Most of the work that is needed to commission the wells involves the launching of deep pumps, compressor pipes, and pump rods. In the process of their activities, various breakdowns can occur. Regardless of the method of operation (compressor or pump), in the event of a malfunction, the pressure drops sharply or the fluid supply completely stops. Depending on the degree of complexity of the breakdowns, the resumption of full-fledged activities requires ongoing and overhaul of wells.
Restoring normal operation is associated with lifting equipment from underground to the surface for repair, eliminating breaks and unscrewing of sucker rods. An important role is played by cleaning sand plugs by flushing or bailer.
Well repair due to a violation of their technological mode of operation includes:
- replacement of tubing with analogues of a different diameter;
- change in the length of the lifting pipes;
- elimination of breakage of rods;
- wellhead equipment replacement;
- installation of electric centrifugal pumps.
But this is not a complete overhaul of the wells. All these works are related to current activities. They are carried out by special teams that deal with the underground elimination of breakdowns. Overhaul of wells is a more complex and large-scale event. These include:
- elimination of accidents associated with breakdowns of the casing string (crushing or breaking);
- drainage of water that appeared in the well;
- work related to the transition to another horizon;
- catching broken cables, pipes, tart cables and other equipment.
Overhaul of wells is carried out by special teams. The main task of the personnel who are engaged in ongoing work, and other field workers is to help reduce the time of these activities and maximize the uninterrupted service life of the well during its operation. The overhaul period is the duration of the actual normal operation of the equipment, that is, the period between two scheduled repairs.
To increase the intervals of this time, properly performed underground and overhaul of wells is extremely important. To ensure uninterrupted operation, ground and underground activities are combined. Schedules of such events are prepared in advance at the fields.
Based on the ratio of the actual time of productive work to the total number of calendar days in a certain period (quarter, year, etc.), an indicator such as the operational coefficient is derived. Its value is always less than one. On average, in oil and gas production enterprises, it ranges from 0.94-0.98. That is, 2-6% of the time is spent on various types of repair activities.
The crews that carry out routine repairs, as a rule, include three people: an operator at the mouth, his assistant and a tractor driver driving the winch. Usually they work on a rotational basis. Overhaul of wells is carried out by special teams that are part of various service departments and enterprises of gas and oil companies.