When various kinds of blowout anomalies occur during construction (such as serious loss of stratum, increased overflow at the wellhead, gas enhancement or automatic topping of the tubing, etc.), the main treatment methods for the shift staff are:
1 Stick to the job, obey the on-site command, and take various effective measures in a calm and decisive manner to prevent the continued development and expansion of the blowout.
2 Quickly ascertain the cause of the blowout, report to the relevant departments in a timely and accurate manner, and make a record;
3When the underground drilling tool appears to be automatically topped up, it is necessary to seat the hanger as soon as possible, tighten all the top wires diagonally, quickly install the wellhead or blowout preventer, prepare the next step, and pump the appropriate density. Well fluid, increase the pressure of the liquid column in the wellbore, and continue construction after the pressure balance is stable.
4 When it is found that the well fluid in the wellbore is air-immersed and the density is reduced, it is necessary to replace the well-density well fluid of appropriate density in time, and replace all the original wellbore liquids with pure water or degas with fresh water.
2, preventive measures
Various causes of blowouts that may result in downhole operations should be listed as preventive targets in the measures:
1 Preparation of blowout prevention tools: such as working wellheads with semi-sealed and full-sealed blowout preventers as the main body; well control manifolds (including discharge pipelines, killing pipelines, etc.) with throttling manifolds as the main body; Tools (including drilling tools, blowout prevention, single flow, etc.); the killing fluid storage system should have functions such as purification, increased density, raw material reserve, automatic deployment, automatic filling, etc.; can be applied to special operations and out of control after handling accidents. Special equipment and tools (including high-pressure self-sealing, no-pressing pipe string device, fire-fighting facilities, etc.); the construction site must be equipped with communication tools; the brigade-level construction unit should be equipped with emergency engineering vehicles, equipped with various well control tools, etc. .
2 Safety requirements for construction design: For wells with large diameter tools in the well, the design should specify the speed of the lifting tool and the detailed anti-spray measures. It is strictly forbidden to lift the wellbore at high speed.
3 Construction site layout requirements: the well site is leveled without water, the boiler room, power generation room, tool room, duty room, sledge, etc. are placed neatly, the distance from the wellhead and flammable articles shall not be less than 25m; the well field wire erection shall be regular Insulating rubber flexible wire, bare wire is forbidden; the lighting fixture adopts explosion-proof low-voltage safety searchlight, not less than 5m from the wellhead; there should be obvious fireproof and explosion-proof signs around the well site; complete fire-fighting equipment according to regulations, and placed on the upper hand of monsoon direction.
3. Aftercare measures
1 After the blowout is stopped, the wellhead and the blowout preventer shall be further reinforced, and the well fluid of appropriate density shall be pumped to restore the pressure of the wellbore liquid column and balance the formation pressure. Continue to follow the original design requirements to achieve the purpose of workover.
2 Cause the blowout accident during the operation, regardless of the size, carefully analyze the reasons, accept the lesson, and do the aftermath to minimize the loss.
3 Relevant departments and construction units should analyze the cause of the accident, sum up the experience, learn from it, and will record it in detail in order to take the lead in the future.
4 The geological department should carefully analyze the new changes brought by the underground oil and gas layer blowout, and estimate the amount of fluid (crude oil, natural gas , water, sand, etc.) that is ejected from the well, as a reference material for future oilfield development.
5 Investigate the ground pollution caused by the blowout accident: such as the contaminated area and quantity of farmland, houses, trees, etc., damage to equipment and tools, and economic losses; the environmental protection department shall organize the removal of ground environmental pollution and restore the landform.
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