RU2421608C1 - Procedure for replacement of oil from horizontal well - Google Patents

Abstract

FIELD: oil and gas production. ^ SUBSTANCE: perforated flow string is lowered into drilled borehole. Annular space is isolated up to a horizontal borehole. Oil-well tubing is installed into the flow string. Annular space is sealed with an insulation unit. Replacing agent is supplied into an end portion of the flow string behind the insulation unit; production is withdrawn at the beginning of a horizontal section of the flow string. According to the invention before the flow string is lowered into the borehole up to the horizontal section there is lowered a casing string which is successively cemented. Before lowering the flow string is outside equipped with an inflatable packer between the beginning of the horizontal section and the end section. The packer is communicated inside with the flow string by means of overflow orifices on the side of a wellhead from the insulation unit. Working substance is pumped via inter-tubular space via a process valve with its outlet of the end portion communicated with the flow string. Production is withdrawn via the production string communicated with annular space of the flow string by means of radial channels. ^ EFFECT: raised efficiency of reservoir heating facilitating flow of heated production via production string; simplified repair of well due to possibility to extract casing string in case of necessity. ^ 1 dwg

Description

The invention relates to the field of oil production using heat, mainly from reservoirs with heavy, highly viscous or bitumen oil in combination with the drilling of horizontal wells.

The well-known "Method of enhancing oil recovery" (US patent N 4982786, EV 3/11, publ. 08.01.1991), which consists in the fact that at least two horizontal bores are drilled from one well, perforated casing strings are installed, the upper the horizontal bore is perforated along the lower generatrix, and the lower one is perforated along the upper one, the annulus is cemented above the horizontal boreholes, the tubing is installed in the casing to the lower horizontal bore, the centers are centered in them using the packers, on Ba tubing pumped coolant, and the product is transported from an upper shell side of the barrel through the annular channel.

The well-known "Method of improving oil recovery in the development of formations" (US patent N 4961467, ЕВВ 43/24, publ. 09.10.1990), saturated with viscous, heavy oil, which consists in injecting steam into the formation through an injection well into the oil-water zone and oil displacement through producing wells. At the same time, at the beginning of the cycle, production wells are closed until the pressure in the formation reaches a value close to the pressure of the fracturing. After that, the injection well is closed, and through the production begins the selection of the product.

Common disadvantages of the methods are:

- firstly, high energy intensity, due to the need to heat a significant amount of the reservoir between the upper and lower horizontal shafts and the associated unproductive heat loss;

- secondly, insufficiently high operational reliability, due to the fact that insufficiently warmed up product is displaced into the upper horizontal trunk, and when transporting it through the annulus, heat is removed from the coolant, which requires its elevated temperature.

The closest in technical essence is the "Method of thermal displacement of oil from a horizontal well" (patent RU No. 2067168, ЕВВ 43/24, publ. 09/27/1996), which consists in the fact that a perforated casing is installed in a drilled well, the annulus is cemented to horizontal bore, tubing is installed in the casing, they are centered in the casing with the help of a packer, coolant is supplied through the tubing, and the product is transported through the annular annulus TSS, wherein the casing perforation is carried out by forming in the annular end portion of the packer and the beginning of the horizontal section immediately behind the cemented annulus, the coolant is fed to the end portion of the casing of the packer, and the product is withdrawn via the perforation of the casing at the beginning of the horizontal section.

The disadvantages of this method are:

- firstly, the low efficiency of the formation heating, since when the coolant (hot gas) is injected, only the near-barrel part of the horizontal section is heated, since the bulk of the hot gas is concentrated in the horizontal section;

- secondly, it is impossible to pick up pumping equipment for lifting the heated product along the annular annular space, in addition, the low lifting speed along the annular annular space leads to cooling of the heated product;

- thirdly, well repair is complicated, since according to the design of the well, the casing is non-recoverable, which leads to additional financial and material costs when repairing the well.

