A Development Programme for the Holly Field Well

Technical Report , 2014 , 30 Pages , Grade: A

Engineering - General

In the light of the increasing demands of energy consumption, the new hydrocarbon reservoir exploration has been carried out to improve the energy supply. The Holly Field is an untapped hydrocarbon reservoir which contains oil and gas. According to an investigative report, the reservoir is located from 10,500 ft. to 11,750 ft. below the surface. The data from the Holly Field makes it possible to put together an overview of the design of a well there. This report introduces the basic design element of a well with a special focus on the rotary drilling, the well planning, the hydraulic pressure, the casing design, the bottom hole assembly (BHA) equipment and the well completion. In addition, each section will illustrate a design principle briefly. The aim of this report is to outline a comprehensive development programme for the Holly Field well.

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Table of Contents

1. Introduction ... 4

2. Rotary Drilling ... 5

2.1 Introduction to Rotary Drilling ... 5

2.2 Hoisting System ... 6

2.3 Circulating System ... 6

2.4 Rotating System ... 7

2.5 System Association ... 8

2.6 Selecting a Land Rig ... 8

3. Well Planning ... 10

3.1 Well Planning ... 10

3.2 Pore Pressure ... 10

3.3 Fracture Pressure ... 10

4. Pore Pressure and Mud Weight ... 12

5. Cement ... 14

5.1 Introduction to Cement ... 14

5.2 Lightweight Additives ... 14

5.3 Retarders ... 14

5.4 Accelerators ... 14

5.5 Heavyweight Additives ... 15

5.6 Cement related calculation ... 15

6. Casing Design ... 19

6.1 Purpose of Casing ... 19

6.2 Principle of Casing Selection ... 19

7. Selection of BHA ... 21

7.1 Principle of Selecting BHA ... 21

7.2 Function of Selected BHA ... 21

7.3 Determine the number of drill collars ... 23

8. Well Completion ... 25

8.1 Options for Well Completion ... 25

8.2 BottomtoTop Design ... 26

9. A preview of the well design ... 27

10. Conclusion ... 28

References... 29

Appendix A ... 30

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1. Introduction

Well design involves drilling and mechanical engineering, geology,

hydraulics, and the physical, chemical and material sciences, all of which

epitomises hydrocarbon exploration technology. A completed well has to qualify

in several aspects such as safety, environmental protection, production efficiency

and reasonable cost. Therefore, a comprehensive construction plan has to be

carried out first, which requires practical and theoretical expertise. In addition, a

further data collection process is required to build an integral database for

design reference. However, uncertainty exists in every operation, which should

be emphasized so that the standard procedures are strictly followed.

The aim of this report is to design a new well, namely Holly Field well.

Based on the investigation, there are two reservoirs, gas and oil, located 10,500

ft. to 11,750 ft. below the surface. The main purpose of the Holly Field well is to

develop an oil reservoir, which will define which principles should be undertaken.

This report will demonstrate the basic design of Holly Field well with a brief

design principle illustrated in each section.

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2. Rotary Drilling

2.1 Introduction to Rotary Drilling

Exploration of a hydrocarbon reservoir brings uncertainty and risk to the

drilling operation such as an unforeseen formation influx. The rotary drilling

method has been chosen to implement the Holly Field development programme

because it may provide flexible solutions for unpredictable situations. Rotary

drilling developed in the early 1800s and today is the most common way of

exploring for hydrocarbon reservoirs (Bourgoyne Jr. et al. 2003). A rotary drilling

rig normally consists of hoisting, circulating and rotating systems. Each system

has a different function, and they achieve a complete cycle of drilling operation

by working in association. The following are brief introductions to each system.

Fig. 2a. The rotary drilling process (Source: Applied Drilling Engineering)

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2.2 Hoisting System

In simple terms, the hoisting system manipulates the position of the

drilling equipment, including the drill strings and casing strings. The hoisting

system not only lowers and raises the drilling equipment but also contributes to

replacing equipment or adding extended parts. The basic structure of the

hoisting system consists of a derrick (or mast), travelling block, crown block,

drill line, and hook and draw work, which are shown in Fig 2b. (Bourgoyne Jr. et

al. 2003). The derrick is the main frame of the hoisting system and provides the

working space for the hoisting operation. The travelling block, crown block, drill

line, and hook and draw work contribute to a motion system to control the

position of the drilling equipment.

