Mud for large borehole drilling

Abstract

The present invention provides a mud for large borehole drilling in oil drilling, and belongs to the field of oil drilling engineering. In order to solve the problem that in a oil drilling process, large borehole can easily cause wall collapse, which seriously affects the drilling speed and efficiency, and hinder progress of oil exploration and development work, the present invention provides the mud for large borehole drilling. The formula is: 30-40 parts of bentonite; 0.2-0.3 part of positive gel; 0.2-0.3 part of positive gel structuring agent; 0.6-1 part of sulfonated lignin sulfonic methyl phenol resin; 3-5 parts of lignite resin; 3-5 parts of sulfonated asphalt; 0.03-0.05 part of copolymers of vinyl monomers polyhydric; 1-3 parts of sulfonated phenol-formaldehyde resin; and 1000 parts of water. According to the mud for large borehole drilling provided by the present invention, raw materials and content for choice has outstanding leak-proof and wall protection effects, and applies to drilling in understable highly deviated wells, horizontal wells, easily dilapidated strata, and large wellbore with high earth strata dips, and high and steep constructions in East Sichuan region.

Description

technical field [0001] The invention belongs to the field of oil field drilling engineering, and in particular relates to a mud used for drilling large boreholes in oil drilling. Background technique [0002] The so-called "big wellbore" refers to the wellbore with a diameter of more than 241mm, generally including 311mm, 346mm, 394mm, 440mm and so on. There are often many problems in the construction of large boreholes, and the construction speed is slow. The main technical problems are: 1. The purpose of large boreholes is to run large casings to seal the upper leaky formations, but the lithology of the formations is loose and the cementation is poor. Good drillability, high porosity, good permeability, fast drilling speed, coupled with large annular space, low return speed of mud annular space, difficulty in carrying rock, prone to lost circulation, even lost circulation and stuck sand; 2. Irregular borehole diameter in the upper strata is easy to form "big belly" and "s...

AI Technical Summary

Problems solved by technology

There are often many problems in the construction of large boreholes, and the construction speed is slow. The main technical problems are: 1. The purpose of large boreholes is to run large casings to seal the upper leaky formations, but the lithology of the formations is loose and the cementation is poor. Good drillability, high porosity, good permeability, fast drilling speed, coupled with large annular space, low return speed of mud annular space, difficulty in carrying rock, prone to lost circulation, even lost circulation and stuck sand; 2. Irregular borehole diameter in the upper strata is easy to form "big belly" and "sugar gourd" boreholes, which bury hidden dangers for safe drilling, causing various complicated situations such as stuck pipe, resistance in electrical testing and resistance in running casing at the well site and downhole accidents; 3. It is difficult to control the wellbore trajectory, and the build-up rate is low when the large wellbore is oriented, and the trajectory is not easy to control

It is necessary to choose a good build-up tool. If the build-up rate is high, it is easy to cause difficulty in running casing at the build-up point; 4. The lower formation has poor drillability, and the drilling pressure per unit area of ​​the drill bit is low, making it difficult for high-pressure jet drilling to perform well. effect, due to the lower power of the drill bit than the water

[0003] Therefore, during the drilling of large boreholes, the well wall often collapses, which seriously affects the speed and efficiency of drilling work, and hinders the progress of the exploration and development of the oilfield.