Lesson 26 * Well Control * * Variable Geometry * PETE 411 Well Drilling Lesson 26 * Well Control * * Variable Geometry *

Well Control-Variable Geometry Initial Shut-In Conditions Driller’s Method Kick at Casing Seat Kick at Surface Wait and Weight Method

Read: Applied Drilling Engineering, Ch. 4 HW #14: Driller’s Method - due 11-11-02 HW #15: W&W Method - due 11-15-02 Quiz B Thursday, Nov. 14, 7 - 9 p.m. Rm. 101 Closed Book 1 Equation sheet allowed, 8 1/2”x 11” (both sides)

Example Problem 1. Determine the pressure at the casing seat at 4,000’ when using the old mud (Driller’s) versus using the kill mud (Wait and Weight) to circulate a gas kick out of the hole. 2. Determine the casing pressure at the surface when the top of the gas bubble has just reached the surface, for the same two mud weights used above.

Example Problem Mud Weight = 10 ppg Well depth = 10,000’ Hole size = 10.5” Drill pipe = 4.5”, 16.60 #/ft Drill Collars = 8” * 3.5” * 500 ft Surface casing = 4,000’, 13-3/8”, 68 #/ft Mud Weight = 10 ppg Fracture gradient @ 4,000’ = 0.7 psi/ft

Example Problem Shut in Annulus Pressure, SICP = 400 psi Shut in Drillpipe Pressure, SIDPP = 200 psi Pit level increase = 20 barrels (kick size) Drop the Z terms but consider Temperature T at surface = 70 deg. F Temperature gradient = 1.2 deg.F/100 ft

Initial (Closed-In) Conditions: Initial mud gradient = 0.520 psi/ft (0.052 * 10 = 0.520)

Initial (Closed-In) Conditions: ( 20.28 ft/bbl )

4,000’ 9,500’ vdp.csg = 0.13006 bbl/ft vdp,hole = 0.08743 bbl/ft 10,000’ vdp,hole = 0.08743 bbl/ft vdc,hole = 0.04493 bbl/ft

Driller’s Method - kick at bottom F = DP * A = W

Driller’s Method - kick at csg. seat What is the pressure at 4,000 ft when the top of the kick fluid first reaches that point?

Top of Kick at Casing Seat Driller’s Method Top of Kick at Casing Seat 4,000’ 9,500’ 10,000’ P = 5,400 psi

Driller’s Method - kick at csg. seat Again, DP K_4,000 = 16.1 psi

Driller’s Method - kick at csg. seat

Driller’s Method - kick at csg. seat This results in the quadratic Eqn: With the solutions:

Driller’s Method - Top of Kick at Casing Seat P0,ann = ? P4,000 = 2,493 psi h4,000 = 441 ft DP = 16 psi BHP = 5,400 psi

Driller’s Method Top of Kick at Surface 4,000’ 9,500’ 10,000’ We need two equations… BHP = 5,400 psi

Driller’s Method - kick at surface When the bubble rises, it expands. The volume of the bubble at the surface is given by: (Z = const.)

Driller’s Method - kick at surface

Driller’s Method - kick at surface From Eq. (2), But, from Eq. (1),

Driller’s Method - kick at surface So, Quadratic equation . . .

Driller’s Method - kick at surface

Driller’s Method - kick at surface ( = 0.57 psi/ft )

Driller’s Method. Top of Kick at Surface P0,ann = 695 psi h0 = 974 ft DPK,0 = 11 psi P 4,000 = 2,280 psi P10,000 = ?

Wait and Weight Method - kick at casing seat Calculate the pressure at 4,000 ft when the top of the bubble reaches this point. Volume of bubble at 4,000 ft

Top of Kick at Casing Seat Wait and Weight Method Top of Kick at Casing Seat Old Mud Kill Mud

W&W - Pressure at top of kick at 4,000 ft Also,

Wait and Weight Method - kick at surface Capacity inside drill string = DP_cap. + DC_cap.

W&W - Pressure at top of kick - kick at 4,000 ft

W&W - Pressure at top of kick - kick at 4,000 ft

W&W - Pressure at top of kick - kick at 4,000 ft

Wait and Weight Method Top of Kick at Surface 4,000’ 9,500’ 10,000’ Old Mud Kill Mud

Wait and Weight Method - kick at surface Volume of gas bubble at surface:

Wait and Weight Method (Engineer’s Method) - kick at surface As before, Assume all 10 lb/gal mud is inside the 13 3/8” csg. Then the height of 10 lb mud:

Wait and Weight Method (Engineer’s Method) - kick at surface Hydrostatic head across the mud columns: Old Mud: Kill Mud:

Hydrostatics in Annulus W&W Method - kick at surface

Wait and Weight Method kick at surface From Eq. 4, substituting for h0

Wait and Weight Method - kick at surface Height of Bubble at Surface

Check Pressure at 4,000 ft - kick at surface Looks OK

Wait and Weight Method Top of Kick at Surface Old Mud P0,ann = 611 psi Kill Mud h0 = 1,109 ft DPK,0 = 11 psi DPOld Mud = 569 psi P 4,000 = 2,161 psi P10,000 = ?

Driller’s Engineer’s Method Method Summary Bubble at 10,000 ft Driller’s Engineer’s Method Method

Summary Top of Bubble at 4,000 ft Driller’s Engineer’s Method Method

Top of Bubble at surface Summary Top of Bubble at surface Driller’s Engineer’s Method Method

Why the difference?

Maximum Casing Pressure, psi Wait and Weight Method Kick Intensity, ppg

Kick Intensity, ppg Casing Pressure, psi Pump Strokes

Casing Pressure, psi Volume of Mud Pumped, bbl