Oil drilling is divided into exploration wells and production wells according to the purpose of drilling. According to the well trajectory can be divided into vertical wells and directional wells. According to the environmental conditions of drilling operations, it is divided into onshore drilling and offshore drilling. According to the well depth, it can be divided into shallow well, medium-deep well, deep well, ultra-deep well, ultra-deep well and so on. Next, everyoneOil drilling rig manufacturersLet's take a closer look at the small series.
1. exploration and production wells
(I) exploration well
Exploration wells are wells drilled for the purpose of obtaining geological data, including geological wells, pre-exploration wells, detailed exploration wells, evaluation wells, etc. Exploration wells are generally vertical wells.
(1) Pre-exploration wells: refers to wells drilled for the discovery of oil and gas reservoirs in favorable circles determined by seismic detailed investigation and comprehensive geological research, including wells drilled for the discovery of new oil and gas reservoirs in known oil fields.
(2) Detailed exploration well: refers to the well drilled in the discovered oil and gas circle to find out the oil and gas boundary and reserves, and to understand the structure of oil and gas layer and oil production capacity.
(3) Evaluation well: refers to the well drilled to find out the oil and gas-bearing area and geological reserves of the trap after the discovery of the oil and gas-bearing reservoir in the pre-exploration well.
Due to the unknown formation conditions and the need to take cores and geological data, it takes a long time and costs a high cost to drill exploration wells. Movable drilling units are generally used to drill exploration wells offshore.
(II) production well
Production wells, also known as development wells, are wells drilled for oil and gas production in the oil field development stage, including oil (gas) wells, water injection (gas) wells, adjustment wells, etc. Generally, no core is taken when drilling production wells, the formation conditions are clear, the drilling speed is fast, and the cost is low.
(1) Oil (gas) wells: In the development of oil fields, the wells drilled for the exploitation of oil and natural gas can be divided into oil production wells and gas production wells.
(2) Water injection (gas) wells: in order to improve the recovery rate of oil fields for water injection, gas injection, to supplement and rational use of formation energy drilled wells, but also can be divided into positive injection wells (from the tubing to the formation of water injection wells) and reverse injection wells (from the casing to the formation of water injection wells).
(3) Adjustment wells: on the basis of the original well network, some scattered wells or encrypted wells in batches are drilled to improve the effect of oil field development.

2. directional well
In oil drilling, in addition to vertical wells, according to certain purposes and requirements, wells drilled along the design trajectory are called directional wells, including horizontal wells and deviated wells. With the development and improvement of drilling technology, in order to meet the needs of oil and gas field exploitation, since the 1990 s, highly deviated wells, horizontal wells and large displacement wells are the direction of development.
(I) horizontal well
Horizontal well refers to the design. The inclination angle of the large well is between 86 ° and 120 °, and a certain length of the well is drilled along the (near) horizontal direction. Horizontal well technology has been developed since the 1990 s because horizontal wells can increase the exposed area of the developed oil layer, increase the oil production of the oil layer and the recovery rate of the oil field. Horizontal wells can be divided into long, medium, short, short four kinds of curvature radius. Horizontal well drilling is relatively difficult, most of which require special equipment, drilling tools, tools, instruments and special processes.
(II) slope well
Deviated wells are designed. Wells with large well inclination angle not more than 85 ° can be divided into low-angle well, medium-angle well and high-angle well, among which medium-angle well is used more frequently.
(III) cluster well
During the development of oil fields, due to the limitations of ground and environmental conditions, as well as the requirements of rational use of land resources, it is often necessary to drill several or dozens of directional wells and a vertical well in a planned way on a well site or platform. These wells are collectively referred to as cluster wells. The distance between wellheads of cluster wells (well spacing) is generally 2~3m. Cluster wells can reduce the construction cost of well site or platform, and facilitate the production management of oil wells, which is widely used in offshore oil field development.
3. deep and ultra-deep wells
According to the well depth (H), oil wells are divided into shallow wells (H≤ 2500m), medium-deep wells (2500m9000m).