kill procedures

Pressure ControlPressure Control

Kill ProceduresKill Procedures

Well Kill ProceduresWell Kill ProceduresDriller’s MethodDriller’s Method

The The Driller’s MethodDriller’s Method of controlling a of controlling a kick requires two circulations.kick requires two circulations.

The intruding formation fluid (gas, oil or The intruding formation fluid (gas, oil or salt water) is circulated out of the hole salt water) is circulated out of the hole during the first circulation while during the first circulation while holding a constant pressure against the holding a constant pressure against the formation to prevent further intrusion. formation to prevent further intrusion.


Holding a constant pressure against Holding a constant pressure against the formation while circulating out the the formation while circulating out the intruding formation fluid is achieved by intruding formation fluid is achieved by maintaining a constant drill pipe maintaining a constant drill pipe pressure while circulating at a pressure while circulating at a constant, predetermined rate through constant, predetermined rate through an adjustable choke. an adjustable choke.


This constant drill pipe pressure is This constant drill pipe pressure is controlled by pumping at a constant rate controlled by pumping at a constant rate while varying the size of the opening in the while varying the size of the opening in the choke.choke.

The drill pipe pressure is the sum of the The drill pipe pressure is the sum of the shut-in drill pipe pressure (SIDPP) and the shut-in drill pipe pressure (SIDPP) and the circulating pressure previously measured circulating pressure previously measured at a slow circulating rate.at a slow circulating rate.


The well is shut in again after The well is shut in again after circulating the intruding fluid out of the circulating the intruding fluid out of the hole.hole.

While the well is shut in, the weight of While the well is shut in, the weight of the surface mud is increased to the kill the surface mud is increased to the kill weight.weight.


After the weight of the surface mud has After the weight of the surface mud has been increased to the kill weight, the been increased to the kill weight, the kill weight mud is circulated throughout kill weight mud is circulated throughout the well while holding a constant the well while holding a constant pressure on the formation.pressure on the formation.

This constant pressure on the This constant pressure on the formation is controlled as follows:formation is controlled as follows:


This constant pressure on the formation is This constant pressure on the formation is maintained while pumping the kill weight mud maintained while pumping the kill weight mud down the drill string by maintaining the same down the drill string by maintaining the same constant circulating rate while using the adjustable constant circulating rate while using the adjustable choke to maintain a choke to maintain a constant casing pressureconstant casing pressure. .

This pressure should be the sum of the shut-in This pressure should be the sum of the shut-in casing pressure (SICP)+ 100 psi casing pressure (SICP)+ 100 psi (the 100psi is a safety margin and is optional)(the 100psi is a safety margin and is optional)

Well Kill ProceduresWell Kill ProceduresDriller’s MethodDriller’s Method After the kill mud reaches the bit, the After the kill mud reaches the bit, the

constant pressure on the formation is constant pressure on the formation is maintained by maintaining a constant maintained by maintaining a constant drill drill pipe pressurepipe pressure. .

This constant drill pipe pressure is This constant drill pipe pressure is maintained by adjusting the choke while maintained by adjusting the choke while maintaining a constant flow rate while.maintaining a constant flow rate while.


The constant drill pipe pressure at this The constant drill pipe pressure at this point is the point is the new circulating pressurenew circulating pressure..

The new slow circulating rate pressure The new slow circulating rate pressure is the slow circulating rate pressure is the slow circulating rate pressure increased due to the higher pressure increased due to the higher pressure losses resulting from the higher losses resulting from the higher density of the kill weight mud. density of the kill weight mud.


The new slow circulating rate pressure The new slow circulating rate pressure is calculated as follows:is calculated as follows:

O

KON WtMud

WtMudPP


New Slow Circulating Rate Pressure New Slow Circulating Rate Pressure (continued)(continued)

Where:Where: PPNN = = New Slow Circulating Rate Press.New Slow Circulating Rate Press. PPOO = Original Slow Circ. Rate Press. = Original Slow Circ. Rate Press. Mud WtMud WtK K = Kill Mud Weight= Kill Mud Weight Mud WtMud WtOO = Original Mud Weight = Original Mud Weight


After the mud in the hole is displaced After the mud in the hole is displaced by the kill weight mud, the hydrostatic by the kill weight mud, the hydrostatic pressure (Ppressure (PHYDHYD)) should balance the should balance the formation pressure (Pformation pressure (PFORMFORM) and the well ) and the well should be dead.should be dead.