The objective of the invention is to increase the efficiency of heating the formation with the possibility of lifting the heated product along the tubing string (tubing), as well as simplifying well repair due to the possibility of removing the casing if necessary.

The problem is solved by the method of displacing oil from a horizontal well, including installing a perforated production string in a drilled well, isolating the annulus to the horizontal well, installing tubing in the production string, sealing the annulus with an isolation unit, pumping the displacing agent into the end of the production string for isolation unit and product selection at the beginning of the horizontal section of the production casing.

New is that before the production string is lowered into the well to the horizontal section, a casing is installed with its subsequent cementing, and between the beginning of the horizontal section and the end part from the outside the production string is equipped with an inflatable packer, which is communicated from the inside bypass holes located on the mouth side the isolation unit, with the production casing, and the working agent is injected through the annulus through the process valve enny yield with an end portion of the production string and the product collected on a column of tubing communicated with the production casing annulus radial channels.

The drawing shows a diagram of an implementation of the proposed method for displacing oil from a horizontal well.

A method of displacing oil from a horizontal well is that a casing 3 is installed in a drilled well 1 to a horizontal section 2, followed by its cementing.

Before the perforated openings 4 of the production casing 5 are lowered into the casing 3 of the well 1 between the beginning of the horizontal section 2 and its end part from the outside, the production casing 4 is equipped with an inflatable packer 6.

Next, the production casing 5 is installed in the well 1, after which the annulus 7 is isolated to the horizontal section 2 with the packer 8.

A tubing string (tubing) 9 is installed in the production casing 5, 9 is sealed in a horizontal section 2 of the well 1 annulus 10 by the isolation unit 11.

The inflatable packer 6 is internally communicated by bypass holes 12 located on the side of the mouth (not shown) from the isolation unit 11 with production casing 5.

The coolant (for example, hot gas) is pumped through the annular space 10 through the holes 13 in the tubing string 9 and the process valve 14, in communication with the output from the end of the production string 5, and then hot steam enters the formation through its perforated holes 4, warming it diametrically outward from the horizontal section 2. The annulus 7 and the packer 8 exclude direct contact of the production string 9 with the inner walls of the well 1, which eliminates premature cooling of hot steam .

The preheated product is taken at the beginning of the horizontal section 3 of the well 1, while the preheated product enters the annulus 15 of the production string 5 and through the radial channels 16 enters the tubing string 9, where it is received by the pump 17, which can be of any known design, for example screw. Pump 17 pumps the heated product along the tubing string to the surface.

Alternatively, when implementing the method, it is possible to lower a part of the tubing string 9 located in the horizontal section 2 together with the production string 5, after which the upper part of the tubing string 9 is lowered into the production string 5, which is tightly fixed to the bottom of the tubing string by means of the coupling 18 9.

If necessary, production casing 5 and tubing string 9 can be removed and repairs performed in well 1.

The proposed method of displacing oil from a horizontal well allows to increase the efficiency of heating the formation, that is, to expand the coverage of the heated zone of the formation due to the fact that the coolant flows directly into the formation, and not into the horizontal section of the well. The rise of the heated product is carried out using a pump along the tubing string, which, when warmed up, raises it to the day surface. In addition, the ability to extract production casing during well repair facilitates and accelerates the repair process, thereby avoiding additional financial costs.

Claims (1)

A method of displacing oil from a horizontal well, including installing a perforated production string in a drilled well, isolating the annulus to the horizontal well, installing tubing in the production string, sealing the annulus with an isolation unit, injecting the displacing agent into the end of the production string for the isolation unit, and product selection at the beginning of the horizontal section of the production casing, characterized in that before the launch casing string is installed in the well up to the horizontal section with its subsequent cementing, and between the beginning of the horizontal section and the end part from the outside, the production string is equipped with an inflatable packer prior to launching, which is internally communicated with bypass holes located on the mouth side of the isolation unit with the production string, moreover, the injection of the working agent is carried out through the annular space through a process valve in communication with the output from the end columns, and the product is taken along the tubing string connected to the annular space of the production string by radial channels.

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