Annular pressure adjusting system and method for well drilling

By setting up an annular pressure regulation system with short-section nozzles in the drilling system, the problem of well wall instability caused by the difference in the annular pressure of the upper and lower annular pressure in the deep well is solved, and the effect of optimizing the wellbore pressure distribution and reducing equipment load is achieved.

CN119664264APending Publication Date: 2025-03-21CHINA NAT PETROLEUM CORP +1
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Patent Information

Application Number
CN202311223968.6
Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Filing Date
2023-09-21
Publication Date
2025-03-21

AI Technical Summary

Technical Problem

During drilling of deep or ultra-deep wells, the pressure difference between the large gap annulus in the upper well section and the small gap annulus in the lower well section is large, resulting in the increase in the circulation friction resistance of the lower well section when the drilling fluid discharge increases, which may cause the well wall to be instable, and there is a difficulty in wellbore pressure control and the risk of leakage spray conversion in the multi-pressure system formation.

Method used

A drilling annular pressure regulation system is designed. By setting a short-section nozzle between the upper drilling rod, the lower drilling rod and the diversion short section, the drilling fluid flow of the upper large gap annular and the lower small gap annular respectively is adjusted, thereby adjusting the annular pressure. The system includes an upper drill pipe, a lower drill pipe and a short section of the shunt section. The main flow channel and a split channel are set up in the shunt section, and the segmented flow rate is controlled through the short section nozzle to regulate the annular pressure.

Benefits of technology

It achieves the requirements of rock carrying the upper large gap annulus and low cycle friction resistance requirements of the lower small gap annulus, optimizes the wellbore pressure distribution, reduces the load of drilling equipment, ensures safe and fast drilling, and reduces the risk of wellbore leakage.

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Abstract

The invention provides an annulus pressure adjusting system and method for well drilling, the adjusting system comprises an upper drill rod, a lower drill rod and a flow dividing short section, the upper drill rod, the lower drill rod and the flow dividing short section are all located in a casing pipe, and an annulus space is formed between the upper drill rod, the lower drill rod and the flow dividing short section and the casing pipe for circulation of drilling fluid; the annular space comprises an upper annular space and a lower annular space; the flow dividing short section, the upper drill rod and the lower drill rod are coaxially arranged, a main flow channel and a branch flow channel are arranged in the flow dividing short section, the main flow channel is communicated with the upper drill rod water hole and the lower drill rod water hole, the branch flow channel is communicated with the main flow channel and the annular space, and a short section nozzle is arranged in the branch flow channel. The method is realized by using the annulus pressure regulating system for well drilling, and comprises the following steps: determining a calculation model of the minimum safe rock-carrying flow; on the basis of the calculation model, other parameters are determined, and the opening degree of a short section nozzle is drawn up; and the opening degree of the short section nozzle is adjusted according to the set opening degree, and shunting is completed. According to the system, the leakage risk can be reduced. The method provided by the invention can prevent the borehole wall from instability.
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