초록 ▼

A system for separation of fluids and drill cuttings received from a borehole during an under-balanced drilling procedure. The system is designed to cope with significantly varied pressures and flow rates, particularly in relation to gas content of drill fluids returned to the surface during the dri

A system for separation of fluids and drill cuttings received from a borehole during an under-balanced drilling procedure. The system is designed to cope with significantly varied pressures and flow rates, particularly in relation to gas content of drill fluids returned to the surface during the drilling process in a production zone, and to provide effective separation and to reduce the detrimental effect due to the presence of the drill cuttings in the returned drill fluids. In the present invention there is utilized a first stage, high pressure vessel in which a major portion of the gases ad drill cuttings are separated, and a second stage, horizontal low pressure vessel, preferably of greater volume than the high pressure vessel, in which further separating is achieved, including the separate removal of the drilling liquid to be returned to the drill tube. Because in under-balance drilling, the most serious variation in the pressure of the returning fluid is due to rapid increases in the proportion of gases in the drill fluid, the system of the present invention includes features allowing the control of the operating pressure in the high pressure vessel by way of the flow control of the gases exiting the high pressure vessel while the remaining separating procedure continues to provide effective results.

대표청구항 ▼

[ What I claim is:] [1.] A process for separating drilling fluids received from a borehole subject to formation pressure fluctuations during a downhole drilling operation utilizing an underbalanced drilling system, said process comprising:transferring said drilling fluids to a first stage, high pres

[ What I claim is:] [1.] A process for separating drilling fluids received from a borehole subject to formation pressure fluctuations during a downhole drilling operation utilizing an underbalanced drilling system, said process comprising:transferring said drilling fluids to a first stage, high pressure vessel,passing said drilling fluids through a first separator means in said high pressure vessel to separate a major portion of gases from liquids in said drilling fluids so that a first separated stream is produced,transferring said first separated stream from said high pressure vessel to a second stage, horizontal low pressure vessel,passing said first separated stream through a second separator means in said low pressure vessel for separating at least some of the residual gases from said first separated stream so that a second separated stream is produced,flowing said second separated stream through at least two separating chambers in said low pressure vessel while maintaining said second separated stream in said low pressure vessel at a liquid level within a predetermined range wherein said second separated stream is separated into at least two layers, a first layer comprising primarily a first liquid having a first density and a second layer comprising primarily a second liquid having a second density and further residual gases from said second separated stream escape to a gas collection zone above said liquid level, andcollecting at least a portion of liquid from at least one of said layers for return to said borehole, wherein an operating pressure in said high pressure vessel is maintained within a predetermined range by controlling the outflow of gas from said high pressure vessel, in response to pressure fluctuations in said borehole outside the predetermined range.