Drilling

* The use of piezometers
* Piezometer applications
* Installation procedures
The use of piezometers
Measurement of pure water pressure or joint water pressure (as opposed to standing water level) has numerous applications within the geotechnical and mining fields.

Many techniques have been devised to assist in the preparation of plans covering site operations, such as setting up the rig or the casing of the hole. The two planning techniques most helpful for the drillers are:
1. checklists and procedure statements.
2. critical path plans.
When preparing plans, the driller must understand that there are three kinds of work.
1. Productive work: The work that actually produces information or samples, or that which deepens the hole: the work that the client pays for (e.g., penetrating, conducting tests).

The life of the casing string often determines the effective life of a well or access hole. As we have seen, holes are constructed to provide access to some underground feature, to convey fluids underground or to enclose, some subsurface installation
Casing durability is controlled by the forces and influences acting on the casing and by the casing’s ability to withstand these forces or influences.
If a driller becomes aware of the forces that could be imposed and the nature of the environment, both outside and inside the casing, he can plan to achieve the desired casing life by:

When a hole is being drilled to allow installation of instruments, tools or a pump, the first and obvious requirement is that the diameter of the hole is sufficient to allow easy installation.
If the conditions are such that the hole will be cased then the casing must be large enough to permit the easy running of the pump or other items (the hole in this case, must be larger to accommodate the casing.)

One important requirement of any pumping test is the ability to accurately measure the rate or flow from the bore. This can be done in several ways.

Checklists are used in two ways:
1. Checklists provide comprehensive statements, of items required for a particular task. Such lists are prepared by the driller in consultation with other drilling people and are used by the driller to ensure that he has, on site, the correct equipment and materials for each task that he is required to perform. For example, a geotechnical driller could have a check list for the equipment required to conduct an S.P.T.

1. To produce a hole (to a stated depth and size) free of overbreak but certain to allow free insertion or passage o the specified materials.
2. To produce a hole which is stable and wich will remain stable for along as is necessary to allow insertion of the materials.

Due to their lowest cost, mild steel screens may be an attractive alternative. In general, machince-slot (louvre or bridge) pipe-based screens have good life expectancy in nonaggressive water. Mild-steel wire-wound designs:
• may be used for short life wells or where corrosion or encrustation are unlikely (very rare situation)
• may be galvanised for improved corrosion resistance provided that subsequent action does not destroy the zinc-oxide layer (a condition not to be relied on).
• have poor tolerance for noninhibited muriatic acid used in well rehabilitation.

• Equipment overhauls and repair
• The causes of downtime.
• The need for support.
• Getting the right spare parts.
• Ingenuity.
Equipment overhauls and repair

The drive samplers used on light rigs are illustrated in Section 4. All samplers must be driven into a clean stable bottom. In an auger drilled hole, some soils may require the addition of a little water so that the cuttings are picked up. Pressure sands may have to be stabilized.
• by filling the hole with dense mud
• by using the flexible centre plug or other methods as described in Section 4 of Chapter 7.
A standard 63.5 kg(140 lb) hammer or a bumper sub and the rod string, is used to drive the tube until full.