Well mouth flared short joint capable of improving measuring sensitivity of return flow rate of drilling liquid and method

Abstract

The invention relates to a well mouth flared short joint capable of improving measuring sensitivity of return flow rate of a drilling liquid and a method. The lower part of a lower casing is connected with a well mouth blowout preventer through a flange I, and the upper part of the lower casing is connected with the lower part of a trapezoidal structure body (4) through a flange II (3); the upper part of the trapezoidal structure body (4) is connected with an upper casing (7) through a flange III (6); the upper part of the upper casing (7) is movably connected with a mud umbrella (8), and the side surface of the upper casing (7) is movably connected with a mud return pipe (9). The well mouth flared short joint has the beneficial effects that (1) by utilizing a controllable semi-cylindrical rubber baffle plate, compared with other measuring types, the flowing cross section of returned drilling liquid is reduced, the return speed of the drilling speed is correspondingly increased, the influence by the radial speed of a drill stem is reduced, and the measuring accuracy is greatly improved; (2) by utilizing the trapezoidal structure body, compared with the square or cylindrical structure body, the distribution of flow lines and speed at the measuring point at one side of a trapezoid in the structure is ideal, and the measuring accuracy is greatly improved.

Description

technical field [0001] The invention relates to a drilling tool and a method, in particular to a wellhead bell-mouth nipple and a method for improving the measurement sensitivity of drilling fluid return flow. 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 ...

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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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