Well drilling is the process of creating an artificial hole through the ground, usually to produce water for human use. In most cases, the hole is drilled in shallow aquifers, although some deep wells are constructed to tap into deeper underground sources of water.
The main purpose of well drilling is to provide a source of clean, fresh water from the ground. To accomplish this, the well is drilled to a predetermined depth and is sealed off from nearby areas to prevent contamination.
When a drilling contractor is hired to drill a well, he or she will work closely with the client on planning for the well and its construction. This will involve setting back property lines, constructing an onsite wastewater system, and other requirements that the State of Arizona requires. The design of the well will be based on the specific site, geology, and drilling conditions.
A typical well design involves determining the well depth, casing diameters, materials and lengths. Once these parameters are established, other factors such as completion methods and procedures can be decided.
Some of the most important requirements for well drilling are to provide good flow estimates, control drilling, obtain quality formation logging and samples, monitor well borehole temperature, and detect changes in the water quality. The fluids used in drilling should also be able to permit the immediate detection of geothermal fluids, temperature changes and production zone lithology.
In addition, the drilling fluid must be able to provide sufficient lubrication to the bit and mud pump as they work together. This is because lubrication and friction are critical processes in the drilling of wells.
This is especially true for rotary and directional drilling where the motion of the bit and downhole motor must be controlled to produce the desired results. This is a complicated task because it requires modeling of several complex interrelated processes.
The first process is the lowering of a rotating bit into the ground. This is accomplished using a rotary drilling machine, which spins the bit as it slowly lowers into the ground.
Once the bit reaches bedrock, it is then removed from the well and a casing is installed. The casing can be made from many different materials including concrete, sand, clay and polymer.
Another process is the enlargement of the annulus in which the drill string, bit and equipment work. The enlarged area provides a greater space for the circulation of the drilling fluid and enables better lubrication and heat exchange. This heat exchange is a complex process that has many physical properties that change with depth.
These properties depend on the drill fluid and downhole mechanisms, and they affect the flow of fluid through the annulus and subsequently, through the drill string and bit. This is an important problem that can be difficult to model, even with advanced mathematical models.
A number of specialized software programs are available for modeling these processes, most of which can be purchased from the industry or can be downloaded free from online libraries. These applications can simulate the various aspects of well drilling, including torque and drag calculations, circulating temperature prediction, and casing design.