Pressure Control –Well Control Procedures

this will be into 2 topics
Well Control Procedures 1

•Kick Detection
–Early detection of a kick is important.
–It can reduce the size of the kick, lower the quantity of pressure exerted on the casing shoe and simplify regaining control of the well.
•Indications that a kick has entered the well are:
–Increases in flow at the flow line.
–Increases in pit volume.
–Flow with the pump off.
–Hole taking insufficient mud volume on trip.
•Shut in the well
–When the warning signs of a kick are recognized, steps should be taken immediately to determine if the well is flowing and to shut the well in as quickly and safely as possible, to prevent any further influx into the wellbore.
–Reducing the size of the influx is a high-priority objective.
–A kick can occur while drilling or while tripping.
•Well Control Methods
–Once the well has been shut in, steps should be taken to circulate the intruding fluid out of the well.
–Also, the density of the drilling fluid should be increased to provide sufficient hydrostatic pressure to control the formation pressure.
–Over the years, several methods have been developed to circulate the kick out and weight up the drilling fluid.
–All recognized well-control methods use a constant, but slow, pump rate when circulating a kick out of the hole and replacing the light mud with kill mud.
–Additional formation fluids must be kept from entering the wellbore while the kick is being circulated out of the well and the weighted kill mud is being circulated.
–If the kick has not been allowed to flow back through the drill pipe and the bit is on bottom, the shut-in drill pipe pressure plus the hydrostatic pressure (PHYD) of the mud in the drill pipe is equal to the formation pressure.
–The information that should be recorded after taking a kick are:
•Measured depth.
•Total vertical depth.
•Mud weight.
•Shut-In Drill Pipe Pressure (SIDPP).
•Shut-In Casing Pressure (SICP).
•Kick volume.
•Fractured gradient.
•Casing TVD.
•Reduced Circulating Pressure (RCP).
•Reduced Circulating Rate (RCR).
•Reduced Pump Output (RPO).
–If off-bottom:
•Measured depth of bit.
•TVD of bit
–The first 6 items are taken at the time the kick is taken and the well is shut in.
–The next five items should be known or measured prior to taking a kick.
–They must be used to make the necessary calculations to circulate the kick out of the hole and to kill the well.
–The last 2 items apply if the kick occurs while tripping.
•The Driller’s Method
–The simplest of the approved well-control methods.
–It was developed to circulate the kick out of the well and circulate the kill mud into the well (in two circulations) with a minimum number of calculations.
–The method’s original purpose was to control wells with minimal supervision, poor mixing capabilities or insufficient weighting material on location.
•The Driller’s Method Procedure
–Shut the well in and record the pertinent kick information.
–Calculate the Initial Circulation Pressure (ICP):
ICP = RCP + SIDPP
–Open the adjustable choke and start pumping at the pre-selected slow pump rate.
–Adjust the choke to obtain a pump pressure equal to the ICP.
–Circulate the kick out by maintaining the ICP using the adjustable choke.
–Maintain a constant pump rate throughout the circulating process.
–Once the kick has been circulated out of the well, the well can be shut in.
–The SIDPP and the SICP should be equal, since the intruding fluid has been circulated out of the well.
–Calculate the kill-mud weight and weight up the fluid in the surface system.
–Open the adjustable choke and start pumping at the pre-selected slow pump rate.
–Adjust the choke to maintain the casing pressure at the SICP.
–Maintain the mud weight in the surface system at the kill-mud weight.
–Once the kill mud reaches the bit, record the pump pressure.
–Maintain this pump pressure by adjusting the choke until the kill mud is observed at the surface.
–Stop pumping and shut the well in to check for pressures.
–If shut in pressure exists, additional mud weight and circulation will be required.
–If no shut-in pressures exists, the well is under control.
–At this time, one or two circulations may be made to condition the mud and increase the mud weight to provide a trip margin.
•Driller’s Method
–Advantages
•Involves a minimal number of calculations (3).
•A simple procedure that can be understood by most rig crews.
•Removes the intruding fluid from the well in a minimum amount of time.
–Disadvantages
•Requires two circulations to kill the well.
•Subjects the casing shoe to the maximum amount of pressure due to no additional hydrostatic pressure from additional mud weight.