5. Drilling programme

This programme is a detailed step by step procedures for drilling the well. It is divided into a number of sub-programmes:-

1. Casing and cementing programme

This programme specifies the type and length of the casing required for each hole section. This will be discussed later in detail at “Casing and Cementing”. There you will see that casing can be subjected to tremendous loads. By anticipating the maximum loads which can be imposed on the casing, the required strength and steel qualities can be determined and specified.

The programme will also specify the type and consistency of cement to be used to bond the casing to the drilled hole. In addition, any additives which may be required will be indicated.

2. Bits and Hydraulics programme

This programme will specify the type of bits, nozzle sizes and mud circulation rates for each section of the hole.

3. Mud programme

The mud programme specifies the mud properties which must be maintained during the drilling of each phase of the well.

4. Drilling procedures programme

This programme gives instructions to the drilling contractor and operating company representatives regarding procedures to be followed.

The type of information which may be included in such a programme include :

• Bottom hole assemblies to be used.

• Equipment inspection procedures.

• BOP testing procedures.

• Suggested remedies for expected hole problems.

• Drilling parameters like rotary speeds (RPM), weights to be used on bits (WOB) ...etc.

Drilling a well costs a considerable amount of money. Proper advance planning however can control this expenditure. This is why the drilling programme is such an important part of the process of making a hole.

2.RIG TYPES & COMPONENTS

6. LAND RIGS

Land rigs vary considerably in size, lifting capacity, power generation, ability to circulate fluids... etc. See figure 01 below for an example of a land rig.

1. OFFSHORE RIGS

1. JACK-UP RIGS

A Jack-up rig is a movable platform that can be jacked up and down three or four supporting legs. It supports drilling in relatively shallow water depths (down to 400 feet). To move rig between close locations the platform is lowered down the legs till it floats then the legs are jacked up to the maximum height. The whole rig can then be towed by means of two boats. In long rig moves or across oceans the whole rig is normally carried on a huge carrier.

Jack-up rigs are the most utilized type of rigs nowadays. Recently, legs design has been modified to support drilling in deeper waters. See figure 02 below.

Figure 02

The following lists some advantages and diadvantages of the Jack-up rigs:

Advantages

1. Provides a fixed platform at low initial cost.

2. Can operate in soft bottom deltas.

3. Can withstand storms.

4. Does not need marine risers or sub-sea stack.

Disadvantages

1. Poor safty records.

2. Difficult to tow.

3. Has moving parts in jacking mechanism.

4. Hazardous for going on and off locations