Drilling Tutorials 2011

Ex. 1 Leakoff Test

After having conducted a Leak off test at the 13 3/8" casing shoe of a vertical well the following data is reported :

TVD of 13 3/8" Shoe : 5200 ft. Mudweight in hole : 10.0 ppg

1. What is the maximum allowable static mudweight in the next (12 1/4") hole section?

1. Assuming that the circulating pressure losses in the annulus will be 200psi, what is the maximum allowable mudweight, (allowing for ECD) in the next (12 1/4") hole section?

11. What would be the MAASP in the next hole section, if the mudweight in the next hole section was increased to 11.0 ppg ?

(State clearly any assumptions in your answer) (6)

Drilling Tutorials 2011

Ex. 2 Well Control

Whilst drilling the 12 1/4" hole section of a vertical well with a mudweight of 10.5 ppg the driller detects a kick. The well is shut in and the following information is gathered

Surface Readings :

Shut in Drillpipe Pressure : 700 psi Shut in Annulus Pressure : 900 psi Pit Gain : 33 bbls

Hole / Drillstring Data :

Hole Size : 12 1/4 "

Depth of kick : 7250 ft. TVD Previous Casing Shoe : 13 3/8", 53.5 lb/ft Depth 13 3/8" shoe : 3800 ft. TVD

LOT at Previous shoe : 3230 psi (0.85 psi/ft Equivalent Mudweight)

BHA : Bit : 12 1/4"

Drillcollars : 400 ft of 9" x 2 13/16"

Drillpipe : 5", 19.5 lb/ft

1. Calculate and discuss the following :

1. The type of fluid that has entered the wellbore ?

1. The mudweight required to kill the

(8)

VOLUMETRIC CAPACITIES

Drilling Tutorials 2011

Ex. 3 Intermediate Casing Design

You are required to calculate the burst and collapse loads on the 13 3/8” intermediate casing for a gas development well on the basis of the following data :

Drilling Tutorials 2011

Ex. 4 Production Casing Design

You are required to calculate the burst and collapse loads on the 9 5/8" production casing string for a gas development well on the basis of the following data :

Drilling Tutorials 2006

Ex.6 - Cementing

The 13 3/8” intermediate casing string of a well is to be cemented in place with a two stage cement job. The details of the job are as follows :

Cement stage 1 (4300-2800 ft.)

Class 'G' + 0.2% D13R (retarder) : 15.8 ppg

Yield of Class 'G' + 0.2% D13R : 1.15 ft3/sk

Mixwater Requirements : 0.67 ft3/sk

Cement stage 2 (1450-950 ft.)

Class 'G' + 8% bentonite + 0.1% D13R : 13.2 ppg Yield of Class 'G' + 8% bentonite + 0.1% D13R : 1.89 ft3/sk Mixwater Requirements : 1.37 ft3/sk

1. Calculate the following (See Attachment 1 for capacities):

1. The required number of sacks of cement for the 1st stage and 2nd stage of the job (Allow 20% excess above calliper in openhole).
2. The volume of mixwater required for each

• The displacement volume for each

(12)

VOLUMETRIC CAPACITIES

Solution - Cementing Tutorial

Drilling Tutorials 2011

Ex. 5 Directional Well Planning

Using the following data, design a deviated well using a build and hold trajectory.

TVD Target 9700 ft

Horizontal Departure of Target 2400 ft

KOP 1500 ft

BUR 2 degrees/100 ft

Determine the following :

• Tangent
• Along Hole Depth at the end of the Build up Section
• True Vertical Depth and Horizontal departure of End Build up Section
• Along Hole Depth at

Drilling Tutorials 2011

Ex. 6 - Directional Surveying

Whilst drilling a deviated well to a target at 9800 ft. TVD. The following data is recorded at station No. 37 (The target bearing is 60o)

Calculate the North and East co-ordinates, TVD and vertical section of station No. 37 using the average angle method.