Compared with general solid mineral deposits, there are three distinctive characteristics of oil drilling. First, the drilling object in whole drilling process flows continuously, and oil deposits change all the time that all measures should be taken according to this situation. Therefore, the whole drilling of oil gas filed is a process of continuously understanding and continuously improvement. Second, the miners do not contact directly with mine in general situation. Oil and gas exploration, understanding of oil and gas reservoirs, and various measures to exert influence on oil and gas reservoirs must be carried out on specialized oil logging. Third, some characteristics of oil and gas reservoirs must be recognized in production process, even recognized until the number of wells is large. Therefore, the stage of exploration and stage of drilling often intertwined in a period of time.(see oil and gas filed development planning and design)
In order to develop a better oil and gas reservoirs, it is necessary to fully understand it. To drill a certain number of edge-finding wells, to use physical geography to determine various boundaries of oil and gas reservoirs(oil-water boundary, oil-gas boundary, split fault, sharp-off line etc.) A certain numbers of evaluation wells should be drilled to understand the properties of oil-gas layer(generally taking cores), including changes in reservoir thickness, physical properties of reservoir, reservoir fluids and their properties, temperature of reservoir and pressure distribution etc., conducting a comprehensive study, to get a more comprehensive understanding of oil-gas reservoir. In oil-gas reservoirs study, it is not possible to study only the oil-gas reservoir itself, but also to study the aquifer adjacent and the connectivity between the two(see oil reservoir physics).
Mining, observation and control of oil reservoir are required in oil production, injection and observation. There are three mutual combining process of oil and gas flow. First, oil and gas flow from the oil layer into the bottom of the well. Second, rise from the bottom of the well to the wellhead. Third, from the wellhead to oil collection station, after treatment of separation and dehydration, into the general station of oil and gas, and then transfer out from the mining area.(see oil reserve project)
Logging engineering applies geophysical methods in the wellbore to pass information on the original conditions and changes in the drilled rock formations and oil and gas reservoirs, especially the distribution of oil, gas and water in the reservoirs and their changes through cables to pass to the ground. To comprehensive judge, and determine the technical measures should be taken.(see engineering logging, production logging and saturation logging)
Logging engineering plays an important role in oil gas development. In building an oil and gas field, logging engineering often accounts more than 50% of the total investment. The development of an oil gas field often requires hundreds or even thousands of wells. There are different technical requirements for wells for different purpose such as mining, observation and control, such as production wells, injection wells, observation wells and inspection wells designed to check the effects of washing oil.
It should be ensured that the drilled well has the least pollution to the oil and gas layer, the cementing quality is high, and it can withstand the effects of various underground operations during mining for several decades. Improving drilling technology and management and improving drilling speed are key to reduce drilling costs.(see drilling methods, drilling process, drilling completion)