Repair of Oil-and-Gas Wells
Oil (gas) well is designed for opening the gas reservoir, by extracting gas from it, injection of the produced gas into underground storage for its subsequent extraction. This type of well is divided into:
- Output wells: gas, oil and gas condensate production;
- Piezometric: research and observations in order to determine the structure of the reservoir, reservoir fluids, and other methods of influence on the field;
- Input wells: for the injection (pumping) of water (air, compressed gas) into the reservoir.
Properly designed construction must approach the desired depth of the well according to the project requirements, as well as the implementation of certain project, the system of opening of productive horizons taking into account all the peculiarities of their operation.
The design of the oil (gas) well is chosen according to geological structure of deposits, the climatic conditions, the distribution of thrust due to temperature from the bottom to the mouth, the chemical characteristics of the gas, nature of the opened rocks, the difference in pressure between the layers, the technological operating conditions of wells and other factors.
Construction of oil (gas) well is defined by:
- length and the number of casing strings;
- lifting height of cement behind the technical and operational casings;
- the construction of bottom-hole of a well;
- the type of head of well’s casing.
Oil (gas) well is constructed taking into account the geological and operational characteristics of deposits, such as the depth of deposits, flowrate of gas and / or condensate, reservoir pressure and temperature, properties of fluids, which saturate the producing reservoir.
The construction of wells is selected in accordance with the diameter the casing of gas wells depending on the geological characteristics of the reservoir, well operating conditions, with the rationale by technical and economic calculations, which take into account the gas flowrates and pressure drops in the wells. In the presence of significant deposits within the boundaries of the drilled zone, separate areas are allocated with different values of debit.
Drilling technology includes periodic lifting and lowering of the drill pipe in order to replace the bit. This type of work is the most time consuming of all the activities carried out during the drilling process. These works are accompanied by drilling the main part of the power with drills and pump rotor; draw works and compressors are used in lowering-lifting operations.
Repair of Oil-and-Gas Wells
Repair of the oil-and-gas wells is a prerequisite in the process of installations in the oil and gas industry. A malfunction of the main wells, occurring for many reasons, lead to a significant reduction in its flowrate or to a full cessation of work. The reason for the termination or reduction of production may be due to the failure of the ground or underground equipment, a change of reservoir conditions, the termination of gas supply or power supply, cessation of pumping and transport of the liquid on the surface and other factors.
Therefore it requires immediate repair of oil and gas wells, as for some time idle period take place. The frequency and the relative duration of the repair of oil and gas wells are estimated by some parameters that characterize the organization and technology of oil extraction.
The main thing in the repair of oil and gas wells is the quality of well casing and insulation of productive reservoirs, prevention and / or troubleshooting of underground part of the equipment and / or the wellbore, preventing gas emissions that can lead to even more clogging of the porous medium, and consequently, the subsequent reduction of the reservoir productivity.
“SNK” Company performs the entire range of works on overhaul, maintenance and underground repair of wells, depending on their complexity and character. Besides, during the workover, the complex of measures is applied to ensure the reconstruction of casing integrity, including elimination of flows behind the casing.
To improve the efficiency of these activities, the Company uses self-engineered solution СНК-2 (reverse type emulsion with external hydrocarbon phase), which does not mix with fresh and brine water.
The solution СНК-2 is rather universal and more efficient when used in carbonate and terrigenous reservoirs, which are operated in a diverse range of conditions: a pressure of hydrostatic level, as well as in a range from abnormally low to abnormally high reservoir pressure. This solution is recommended for application with reservoir temperature up to 1000C, and the main killing fluid should have density 2-3 units lower than the density of СНК-2. The amount of the injected composition is recommended not less than 1 m3 / m. This solution is successfully used to kill all kinds of wells.