Fig. 2b. Schematic of block and tackle (Source: Applied Drilling Engineering)

2.3 Circulating System

The main function of the circulating system is to keep the hole clean

during the drilling process. The circulating system cleans the hole by moving the

rock cuttings to the surface. To improve its ability to carry cuttings, drilling mud,

which is a kind of suspension clay normally mixed with water, is commonly used

in this process as a circulating fluid (Bourgoyne Jr. et al. 2003). The circulating

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system consists of mud pumps, mud pits, mud mixing equipment and

contaminant-removal equipment (see Fig 2c). In addition, the cuttings can be

flushed to the surface to provide samples for the logging geologist to analyse.

Fig. 2c, Schematic of example rig circulating system for liquid drilling fluid

(Source: Applied Drilling Engineering)

2.4 Rotating System

The rotating system is a power source that drives the drilling bit rotation.

The rotating system is mainly composed of swivel, kelly, rotary drive, rotary

table, drill pipe and drill collars (see Fig 2d) (Bourgoyne Jr. et al. 2003). The

kelly, also called the lower rotating system, is the main equipment that provides

rotating force to the drill string. In addition, there is another type of rotating

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system, namely the top rotating system (power swivel), that is attached to the

travelling block.

Fig. 2d. Schematic of rotary system (Source: Applied Drilling Engineering)

2.5 System Association

The three aforementioned systems are the basic shape of a rotary drilling

rig. First, the hoisting system puts the drill string into position. Then the rotating

system and the circulating system are activated together to execute the drilling

process and keep the path clean simultaneously (EM201 Course Note b).

However, the drilling process in exploring a hydrocarbon reservoir can be

complicated. These three systems have to cooperate and compensate for each

other for the duration of well development.

2.6 Selecting a Land Rig

The composition of a land rig depends on local circumstance. However,

several conditions could provide the primary considerations, such as the whole

budget of the exploration, the purpose of the well, the location of the well, the

formation environment of the well, the reservoir type and the depth of the well

(Aadnøy 1999). In the case of the Holly Field well, the criteria for selecting the

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rig should include following points. The Holly Field well is a land reservoir with

two kinds of reservoirs, gas and oil. Therefore, it is inevitable that the rig will

encounter gas formations during the drilling process, which means monitoring

the formation environment is crucial. In addition, the main purpose of the Holly

Field well is to produce an oil reservoir with a total depth of 12,000 ft.

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3. Well Planning

3.1 Well Planning

In planning the well, two essential factors should be taken into account:

pore pressure and fracture pressure. During the drilling process, the wellbore

pressure should be kept equal to or higher than the naturally occurring pressure

of the formation's fluids and the maximum wellbore pressure that the formation

can tolerate without breaking (Aadnøy 1999). Before the drilling operation

starts, the big picture of pore and fracture pressures should be predicted by the

evidence from previous wells, theory and field measurements.

3.2 Pore Pressure

Pore pressure, called formation pressure, is the pressure that exists in the

pore space and is revealed by the fluids contained in the pore space (King

1988). During the drilling process, the production of oil frequently changes the

reservoir pressure and influences the permeability inside the rock. If the pore

pressure is higher than the wellbore pressure, the formation fluid might enter

the drilling pipe and pollute the production oil, possibly inducing a blowout.

Therefore, monitoring pore pressure is one of the essential routines. Two

methods used to predict pore pressure before drilling are seismic data and data

from nearby wells. A geophysicist can analyse the seismic data to reveal the

formation profiles. However, the most accurate data might be directly measured

from the field. While the drilling is in progress, continuous logging procedures

are executed to ensure that pore pressure is under control.

3.3 Fracture Pressure

Fracture pressure, also called working pressure, is related to the pressure

of the drilling fluid or of the cement slurry (King 1988). During the pumping of

the drilling fluid into the well, the hydrostatic pressure of the drilling fluid may

have a detrimental effect on the formation. A formation breakdown gives rise to

an unstable environment, which may cause the drilling fluid to lose circulation.

In other words, wellbore pressure higher than the fracture pressure means that

the drilling fluid may run into the formation faults or other more penetrable

formations. As a result, the drilling fluid loses the ability to maintain constant

wellbore pressure, and the well may collapse. There are several methods of

predicting fracture pressure, but the Hubbert and Willis equation, which provides

• College: Robert Gordon University Aberdeen (Engineering)
• Course: Oil and Gas Engineering
• Grade: A
• Author: Chia Lin Lin (Author)
• Publication Year: 2014
• Pages: 30
• Catalog Number: V300527
• ISBN (eBook): 9783668619647
• ISBN (Book): 9783668619654
• Language: English
• Tags: development, programme, holly, field, well