, a filtrate loss reducer A, sulfonated phenolic resin, sulfonated lignite, industrial salt, an emulsifier B, an emulsifier C and barite, adjusting the pH value to 10 to 11 and aging at high temperature. The drilling fluid is prepared by reasonably compounding and synergistic effect of the above raw materials, can maintain good rheological properties, also increases significantly the capacity limitation of heavy oil, after the drilling fluid is polluted by 25% heavy oil, the drilling fluid still has good rheology and filtration loss property, the viscosity of the drilling fluid is effectively reduced, and the phenomenon of pasting a vibration sieve can be eliminated.

Description

technical field [0001] The invention relates to the technical field of drilling fluid for petroleum drilling engineering, in particular to a heavy oil pollution-resistant drilling fluid. Background technique [0002] As the recoverable reserves of conventional oil are decreasing, heavy oil (also known as heavy oil) has attracted more and more attention because of its resource potential several times higher than conventional oil resources, and is becoming an important substitute for global conventional oil resources. energy. According to relevant statistics, heavy oil accounts for more than 70% of the world's remaining oil resources, and there are 192 heavy oil-bearing basins, with original geological reserves of 4.9×10 11 t. Heavy oil and bitumen resources show the characteristics of concentrated distribution. At present, the proven heavy oil resources in the world are mainly concentrated in Venezuela, the former Soviet Union, the United States, Canada and other countries....

AI Technical Summary

Problems solved by technology

Heavy oil pollution problems are mainly manifested in: (1) The performance of drilling fluid deteriorates, the viscosity and shear force of the funnel increase suddenly, and even the fluidity is lost; (2) The screen cloth of the vibrating screen is blocked, causing the drilling fluid to run out of slurry and increasing the cost of drilling fluid; ( 3) Heavy oil forms a layer of oil film on the outer wall of the casing and the well wall, which affects the cementation of the cement slurry, the casing, and the formation, and affects the cementing construction, resulting in poor cementing quality

The existence of the above problems can easily lead to blockage of the annular space, induce complex situations such as blowout or leakage, and affect the safety of drilling construction

[0005] At present, crude oil is often used as a lubricant in on-site drilling operations. The content of crude oil in drilling fluid is generally 3% to 8%, which can form a stable emulsion. Rheology is difficult to control; conventional oil-in-water drilling fluids generally use light oil such as diesel oil or white oil as the oil phase in order to meet the purpose of safe drilling in low-pressure and leaky formations, with low density

"Drilling and Production Technology" No. 4, 2012, the article "Treatment Technology of Drilling Fluid Contaminated by Heavy Oil" introduces the methods of on-site treatment of drilling fluid invaded by heavy oil. Applicable when the speed is slow and the amount of intrusion is low; another method is the emulsification dispersion method, which uses up to 5% to 20% diesel oil to disperse the heavy oil and then emulsifies it. Due to the low density and large amount of diesel oil, this method will As a result, the density of the drilling fluid is further reduced, and the density of the drilling fluid needs to be adjusted frequently. There is a risk that the formation pressure cannot be balanced, causing wellbore instability, well kick or even blowout. cost of drilling

Therefore, the existing drilling fluids cannot well meet the requirements of dealing with heavy oil pollution during drilling operations in heavy oil reservoirs, and the drilling fluids are faced with the problem of maintaining good rheological properties while increasing the capacity limit of heavy oil

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