Advantages of the Driller’s Method are:Advantages of the Driller’s Method are: The procedure is very simple to use.The procedure is very simple to use. After the intruding fluid has been After the intruding fluid has been

displaced on the first circulation, the displaced on the first circulation, the well can be shut in for an indefinite well can be shut in for an indefinite period of time if necessaryperiod of time if necessary


The only disadvantage of using the The only disadvantage of using the Drillers Method is that the pressure at Drillers Method is that the pressure at the casing seat is usually higher than the casing seat is usually higher than when using other procedures.when using other procedures.

Well Kill ProceduresWell Kill ProceduresWait & Weight MethodWait & Weight Method

The The Wait & WeightWait & Weight method of method of controlling a kick requires only one controlling a kick requires only one circulation.circulation.

In this procedure, the well remains shut In this procedure, the well remains shut in until the weight of the mud in the in until the weight of the mud in the surface pits is increased to the kill surface pits is increased to the kill weight. weight.


After the surface mud is increased to After the surface mud is increased to the kill mud weight, the mud in the hole the kill mud weight, the mud in the hole and the intruding formation fluid is and the intruding formation fluid is displaced by the kill weight mud in only displaced by the kill weight mud in only one circulation while maintaining a one circulation while maintaining a constant pressure on the formation. constant pressure on the formation.


The constant pressure on the formation The constant pressure on the formation is maintained by circulating at a is maintained by circulating at a constant slow circulating rate while constant slow circulating rate while maintaining the proper drill pipe maintaining the proper drill pipe pressure by adjusting the choke.pressure by adjusting the choke.


The initial circulating pressure is the sum of the The initial circulating pressure is the sum of the slow circulating rate pressure and the shut-in slow circulating rate pressure and the shut-in drill pipe pressure (SIDPP). drill pipe pressure (SIDPP).

As the kill weight mud is pumped down the drill As the kill weight mud is pumped down the drill pipe, the hydrostatic pressure (Ppipe, the hydrostatic pressure (PHYDHYD) in the drill ) in the drill string increases. To maintain a constant pressure string increases. To maintain a constant pressure on the formation, the drill pipe pressure must be on the formation, the drill pipe pressure must be reduced by adjusting the choke.reduced by adjusting the choke.


The proper drill pipe pressure versus time The proper drill pipe pressure versus time and/or pump strokes must be determined and/or pump strokes must be determined by calculations and strictly adhered to.by calculations and strictly adhered to.

Failure to do so would result in letting Failure to do so would result in letting more fluid into the well (not enough more fluid into the well (not enough pressure) or fracturing the formation pressure) or fracturing the formation (too (too much pressure).much pressure).


Specific instructions for kill procedures Specific instructions for kill procedures and necessary calculations are and necessary calculations are provided on the pressure control work provided on the pressure control work sheets.sheets.

Other pressure control definitions and Other pressure control definitions and calculations are covered in calculations are covered in “PRESSIndicators.ppt”“PRESSIndicators.ppt”


AdvantagesAdvantages of using the Wait & Weight of using the Wait & Weight method are:method are: Only one circulation is required to kill Only one circulation is required to kill

the well.the well. The pressure at the casing seat is The pressure at the casing seat is

usually lower when using this usually lower when using this method. method.


DisadvantagesDisadvantages when using the Wait & when using the Wait & Weight method are:Weight method are: The method is more complicated to The method is more complicated to

use than the Driller’s Methoduse than the Driller’s Method An extended time to increase the An extended time to increase the

density of the mud in the surface pits density of the mud in the surface pits will result in migration of the will result in migration of the intruding formation fluid up the hole. intruding formation fluid up the hole.

Well Kill ProceduresWell Kill ProceduresMixing RequirementsMixing Requirements

As the kill weight mud is pumped into As the kill weight mud is pumped into the hole, the lighter mud returns into the hole, the lighter mud returns into the surface pits. the surface pits.

Therefore, the mud density in the pits Therefore, the mud density in the pits will be reduced unless maintained with will be reduced unless maintained with additions of weight material.additions of weight material.

kill procedures

Documents

constant casing pressure

new circulating pressure

constant rate

kill weight mud

constant circulating

formation pressure pform

higher pressure losses

hydrostatic pressure