Subsectional control device for drilling fluid density

Abstract

The invention relates to a subsectional control device for drilling fluid density. The subsectional control device comprises a joint body and a plurality of hollow balls with density lower than the drilling fluid density. The joint body is provided with a central hole running through axially; the central hole consists of an equal-diameter straight hole and a taper hole which are communicated witheach other, and the side wall of the joint body is provided with drain holes. A guide impeller cylinder is arranged in the equal-diameter straight hole, a plurality of vanes are arranged in the guideimpeller cylinder, a backflow via hole is formed in the guide impeller cylinder, a drain tube is fixedly arranged at the top of the guide impeller cylinder, the top of the drain pipe is communicated with the drain holes through transitional pipes, an overflow pipe extending downwards is fixedly arranged at the bottom of the guide impeller cylinder, and an inner cavity of the overflow pipe is communicated with the bottom of the backflow via hole hermetically. With application of the subsectional control device, variable-gradient drilling in deep water can be realized, and problems of excessivelayering in the process of running casings during single-gradient drilling, needing large-size equipment during double-gradient drilling and the narrow window of density in deep water drilling are allsolved while drilling cost is reduced.

Description

technical field [0001] The invention relates to the technical field of petroleum drilling, in particular to a drilling fluid density segmental control device. Background technique [0002] In recent years, 50% of the world's major oil and gas exploration and development has come from the ocean, mainly in deep water areas. Deep water areas have become an important replacement area for oil and gas exploration and development in the world. Deepwater oil and gas exploration and development are becoming the main growth point of world oil and the frontier of technological innovation, and deepwater will become the main battlefield for oil and gas resources in the future. [0003] Drilling is a key link in deepwater oil and gas exploration and development, and deepwater drilling faces many challenges and risks: (1) Challenges brought about by water depth. With the increase of water depth, higher requirements are put forward for drilling tools, drilling fluid, riser, platform bearin...

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Problems solved by technology

[0006] The object of the present invention is to provide a drilling fluid density segmental control device, through which deep water variable gradient drilling can be realized, which solves the problem of too many casing layers in single-gradient drilling, and also solves the problem of double-gradient drilling. The problem of requiring large equipment in drilling, reducing drilling costs, and finally solving the problem of narrow density windows in deepwater drilling

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