RU2531416C1 - Downhole oil-field equipment operating method - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention is related to oil industry and may be used during operation of downhole oil-field equipment comprising swellable packers. The downhole oil-field equipment operating method includes installation of a swellable packer to the equipment, application of temporary coating to the swellable packer, running in of the equipment to the well, removal of the temporary coating, swelling of the packer and operation of the equipment with the swelled packer. The friction-reducing coating is used as a temporary coating. The well is filled preliminary with liquid in which the swellable packer swells. Upon installation of the equipment in the well the borehole liquid is replaced by the liquid in which the packer swells and the temporary coating is removed simultaneously.

EFFECT: increase in production.

Description

The invention relates to the oil industry and may find application in the operation of downhole oilfield equipment containing swellable packers.

A known method of anchoring and isolating at least one zone in the wellbore, comprising the following steps: (a) installing a unitary downhole tool containing a mandrel having an upper end, lower end, outer wall surface, a longitudinal channel passing through it and having an axial line, a plurality of anchor fasteners located at a distance from each other around the circumference and longitudinally along the outer surface of the mandrel wall, each of the plurality of anchor fasteners contains at least two telescopic their element having an anchor channel located in at least one of the at least two telescopic elements and hydraulically connected with the longitudinal channel, and an insulating element located on the outer surface of the mandrel wall and around each of the many anchor fasteners to facilitate isolating with an insulating element at least one zone in the wellbore; (b) lowering the unitary downhole tool to the desired location in the wellbore; (c) extending each of the plurality of anchor fasteners until a sufficient amount of the plurality of anchor fasteners contacts the surface of the wall of the wellbore; and (d) contacting the insulating element with the surface of the wall of the wellbore. Step (c) may be performed before step (d). Step (g) may be performed before step (c). Step (c) can be performed simultaneously with step (d). Step (g) can be performed by punching the insulating element with at least one of the anchor fasteners to ensure that the well fluid is in contact with the swelling material contained in the insulating element (RF Patent No. 2491409, class E21B 23/04, publ. 27.08. 2013).

Closest to the proposed invention in technical essence is a method of controlling the swelling of an elastomer for use in the bottom of the well, comprising placing the downhole tool in the wellbore, the downhole tool containing a swelling core and a coating enclosing a swellable core in the shell, the coating being made of material, containing a component soluble in the selected fluid and a component insoluble in the selected fluid; and effecting the swelling device with the selected fluid to increase the permeability of the coating to provide swelling of the swelling core. The downhole tool is a packer. The component soluble in the selected fluid is oil soluble, and the selected fluid is the fluid of the wellbore containing hydrocarbons. A component soluble in the selected fluid is one or more selected from the group consisting of polystyrene, polyalphamethyl styrene, low molecular weight polyolefins, copolymers of styrene and acrylonitrile, polymethyl methacrylate and polycarbonate. The component soluble in the selected fluid is water soluble, and the selected fluid is a water-based fluid. The water soluble component is composed of polyvinyl alcohol, an organic salt, an inorganic salt, or a combination thereof. The swellable core contains a polymer that swells under the influence of the selected fluid. The downhole tool further comprises a layer that eliminates the bonding between the swellable core and the coating. A method of manufacturing a downhole tool, comprising: preparing a swellable core containing a swellable polymer; and enclosing a swellable core in the coating shell, the coating being made of a material containing a component soluble in the selected fluid and a component insoluble in the selected fluid. The swellable polymer swells under the influence of the selected fluid. The coating is not tightly connected with the swelling core (Application for invention of the Russian Federation No. 201007097, class E21B 33/00, publ. 08.27.2011 - prototype).

A disadvantage of the known technical solutions is the possibility of swelling packers during descent into the well, especially during technological or unexpected stops.

The proposed invention solves the problem of increasing the reliability of the installation of downhole oilfield equipment containing swellable packers.

The problem is solved in that in the method of operating downhole oilfield equipment, including installing a swellable packer on the equipment, applying a temporary coating to the swellable packer, lowering the equipment into the well, removing the temporary coating, swelling the packer and operating the equipment with the swollen packer according to the invention as a temporary coating use a coating that reduces friction, pre-fill the well with a liquid in which the swellable packer does not swell, and after installing the equipment in Vazhiny replace the wellbore fluid in the fluid in which the swellable packer swells with simultaneous removal of the temporary coating.

SUMMARY OF THE INVENTION

When oilfield equipment containing swellable packers with a temporary protective coating is lowered into the well, there is a risk of damage to the coating, contacting the swellable packer with the borehole fluid in which it swells, and setting the packer in the well in an interval far from technologically necessary. This danger especially manifests itself during technological or unforeseen stops during descent. Existing methods solve this problem only partially by coating the packers. The proposed invention solves the problem of increasing the reliability of the installation of downhole oilfield equipment containing swellable packers. The problem is solved as follows.

During the operation of downhole oilfield equipment, a swellable packer or several packers are installed on the equipment, a temporary coating is applied to the swellable packer, the equipment is lowered into the well, temporary coating is removed, the packer swells and equipment is operated with a swollen packer. As a temporary coating use a coating that reduces friction. The material for such a coating may be a surfactant or a mixture of surfactants, soap or a mixture of soaps, and the like. It is preferable to use a coating material under normal conditions and in the conditions of downhole conditions in the solid state. The material is melted before application and applied to the packer or dissolved, applied to the packer and dried to form a coating. In this condition, equipment with a packer or group of packers thus prepared is lowered into the well. Before launching, the well is pre-filled with liquid in which the swellable packer does not swell. So, if the packer swells in water, then the well is filled with oil, and if the packer swells in oil, then the well is filled with water. After the descent and installation of equipment in the well, the well fluid is replaced with a fluid in which the swellable packer swells, while the temporary coating is removed. Removal can be carried out by pumping liquid, technological exposure to dissolve the coating material, etc. As a result, it is possible to deliver the downhole equipment at a predetermined interval without fear of premature packer swelling.

Case Studies

Example 1. Isolate water inflow in the horizontal well of an oil well. Water inflow interval 1340 ÷ 1370 m (along the trunk). An assembly is made up of an unperforated pipe and two external water-swellable packers. Packers are coated with molten laundry soap. The well is filled with oil. After determining the interval of water inflow, the assembly is lowered to the well. During the descent, no packers swell. Soap prevents water from entering the water-swellable elements of the packers, and also reduces friction against the walls of the well and facilitates the passage of the assembly into the well. The arrangement is installed in the well so that the interval of water inflow remains between the water swellable packers. Replace oil in the well with water. By circulating water, soap is removed from the surface of the packers and left to swell. After the packers swell, the tightness of the lower and upper packers is checked by geophysical research on the tributary. They exploit a well, select reservoir products with reduced water cut.

Example 2. Perform as example 1. As a temporary coating material of the packers using the surfactant OP-7, diluted in water to a creamy state, which is coated with water-swellable packers. After replacing the oil in the well with water, technological exposure is carried out until the temporary coating dissolves.

The application of the proposed method will solve the problem of improving the reliability of the installation of downhole oilfield equipment containing swellable packers.

Claims (1)

A method of operating downhole oilfield equipment, including installing a swellable packer on equipment, applying a temporary coating to the swellable packer, lowering the equipment into the well, removing the temporary coating, swelling the packer and operating the equipment with a swollen packer, characterized in that a coating that reduces friction, the well is pre-filled with a liquid in which the swellable packer does not swell, and after installing the equipment in the well, the well is replaced liquid to the liquid in which the swellable packer swells with simultaneous removal of the temporary coating.