Drilling engineering Assignment Question

HERIOT-WATT UNIVERSITY
INSTITUTE OF PETROLEUM ENGINEERING
MSC/DIPLOMA COURSE DEGREE  EXAMINATION IN PETROLEUM ENGINEERING

Section A

A3.Draw and Labelthe component parts of the hoisting system on a conventional land drilling rig.[4]

A2. Describe how the length of Drillcollar used in the BHA of a drillstring is calculated. [4]

A3.List and describe three indicators, other than the “d” exponent, which might suggest that an over pressured shale had been encountered.[3]

A4.Describe the effect of tensile loading on the burst and collapse rating of casing.[4]

A5. Describe the main factors which influence the pressure loss when circulating fluid through the drillstring and annulus when drilling? [6]

A6.Describe the principal functions of the following casing strings:

Surface Casing

Intermediate Casing [6]

A7. The results from a Leak off test which has been conducted below the 9 5/8” casing shoe of a well are presented below.

TVD of 9 5/8" Shoe : 6500 ft. Mudweight in hole : 10 ppg

Vol. pumped bbls

Surface Pressure psi

0.5 30

1.0 110

1.5 205

2.0 295

2.5 390

3.0 475

3.5 570

4.0 655

4.5 760

5.0 800

5.25 820

Calculate the MAASP for the subsequent hole section when the mud weight is 11ppg [4]

Section B

B1 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

1. The volume of mud required to complete stage 1 of the well killing operation (assuming that the one circulation method is used)

[11]

1. Briefly explain the essential differences between the 'one circulation method' and the drillers method for killing a [4]

1. Briefly describe the principal types of BOPs which are used on a well and the way in which they are configured in a BOP stack [6]

1. In the case of a gas influx, why must the well killing operation be started as soon as possible? [2]

B2 The 9 5/8” production casing of a gas development well is to be designed using the following data :

Top of Production Packer : 7200 ft

Formation Fluid Density : 9 ppg

Expected gas gradient : 0.115 psi/ft Depth of Production Interval (TVD) : 7350-7750ft Max. expected pressure in

production interval : 3700 psi

Packer fluid density : 9 ppg

Design Factors (burst) : 1.1

(collapse) : 1.0

Note : Gaslift may be used at a later stage in the life of this well.

1. Calculate the burst and collapse loading which will be used in the selection of casing for the production casing [8]

1. Explain the logic behind the criteria used in your casing design

[3]

1. Describe the impact of tension on the design of the casing

[4]

1. Describe the principal functions of the following casing strings:

conductor; surface; intermediate; and production casing.

[8]

B3. The 13 3/8” intermediate casing string of a well is to be cemented in place with a single stage cement job. The details of the job are as follows :

Previous Casing Shoe (20") : 1800 ft

13 3/8" 72 lb/ft Casing Setting Depth : 5100 ft 17 1/2" open hole Depth (Calipered @ 18" average) : 5130 ft Mudweight in hole when cementing

operation is performed : 12 ppg

Shoetrack : 80 ft

Cement stage 1 (5130-3300 ft.)

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

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

Mixwater Requirements : 0.67 ft3/sk

1. Calculate the following (See Attachment for capacities):
   • The required number of sacks of cement for the job (Allow 20% excess in open hole).
   • The volume of mixwater required for the
   • The displacement volume for the

[12]

1. Calculate the static bottomhole pressure when the top plug is bumped on the float collar at the end of the above cementing [2]

1. Describe the functions and properties of a spacer when used in the cement operation? [3]

1. Describe the principles of operation of the CBL/VDL

[6]

B4.

• Describe, with the aid of diagrams, the Tangential and Balanced tangential mathematical models used to describe and calculate the trajectory of a

[4]

• Whilst drilling a deviated well to a target at 11000 ft. TVD. The following data is recorded at station No. 37 (The target bearing is 132 degrees)

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

[12]

1. Describe (using diagrams) the major differences between the equipment used for a “steerable” drilling BHA and a more conventional directional drilling BHA using a bent sub and mud [4]

1. Describe the issues that would be considered when selecting the inclination of the tangent section when designing a deviated [3]

End of Paper

Attachment I

VOLUMETRIC CAPACITIES