RU2423599C2 - Procedure for repair operations in well - Google Patents

Abstract

FIELD: oil and gas production.

SUBSTANCE: procedure consists in well killing, in lifting production string - PS with downhole equipment to surface, in examination of string for detection of interval for leakage, in installation of packer on string, in lowering string with downhole equipment, in pumping plugging composition under pressure and in putting well in operation mode. As plugging composition there is used waterproofing or hydrophobic liquid not changing its aggregate condition under operation mode. A packer is installed at a level below interval of leakage of a casing string, while plugging composition is supplied into space above the packer between the casing string and production string at constant pressure. When supply resisting pressure rises above allowed, supply is stopped.

EFFECT: raised reliability of isolation of leakages and facilitating repair in place of leakage in casing string.

2 cl, 10 ex

Description

The invention relates to the oil and gas industry and is intended to eliminate leaks in the casing of gas and gas condensate wells.

There is a method of repair and insulation work in a well by eliminating leaks in the casing string and flows behind it using hardening materials, for example resins (“Instructions on the technology for eliminating leaks in casing and casing flows in drilled and producing wells using alkylresorcinol and epoxyphenol resins (AEFS ), RD 39-2-247-79, Moscow, VNIIBT, 1979, p. 10-19).

The disadvantage of this method is the low efficiency due to the rapid loss of insulating properties of the material used, the high cost of the material used, as well as the need to comply with increased safety measures.

There is a method of repair and insulation work in a well, according to which the calculated amount of cement is pumped through the tubing string, lowered into the casing leakage interval, and the tubing string is raised to a height corresponding to the upper cement mortar boundary, and due to the reverse circulation of the displacement fluid is “cut off” the cement slurry in order to prevent the tubing string from sticking and to reduce the cement cup after drilling of cement solidification (Ametov IM, Sherstnev NM Application of composite systems in the industrial exploitation operations wells -. M .: Nedra, 1989, 130.).

The disadvantage of this method is the low reliability of isolation of leaks in the casing, since there is mixing of the cement mortar and squeezing fluid.

A known method of carrying out repair work in a production well, including injecting into the well the estimated volume of viscoelastic composition, subsequent pumping of cement mortar through the tubing string at the open annular space of the well and injecting the estimated amount of displacement fluid at the closed annular space of the well, lifting the tubing string pipes and exposure until the material reaches the required properties. The estimated volume of the viscoelastic composition is pumped into the well through the tubing string and placed in an interval below the lower boundary of the casing leakage, and the tubing string is raised to its lower open end at the casing leakage level before cement injection and above the upper boundary of the cement mortar - after injection, while before the injection of cement mortar do technological exposure, and the estimated amount of selling liquids are chosen equal to 1.5 times the volume of the part of the tubing string in the cement mortar (RF patent No. 2121559, 1998).

The known method does not provide durable sealed material in the field of repair work and, as a result, does not provide the desired degree of sealing.

The closest to the invention in technical essence and the achieved result is a method of repair and insulation work in the well, including killing the well, raising the surface of tubing with tubing equipment, examining the casing string, identifying the casing leakage interval, installing Tubing of the packer, descent into the well of tubing connected to the downhole equipment using couplings, injection of a curable blocking compound into the well under pressure and well injection in operating mode (RF patent No. 2170333, 2001).

However, this method has a number of significant disadvantages. The injection of a curable blocking composition does not allow removing the packer and raising the tubing in the future, which significantly limits the possibility of further work at the well, for example, washing the face, eliminating underlying leaks, and intensifying operations. In addition, the hardened composition does not adequately seal leaks and leaks, stresses arise in the sealing plugs and equipment, which can lead to cracking and further leakage.

The problem to which the invention is directed, is to increase the reliability of isolation of leaks and to ensure the possibility of repairing leaks in the casing string, both inside and in the annular space of the casing.

The technical result consists in increasing the degree of sealing of the defective zone of the casing without losing the maintainability, operational reliability and reducing the time to commission the well in the Far North.

