Drilling Processes

The reservoir section is more consolidated and is the main objective to which the well is being drilled, hence the drilling process has to ensure that any productive interval is not damaged. 

As the name implies the company basically rents the rig and crew on a per day basis. Usually the oil company also manages the drilling operation and has full control over the drilling process. This type of contract actually encourages the contractor to spend as much time as acceptable on location . With increased cost consciousness, day rate contracts have become less favoured by most oil companies. 

Drilhng. Glass is dtiUed with carbide or bonded-diamond dtiUs under a suitable coolant such as water or kerosene. Other drilling processes include a metal tube rotating about its axis (core drilling), an ultrasonic tool in combination with an abrasive slurry, or an electron beam. Tolerances less than 0.1 mm are readily obtained with diamond-core drilling and, if required, holes smaller than 25 )J.m-dia can be made with the electron-beam method. 

During normal rotary drilling processes, due to frictional pressure losses, the pressure inside the drill string is greater than that of the outside drill string. The greatest difference between these pressures is at the surface. 

Sophisticated programs and codes are now available to interpret all these data in real time. The result is a more efficient and safer drilling process. 

The factors that influence the rate of penetration during a conventional rotary drilling process are numerous. In general these factors can be classified into five groups. 

As the materials used in drilling processes are produced from depletable mineral resources, there is a continuous upward trend of cost with time. The field engineer must make a detailed cost comparison of materials available within the target cost of the project. The final choice may be a tradeoff between cost and performance. This is because the choice may narrow down to two or more materials with different initial costs and different expected service lives. Transportation costs of selected materials must also be included in the final cost. 

Chemically enhanced drilling offers substantial advantages over conventional methods in carbonate reservoirs. Coiled tubing provides the perfect conduit for chemical fluids that can accelerate the drilling process and provide stimulation while drilling [1471]. The nature of the chemical fluids is mainly acid that dissolves or disintegrates the carbonate rock. 

R. E. McGlothlin and F. B. Woodworth. Well drilling process and clay stabilizing agent. Patent US 5558171, 1996. 

Unconsolidated or weakly consolidated sediments sometimes collapse around the well screen before the filter pack can be installed. This phenomenon is called formation collapse . Formation collapse can occur as a result of the inherently unstable nature of certain sediments or the disruptive nature of the drilling process. Formation collapse is most common below the water table. Although steps can be taken to minimize the amount of collapse, it may not be entirely preventable. The groundwater monitoring plan may need to accept natural formation material as the filter pack for some or all of the screen section. Well development activities (see Section 2.1.6) can be designed to maximize the effectiveness of the formation collapse materials as a filter pack. 

The above model is referred to as the Extended Bourgoyne-Yomg model. Similarly, analysis of combined data from more than two wells is straightforward and it can be done by adding a new variable and parameter for each additional well, A large amount of field data from the drilling process are needed to reliably estimate all model parameters. 

Since the invention of rotary rigs, used for drilling oil and gas wells, scientists have been searching for fluids that will both facilitate the drilling process and provide maximum productivity once the well is completed. There are two prime requisites for all well fluids. These are ... 

Drilling muds are fluids that are pumped into the bore holes to aid in the drilling process. Most are water based and contain barite, hgnite, chrome lignosulfate, and sodium hydroxide [11], but oil-based drilling muds are still used for economic and safety reasons [12]. Used muds can be removed by vacuum trucks, pumped down the well annulus, or allowed to dewater in pits, which are then covered with soil or disposed of by land farming. 

Seed tapes from Ecoflex have to provide sufficient strength in the sowing or drilling process, without damaging the seed or germination. Fertilizer tapes have to release the fertilizer slowly to the roots of the plants. In both cases, Ecoflex tapes can provide good strength and slow release performance. 

Hydrochloric acid is replacing sulfuric acid in some applications such as metal pickling, which is the cleaning of metal surfaces by acid etching. It leaves a cleaner surface than sulfuric acid, reacts more slowly, and can be recycled more easily. It is used in chemical manufacture especially for phenol and certain dyes and plastics. In oil well drilling, it increases the permeability of limestone by acidifying the drilling process. 

Never force a bit through a stopper, but rather let a bit cut into a stopper on its own. It may be necessary to add more beeswax onto a bit while you drill. This addition can be made by extracting the bit from the stopper, pressing the block of beeswax against the bit, then continuing the drilling process. If you force the bit... 

Bromine is also used in drilling wells. Calcium bromide (CaBt2), sodium bromide (NaBr), or zinc bromide (ZnBt2) is added to a well to increase the efficiency of the drilling process. 

Bromine compounds increase the ciency of the drilling process in oil rigs. 

Based on the above brief description of the various treatment methods, it appears that only a flare or an adsorption tower would be teehnically feasible for H2S control. However, none of these control devices would likely be cost effective during the drilling process. Some cost-effective precautionary measures that can be taken to reduce H2S releases include ... 

SECOFOR is an expert system supporting exception management for drilling process failnres dnring geological exploration. 

The hollow-stem auger is mobile and inexpensive to operate. It is capable of drilling approximately 150 feet into unconsolidated material. (Practical experience indicates that 100 feet may be successfully drilled.) The rig is equipped with a removable plug that helps in the drilling process, but that is inserted inside the hollow stem of the auger and is, therefore, easily removable. 

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