Well Control Methods: Driller's Method - formulas used in application WCMethods for iPhone

Well Control Methods applied on the drilling of the oil wells

Description

This application uses the basic calculations of the methods to control oil wells after the occurrence of kick during drilling operations on floating platforms and land rigs.

This full version is completely interactive and allows users to define a wide variety of parameters for oil wells and unit system, save data and more.

It is can be applied in the field of petroleum and also help in understanding the methods of well control.

Well Control Methods:

1. Driller's Method
2. Wait and Weight
3. Dynamic Volumetric
4. Static Volumetric - Migration / Bleed
5. Static Volumetric - Lubrication / Bleed

The Driller's Method

During drilling operation of oil wells, there may be inflow of formation fluids into the well, which is an undesirable condition. The driller should detect such events and closing the well immediately. Record information after the closing of the well corresponding to stabilization of pressure, volume gain, SIDPP (Shut-in Pressure Drillpipe) and SICP (Shut-in Casing Pressure. In the case of operations on floating units, this term could be redefined as Shut-in Choke Pressure).

The control method to be applied is the driller's method. That is to circulate the influx even with the original weight of the mud, keeping constant the circulation pressure named ICP - Initial Pressure Circulation. The second circulation should be made with the kill mud weight in two steps: 1. Fill the drill string until the bit by keeping the pressure on the kill line constant and equal to SIDPP. 2. Complete circulation of the annulus to the surface keeping the pressure of circulation with the kill mud constant named FCP - Final Pressure Circulation.

Attention: about drill bit off bottom

This method should only be applied with the drill bit in the bottom hole or when the kick is completely in annullus of the column. To minimize errors of calculation of the kill mud weight, the calculations made in this application considers the depth of the drill bit instead of the depth of the well to calculate the kill mud weight. The formation pressure consider the depth of well. In case of top of the kick bellow the bit, it is recommended to apply the volumetric method until kick go through the drill bit to the annular, following then the driller's method.

Formulas:

ICP = Pks + SIDPP

ICP -  Inital Circulation Pressure, psi
  Pks - Recorded pump pressure at the kill rate speed, psi
  SIDPP - Shut-in Drillpipe Pressure, psi

  Notes about floating units:
     a) Pks must be recorded by circulating riser;
     b) Record the friction loss in the choke line at the kill rate speed, psi;

KM = OM + SIDPP / (0.052 x TVD)

KM - Kill Mud Weight, ppg
 OM - Original Mud Weight, ppg
 TVD - True Vertical Depth, ft

FCP = Pks x KM / OM

FCP - Final Circulation Pressure, psi

Summary of method

STEPS	PUMP PRESSURE	KILL PRESSURE	CHOKE PRESSURE	VOLUME TO PUMP
Bring the pump to kill speed	-	SICP	SICP - Choke line friction loss	-
Circulate out the influx to surface	ICP	-	-	Annulus Volume
Circulate to fill drill string with kill mud	-	SIDPP	SIDPP - Choke line friction loss	Drill string volume
Circulate to fill annulus with kill mud	FCP	-	-	Annulus Volume