Positive cycle nonlinear displacement control method for strong drilling of sulfur-containing and gas-containing stratum

By using a positive circulation nonlinear displacement control method to measure and adjust the drilling fluid column height and maintain annular fluid column pressure balance, the well control risks and wellbore instability in sulfur- and gas-bearing formations are solved, achieving wellbore stability and improved drilling efficiency.

CN121993064APending Publication Date: 2026-05-08CHINA NAT PETROLEUM CORP +1
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
CHINA NAT PETROLEUM CORP
Filing Date
2024-11-06
Publication Date
2026-05-08

AI Technical Summary

Technical Problem

In sulfur- and gas-bearing formations, existing technologies struggle to effectively control well control risks and maintain a high balance of annular fluid levels, leading to wellbore instability, consuming significant human and material resources, and incurring high costs.

Method used

The positive circulation nonlinear displacement control method is adopted. By measuring and adjusting the static and dynamic fluid levels of the drilling fluid column, the fluid column pressure is calculated to balance the formation pressure. Using the clear water high-power drilling technology, cuttings are introduced and the annular fluid column pressure is kept slightly higher than the formation pressure to protect the wellbore stability.

Benefits of technology

It achieves stable wellbore pressure during high-intensity drilling in clear water, reduces drilling costs, improves drilling efficiency, prevents well leakage and wellbore collapse, and ensures wellbore cleanliness.

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Abstract

The invention discloses a positive cycle non-linear displacement control method for strong drilling of a sulfur-containing and gas-containing stratum, which belongs to the technical field of displacement control methods and comprises the following steps of: measuring the static liquid level height of a drilling fluid column before a drilling pump is started under the condition of leakage return of a drilled well; measuring the working fluid level height after well drilling pump starting is stable; calculating the liquid column pressure before pump starting according to the static liquid level height of the drilling liquid column; calculating formation pressure after pump starting is stabilized according to the working fluid level height; comparing whether the liquid column pressure before pump starting and the formation pressure after pump starting stabilization are balanced or not; if not, the annulus dynamic liquid level height is adjusted, the annulus liquid column pressure is kept equal to or larger than the formation pressure all the time, and the annulus liquid column pressure is made to stably press the leakage layer; and after the leakage layer is stably pressed, clear water with different discharge capacities is adopted to bring drilled rock debris into the leakage layer under different annular gaps of the drill collar section and the drill rod section. In the process of clear water forced drilling, the height of the annular liquid level above a leakage layer is controlled through positive circulation, so that the annular liquid column pressure is larger than the formation pressure, and an air layer is stably pressed to prevent overflow.
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