RU2317404C1 - Method to create gravel filter in horizontal bore - Google Patents

Abstract

FIELD: oil and gas industry, particularly construction of wells with horizontal and inclined bores having complicated configurations.

SUBSTANCE: method involves penetrating productive reservoir and installing casing pipe extending up to productive reservoir roof; delivering gravel composition to horizontal well bore by means of flow string; circulating liquid to wash-out gravel composition from flow string into horizontal well bore along with simultaneous flow string lifting; compacting gravel composition by periodic flow string lifting stopping along with gravel composition washing-out and flow string lifting so that flow string rests upon developed gravel filter.

EFFECT: possibility to create gravel filter during construction of well having inclined and horizontal bores having complicated configurations.

Description

The invention relates to the gas and oil industries and may find application in the construction of wells with horizontal and inclined shafts of complex configuration.

A known method of constructing the bottom of a production well, including opening a reservoir, lowering a perforated casing string, lowering a tubing string with a filter and installing it in the perforation interval of a casing string, creating a gravel filter at the bottom of the well by washing gravel into the annular space between the filter and casing and into the cavity behind the casing. With clay clays covering the reservoir, the latter is opened in its roof. A cavity for washing gravel is created mainly in the sole of the tire for the possibility of creating predominantly vertical loads from the gravel filter on the reservoir to maintain its integrity (RF Patent No. 2209944, CL ЕВВ 43/04, published on 08/10/2003).

The known method is applicable in wells with a horizontal wellbore with only a very small extent.

Closest to the invention in technical essence is a method of creating a downhole gravel filter, according to which, using drilling equipment, a productive formation is opened, a casing pipe is installed to the productive formation arch, a pipe with a filter is installed, and the gravel composition is delivered into the space below the productive formation arch. A cement string is installed inside the casing, a tubing with a filter is installed inside the casing. The filter is located in the zone of the reservoir below its arch. The gravel composition is a solution of water, cement and gravel, and the compaction of this gravel composition is carried out mechanically until it becomes a single perforated monolith. The particle size of the crushed stone used in the gravel composition is within 3-15 mm (RF Patent No. 2213207, CL ЕВВ 43/04, publ. September 27, 2003 - prototype).

The known method is applicable in wells with a horizontal wellbore with only a very small extent. The delivery of gravel to a long horizontal trunk is very difficult.

The proposed invention solves the problem of creating a gravel filter in the construction of wells with horizontal and inclined shafts of complex configuration.

The problem is solved in that in a method for creating a gravel filter in a horizontal well, including opening a producing formation, installing a casing pipe to the body of the productive formation, delivering the gravel composition to a space below the body of the productive formation, installing a tubing string and compaction of the gravel composition, according to the invention gravel composition is delivered to the horizontal wellbore in the tubing string, the gravel composition is washed out of the tubing string by circulation of the liquid pipes into the horizontal wellbore while lifting the tubing string while compaction of the gravel composition is done by periodically stopping the lifting of the tubing string when washing the gravel composition and lowering the tubing string all the way into the resulting gravel pack.

The features of the invention are:

1. opening of the reservoir;

2. installation of casing to the arch of the reservoir;

3. delivery of gravel to the space below the arch of the reservoir;

4. Installation of tubing string;

5. compaction of gravel composition;

6. delivery of gravel composition to the horizontal wellbore in the tubing string;

7. leaching by circulation of gravel composition from a tubing string into a horizontal wellbore;

8. the same with the simultaneous lifting of the tubing string;

9. compaction of the gravel composition by periodically stopping the lifting of the tubing string during leaching of the gravel composition and lowering the tubing string all the way into the resulting gravel pack.

Signs 1-5 are common with the prototype, signs 6-9 are the salient features of the invention.

SUMMARY OF THE INVENTION

When creating a gravel filter in wells with horizontal and inclined shafts of various configurations, i.e. having areas with a negative slope, rounding, wavy profile, etc., there are difficulties with the delivery of gravel to the remote and final sections of such wells. The proposed invention solves the problem of creating a gravel filter in the construction of wells with horizontal and inclined shafts of various configurations. The problem is solved as follows.