The specified technical result is achieved in that a hydrophobizing or hydrophobic liquid is used as the blocking composition, which does not change its state of aggregation under operating conditions, while the packer is placed at a level below the casing leakage interval, and the blocking composition is fed into the over-packer space between the casing and tubing at constant pressure, and stop the flow when the pressure of the flow resistance is higher than permissible.

As a low-freezing hydrophobic liquid, stabilized gas condensate, degassed, low-viscosity oil (viscosity less than 100 mPa · s), used machine, transformer or turbine oil or mixtures thereof are used, and as a hydrophobizing liquid, solutions of hydrophobizing agents in a hydrophobic liquid selected from the group: Neftenol ADB, heating oil, highly viscous degassed (viscosity of more than 100 MPa · s) oil, oxidized oil.

These distinguishing features are significant. During the tests, it was found that the placement of the packer on the tubing is lower than the casing failure interval, and filling the above-packer space between the casing and tubing above the leakage level completely isolates the leakage interval and eliminates the influence of the casing leakage interval on the well operating mode.

The injection of a low-freezing hydrophobic or hydrophobic fluid into the annulus after fixing the packer prevents water from entering the over-packer space from casing leakage due to the creation of a hydrophobic barrier to its movement. The supply of fluid at constant pressure ensures the penetration of the sealing compound into all cracks and cavities, including annular voids. Increasing the pressure of the injection resistance indicates sufficient filling and gives a signal to stop feeding, in order to also prevent an increase in the load on the equipment and the packer. Due to the fact that the sealing plug is constantly in a liquid state, maintainability is maintained, the risks of new cracks appear, and the possible occurrence of new voids or leaks is prevented by the flow of hydrophobic liquid into them.

Unlike the prototype, the claimed method does not use curable blocking compositions. If necessary, the underground equipment, tubing and packer can be removed with minimal effort from the well and necessary work can be done, for example, to install a cement bridge that cuts off the flooded formation, flushing the bottom of the sand, operations to intensify the work of the well.

In contrast to the commonly used water-based curable blocking compositions (cement, grouting and gel-forming polymer compositions, curable resins, sediment and gel-forming compositions based on liquid glass, etc.), low-freezing water-repellent or hydrophobic liquid can be used at low negative temperatures without special technological measures.

The application of the proposed method will significantly reduce the repair time and costs of its implementation, increase productivity.

The method is implemented as follows.

First, killing the well, lifting to the surface of tubing (tubing) with downhole equipment and examining the casing are carried out. As a result of the inspection, the casing leakage interval is revealed. Next, a packer is installed on the tubing below the casing leakage interval. During the descent of the tubing tubing screwed with the help of couplings with downhole equipment into the well, the tubing tubing connections above the packer installation site are coated with a sealing compound. After the descent of the specified arrangement, the packer is fixed at a level below the detected casing leakage interval and below the closure of the connecting sleeve to the casing leakage zone. The blocking composition is injected into the space above the packer between the casing and tubing. Moreover, as a blocking composition, a low-freezing water-repellent or hydrophobic liquid is used that does not change its state of aggregation in the temperature range from surface to formation in the leakage interval. The injection is carried out at constant pressure to a level above the leakage interval. Stop feeding when the injection pressure rises above the allowable feed pressure.

As a low-freezing hydrophobic liquid, stabilized gas condensate, degassed, low-viscosity oil (viscosity less than 100 mPa · s), used machine, transformer or turbine oil or mixtures thereof are used, and as a hydrophobizing liquid, solutions of hydrophobizing agents in a hydrophobic liquid selected from the group: Neftenol ADB, heating oil, highly viscous degassed (viscosity of more than 100 MPa · s) oil, oxidized oil.

