Oil Wells Repair

Oil wells repair includes measures for prevention of troubles and/or troubleshooting of underground and/or wellbore equipment.

When gas and oil wells are operated, there is a possibility of various troubles associated with the wells directly, and with the relative underground facilities.

Appropriate actions should be performed to prevent the troubles, which often can lead to disturbances and even to the wells shutdown.

Basically, they are preventative: their implementation is carried out in accordance with a special schedule.

When performing repair works caused by prolonged wells downtime, operating ratio should be taken into account, defined as the ratio between the actual work of each well and the relative calendar operation period with gradation by month, quarter, year.

“SNK” company offers all the existing options of wells repair:

Oil wells repair is characterized by the following groups of maintenance

1. Preparation: the arrival of the brigade atan accident zone, killing production wells, placing the equipment in the wellhead and its installation, dismantling of the wellhead equipment;
2. Repair work: performance of lowering lifting operations;
3. Final work: assembly of the wellhead equipment, start the well performance, its commissioning, instruments and equipment cleaning from any contamination, as well as dismantling and cleaning of the working area.

Sand plugs and sand production can appear during oil extraction and oil wells repair, if the bottom-hole zone consistsof weakly cemented rocks, which leads to faultsduring the well operation, shutdown or a dead stop of oil supply. Blockages are formed in production casing and tubing. In some cases, their amountcan exceed several hundred meters. To delete them, a variety of methods are used, for example, bailer, lowered on a rope, where the winch is released 10-15 meters before the plug, as a result, the valve is opened, and a certain amount of sand enters the bailer. When the bailer is raisedits valve is closed, and the bailer liberated on the surface is again lowered into the well.

“SNK” company offers all the existing options of wells repair:

• Provision by special equipment, when placing a well on production(entry flowing, gas-lift wells, equipped with ESP and rod pump);
• Conversion of oil well to another way of use (flowing to gas-lift, rod pump, ESP; gas-lift to rod pump, ESP; rod pump to ESP; rod pump to dual completion, etc.)

• Cleaning and washing the bottom and the wellbore (hot oil with the addition of surfactants, wellbore treatment with reagents - CКO, TГXB, ГКO)
• Flowing wells repair (checking, replacement, hydraulic-pressure test, sealing and restoration of wellhead equipment).
• Performance optimization (improving the depth of the suspension; and changing rod pump and ESP size);
• Repair of wells equipped with ESP, EPCP, EDP;
• Assembling the wells are equipped with rope pump (checking and replacement of the pump, the elimination of rods separation; change, hydraulic-pressure test, sealing; change of the polished rod, cleaning and steaming; wellhead treatment).

Overhaul 1, Set-up and Insulation

• Stop of watered intervals, as well as some of the layers with polymers and cement;
• Restoration or build-up of the cement sheath.

Overhaul 2, Sealing of the Casing

• plugging;
• cladding;
• penetration of extra casing with a smaller diameter;
• partial replacement of the column.

Overhaul 3, Elimination of Accidents Occurred during wells Servicing or Operation

• removal of underground equipment as a result of the accident;
• cleaning the bottom-hole from foreign objects;
• fixing and replacement of the damaged part(s) of the column, the repair of the wellhead;
• restoration works after pipes and rods collapse, breaking the wireline;
• other work.

Overhaul 4,Insulation of Productive Horizons with a Return to Higher and Lower Horizons, Zonal Isolation

Overhaul 5, The Implementation or Removal of Packer-Strippers;

Overhaul 6, Complex or Drilling Activities

• drilling of a newly created bore;
• drilling of new bores in order to identify additional productive capacity of boreholes having an increased flooding and/or a low productive characteristics;
• drilling of cement column;
• milling of the casing shoe by advancing borehole in the rock environment.

Overhaul 7, Additional Surface Treatment of Bottom-Hole Zone

• hydrolyzed polyacrylonitrile acid treatment (HPAT)
• hydraulicjetperforation (HJP)
• hydraulic fracturing of reservoir (HFR)
• vibratory processing of bottom-hole zone
• thermal-gas-chemical treatment (TGCT and others)
• thermal treatment of bottom-hole zone
• Other works

Overhaul 8, Wells Survey

• filling and development of reservoirs
• detailed geological section
• assessment of technical conditions

Overhaul 9, Wells Transition to Operation in Different Purposes

• wells development for input purpose
• wells transition to the ones for technical water selection
• Wells transition to piezometric, observational ones

Overhaul 10, Conservation/re-entry of wells using:

• Cement plugs
• parkers.

Overhaul 11, Abandonment of wells, including with the installation of liquidating plugs

Overhaul 12, Other Overhaul Measures