Wellhead bell-mouth nipple that improves the measurement sensitivity of drilling fluid return flow

Abstract

The invention relates to a wellhead bell mouth nipple which improves the measurement sensitivity of drilling fluid return flow. The lower part of the lower casing is connected to the wellhead blowout preventer through flange one, and the upper part is connected to the lower part of the trapezoidal structure (4) through flange two (3); the upper part of the trapezoidal structure (4) is connected to the upper casing through flange three (6) The pipe (7) is connected; the upper part of the upper casing (7) is movably connected with the mud umbrella (8), and the side is movably connected with the mud return pipe (9); beneficial effects: (1) Compared with other measurement methods, the present invention , using the controllable semi-cylindrical rubber baffle to reduce the flow cross-sectional area of ​​the drilling fluid returning, correspondingly increasing the drilling fluid return speed, and at the same time reducing the impact of the radial velocity of the drill string, greatly improving the Measurement accuracy; (2), the present invention utilizes the trapezoidal structure relative to the square or cylindrical structure, and the streamline and velocity distribution at the measurement point on one side of the trapezoid in the structure are ideal, which greatly improves the measurement accuracy.

Description

technical field [0001] The invention relates to a drilling tool, in particular to a wellhead bell mouth nipple which improves the measurement sensitivity of the return flow rate of drilling fluid. Background technique [0002] In the process of oil and gas drilling, measuring the flow rate of drilling fluid is one of the important tasks in the process of oil exploration and development. When the gas invades the drilling fluid, how to measure the drilling fluid return with high precision, reality and accuracy has become a problem that the oil industry needs to explore. It is necessary to judge whether it is overflowing early, and then take effective measures to prevent blowout and blowout out of control, and reduce various losses. [0003] There are currently several solutions for the measurement of the return flow of drilling fluid. Among them, the baffle flowmeter is the most widely used. Using the principle of the baffle, when the drilling fluid flows through the baffle, i...

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Problems solved by technology

The disadvantage of this method is that it is sensitive to the volume of the container. The larger the volume of the container, the smaller the change in the liquid level when the volume changes are the same. For example, when the flow rate increases from 24L / s to 25L / s, in a 5m square mud pool Among them, the liquid level change in 1 hour is 16.61mm, and the delay is long, which is difficult to meet the needs of high-precision measurement of the drilling fluid flow rate of the return pipeline on site.

[0005] The third way to measure the flow rate of drilling fluid is to measure the branch flow through the branch pipe to reflect the flow rate of the return pipeline. The principle is to connect a section of branch pipe in parallel under the return pipeline, and measure the flow rate of the small pipe to reflect the flow rate of the return pipeline. The disadvantages are: The free liquid surface has little effect on the flow of the branch pipe. When the return flow is doubled, the flow of the branch pipe will change significantly. The accuracy is low and cannot meet the actual needs.

[0006] In addition, although some other flowmeters, such as orifice flowmeters and electromagnetic flowmeters, are widely used in other industries, the flow rate of the return pipeline is not full, which greatly affects the measurement accuracy.

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