Method implementation examples

Example 1

After rising to the surface of tubing (tubing) with downhole equipment, a casing inspection is carried out. As a result of the inspection, the casing leakage interval is revealed. Below the casing leakage interval, a packer is installed on the tubing. Threaded tubing connections above the packer installation site are coated with a sealant. Then the whole arrangement is lowered into the well, while the packer is fixed below the detected casing leakage interval and below the closure of the connecting sleeve closest to the casing leakage zone. A stabilized gas condensate with a density of 720 kg / m ^{3 is} pumped into the space above the packer between the casing and tubing. Moreover, the injection is carried out to a level above the leakage interval. Stop the flow when the pressure of the injection is increased above the permissible feed pressure, determined by the strength characteristics of the casing.

Example 2

The tubing preparation before injection of the blocking composition is carried out as in example 1. As a blocking composition, degassed low-viscosity oil with a viscosity of 62 MPa · s is used. Stop the flow with increasing pressure to a level determined by the strength characteristics of the casing.

Example 3

Preparatory operations before the injection of the blocking composition is carried out as in example 1. As a blocking composition, used engine oil with a viscosity of 150 MPa · s is used. Stop the flow with increasing pressure to a level determined by the strength characteristics of the casing.

Example 4

The method is implemented as in example 1, but as a blocking composition used waste transformer oil with a viscosity of 112 MPa · s. Stop the flow with increasing pressure to a level determined by the strength characteristics of the casing.

Example 5

The implementation of the method is carried out as in example 1. As a blocking composition used waste turbine oil with a viscosity of 86 MPa · s. Stop the flow with increasing pressure to a level determined by the strength characteristics of the casing.

Example 6

The method is carried out as in example 1, but a mixture of used machine, transformer and turbine oils, taken in equal proportions, is pumped into the well. The mixture has a viscosity of 97 MPa · s. Stop the flow with increasing pressure to a level determined by the strength characteristics of the casing.

Example 7

The method is carried out as in example 1. As a blocking composition, a solution of Neftenol ADB in gas condensate is used. The solution is prepared by mixing these ingredients in a ratio of 1:20.

Example 8

The method is implemented according to example 1. As a blocking composition, a solution of heating oil in used transformer oil is used with a ratio of ingredients of 1:10.

Example 9

The method is carried out as in example 1. As a blocking composition, a solution of degassed high-viscosity oil with a viscosity of 120 MPa · s in used turbine oil is used with a ratio of ingredients of 1:20.

Example 10

The method is carried out as in example 1, but as a blocking composition using a solution of oxidized oil with a viscosity of 355 MPa · s in degassed low-viscosity oil with a viscosity of 26 MPa · s with a ratio of components of 1:20.

The proposed method has high reliability, as it guarantees the isolation and repair of leaks in the casing string, both inside and in the annular space of the casing string, due to the penetration of hydrophobic fluid through the casing leakage. It also greatly facilitates and accelerates work in the Far North, reduces the time for the commissioning of the well.

Claims (2)

1. A method of carrying out repair and insulation work in a well, including killing a well, raising tubing pipes to the surface — tubing with downhole equipment, examining the casing string with an interval of leakage, installing a packer on the tubing, launching tubing with downhole equipment, injection blocking composition under pressure and putting the well into operation, characterized in that a hydrophobizing or hydrophobic liquid that does not change its aggregate is used as a blocking composition conditions under operating conditions, while the packer is placed at a level below the casing leakage interval, and the blocking composition is fed into the space above the packer between the casing and tubing at constant pressure, and flow is stopped when the supply pressure increases above the permissible value. 2. The method according to claim 1, characterized in that the low-freezing stabilized gas condensate, degassed low-viscosity oil with a viscosity of less than 100 mPa · s, used machine, transformer or turbine oil or mixtures thereof are used as a hydrophobic liquid, and as a hydrophobic liquid use solutions of water repellents in a hydrophobic liquid selected from the group: Neftenol ADB, heating oil, degassed, highly viscous oil with a viscosity of more than 100 mPa · s, oxidized oil.