When creating a gravel filter in a horizontal well, the productive formation is opened and the casing is installed to the arch of the productive formation with cementing the annulus. Drilling a horizontal wellbore along the reservoir. The horizontal wellbore is not cased. The well is filled with a kill fluid. A tubing string with a temporary plug at the end is lowered into the well. The plug may be blind or perforated. When installing the column at the wellhead, each tubing is filled with gravel. The number of filled tubes is prescribed depending on the length of the horizontal section of the well. A string of gravel tubing is lowered into a horizontal section of the well. The temporary plug is removed, for example, by creating increased pressure in the tubing string with a blank plug, pumping a corrosive composition with a perforated plug, etc. Acid can be used as a corrosive composition, and non-ferrous non-ferrous metal such as magnesium can easily be destroyed in acid as a perforated plug material. The tubing string is raised to a small height of 1 to 10 m, and part of the gravel composition is washed out of the tubing string into the horizontal wellbore by circulating the liquid. The tubing string is lowered all the way into the resulting gravel filter, sealing it. The operations of raising and lowering the tubing string are repeated until the horizontal section of the well is completely filled with gravel and the gravel is washed out of the tubing string. As the fluid for circulation, a viscous thickened fluid or a high-density fluid easily washed out of the well by formation fluids or fluids from the surface, for example viscous oil, thickened water, highly saline water, and the like, is used. The viscosity and density of fluids are selected empirically, depending on the volume and fractional composition of the gravel filter and the length of the horizontal section of the well. The optimal viscosity can be considered as a fluid in the range of 50-150 centipoise and a water density in the range of 1.1-1.25 kg / m ³ .

Concrete example

Perform the device of a gravel filter in a horizontal oil well. The well is drilled to the reservoir at a depth of 1200 m, casing is installed to the arch of the reservoir with cementing the annulus. Then a horizontal wellbore is drilled along a 300 m long productive formation. The horizontal wellbore has a complex configuration due to the spiral shape in plan. The horizontal wellbore is not cased. The well is filled with a kill fluid. A tubing string with a temporary blank plug at the end is lowered into the well. When installing the column at the wellhead, each tubing is filled with a gravel composition consisting of gravel with a fraction of 3 to 15 mm and filled with water with a density of 1.24 kg / m ³ obtained by dissolving calcium chloride in water. The number of filled tubes is prescribed depending on the length of the horizontal section of the well. Based on the fact that the borehole diameter is larger than the diameter of the tubing string total, the length of the filled pipes is set equal to 600 m. The tubing string with gravel composition and high density water is lowered into the horizontal section of the borehole. The temporary plug is removed by creating increased pressure in the tubing string. Raise the tubing string to a height of 5 m and circulate a fluid density of 1.24 kg / m ^{3 and} wash part of the gravel from the tubing string into the horizontal wellbore. The tubing string is lowered all the way into the resulting gravel filter, sealing it. The operations of raising and lowering the tubing string are repeated until the horizontal section of the well is completely filled with gravel and the gravel is washed out of the tubing string. The tubing string is raised from the well. A tubing string with a pump is lowered into the well and put into operation. The result is a well with a horizontal section of complex configuration, filled with a gravel filter.

The application of the proposed invention will create a gravel filter in the construction of wells with horizontal and inclined shafts of complex configuration.

Claims (1)

A method of creating a gravel filter in a horizontal well, including opening a producing formation, installing a casing pipe to the arch of the producing formation, delivering the gravel composition to a space below the arch of the producing formation, installing a tubing string and compaction of the gravel composition, characterized in that the gravel composition is delivered to the horizontal wellbore in the tubing string, the gravel composition is washed out of the tubing string in a horizontal fluid circulation borehole while lifting the column tubing and seal the gravel composition produced by intermittently stopping the lifting column tubing when leaching gravel composition and lowering the string of tubing to the stop formed in the gravel pack.