High oil-water ratiooil base drilling fluid system

Abstract

The invention discloses a high oil-water ratiooil base drilling fluid system. The system is prepared from, by volume, 90-95 parts of base oil and 5-10 parts of an aqueous phase, and further comprisesa primary emulsifier, an auxiliary emulsifier, a wetting agent, organic soil, calcium oxide, an emulsifying sealing material, a keritesealing material and calcium chloride brine, wherein the weight ofthe primary emulsifieris equal to 0.8-1.8% of the overall weight of the base oil and the aqueous phase, the auxiliary emulsifier1.0-2.0%, the wetting agent 1.2-1.5%, the organic soil 2.0-3.0%, the calcium oxide 3.0-4.0%, the emulsifying sealing material 3.5-4.5%, the keritesealing material 1-1.5% and the calcium chloride brine 2.0-2.5%. The high oil-water ratiooil base drilling fluid system is low in ECD value, has good emulsion stability, low rheological property and good well wall flushing capability, facilitates borehole cleaning, cost saving of drilling fluid and maintenance of on-site performanceof the drilling fluid, effectively reduces the risk of well leakage, and can avoid rheological propertyrise caused by drilling a stratum in which the moisture content is high.

Description

technical field [0001] The invention belongs to the field of drilling engineering for resources such as oil and natural gas, and in particular relates to an oil-based drilling fluid system with a high oil-water ratio. Background technique [0002] At present, with the increasing difficulty of drilling in the Beibu Gulf in the west of the South China Sea, oil-based drilling fluids have developed rapidly and become an important means of drilling difficult wells and reservoir protection. However, the existing oil-based drilling fluid still has many problems such as difficulty in tripping out, instability of the wellbore wall and poor cementing quality during use, which brings great losses to the drilling and completion operations. In addition, the existing oil-based drilling fluid has poor anti-pollution ability, and the formation fluid has a high degree of pollution to the drilling fluid system, which affects the stability of the drilling fluid to a certain extent, requires fr...

AI Technical Summary

Problems solved by technology

However, the existing oil-based drilling fluid still has many problems such as difficulty in tripping out, instability of the wellbore wall and poor cementing quality during use, which brings great losses to the drilling and completion operations.

In addition, the existing oil-based drilling fluid has poor anti-pollution ability, and the formation fluid has a high degree of pollution to the drilling fluid system, which affects the stability of the drilling fluid to a certain extent, requires frequent replacement of new slurry, and costs a lot

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