Well pressure control system

Abstract

The present invention contemplates a choke control system that provides for local and off-site monitoring and control of the annulus flow pressure of a well. The choke control system includes a choke manifold connected to at least one choke and its associated actuator; a variety of instrumental drilling sensors, pump stroke counter switches, and choke position indicators; a local choke and hydraulic pressure control console; and a programmable controller in communication with the local choke and hydraulic pressure control console. The programmable controller handles the logical operations of the choke control system, including processing instrument measurements and operator input data to produce control signals for operating the choke, the choke actuator and the various valves associated with the choke manifold. The programmable controller is typically either an electronic digital computer and / or a programmable logic controller (PLC). The present invention further contemplates the two-way communication between the choke control system and the Internet via a satellite linkage.

Description

CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application claims priority to pending U.S. Patent Application Serial No. 60 / 515,875 (Attorney Docket Number PC-P007V, filed Oct. 30, 2003 by John McCaskill, et al. and entitled “Hydraulic Choke Control System for Underbalanced Drilling.”FIELD OF THE INVENTION [0002] The present invention relates to an apparatus for maintaining well pressure control in various situations such as underbalanced, overbalanced, or other managed pressure drilling of petroleum wells, or the control of petroleum wells that are out of control or likely to become out of control. More particularly, the present invention relates to the operation of hydraulic choke valves for the maintenance of a constant drilling fluid pressure on the downhole formation face despite fluctuations arising due to mud pump speed changes or other causes. DESCRIPTION OF THE RELATED ART [0003] Hydraulic choke devices are commonly used in the oilfield when drilling wells for oil or n...

AI Technical Summary

Benefits of technology

[0010] The present invention contemplates a choke control system that provides for local and off-site monitoring and control of the annulus flow pressure. The choke control system includes a choke manifold connected to at least one choke and its associated actuator; a variety of instrumental drilling sensors, pump stroke counter switches, and choke position indicators; a local choke and hydraulic pressure control console; and a programmable controller in communication with the local choke and hydraulic pressure control console. The pro...

Problems solved by technology

Optimal drilling conditions for certain formations, particularly sources of desirable fluid production, require underbalanced conditions.

“Underbalanced” drilling encourages flow from the well, so that a hydraulic choke is typically used on the outlet from the well.

Undesirable variations in drilling fluid pressure may occur when changing the pumping rate of drilling fluid into the well unless the choke is appropriately adjusted to compensate.

However, it is difficult for a human operator to compensate for variations in dynamic flow pressure losses in the annulus around the drillstring as the pump rate into the well changes.

This approach takes time to balance the pressure.

Furthermore, this approach complicates the rig flow circuitry, as well as the well cost and maintenance, while not necessarily proving easy to control within the desired accuracy.

Another problem is that most underbalanced control systems respond to pressure reductions in the outflow pressure of a well.

Unfortunately when the pump rate into the well changes quickly and significantly, there is a time lag before the resultant reduced pressure is measured in the outflow pressure.

Damage to the well can occur if the downhole pressure is allowed to vary too much before it is corrected.

Thus, correcting reductions in the outflow pressure may not provide optimal timely control of the downhole pressure.

However, even this approach addresses the situation after the downhole pressure has changed.

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