RU2224873C2 - Well construction finishing method - Google Patents

Abstract

FIELD: oil and gas extraction industry. SUBSTANCE: method includes lowering of impermeable cover in form of enrolled metallic sheet into previously bored portion of productive layer along the pipes column. Said sheet is then mounted in a way to tightly adjoin well walls by well perimeter. Before the mounting procedure disk-shaped springs made of spring steel are regularly placed and fixed on the sheet starting from edges to unroll the sheet later. The sheet is 1-2 mm thick and is made from grade 3 steel. EFFECT: simplification of protection means for productive layers. 2 cl, 6 dwg

Description

The invention relates to the oil and gas industry, in particular to methods for completing well construction, and in particular, to protecting productive formations from contamination during well attachment.

A known method of completing construction of a well [1], including drilling a well to a design depth, injecting a solution of chemically active components into the interval of the reservoir, neutral to the filtration properties of the reservoir, perforating the latter with explosive perforators and securing the well. In this case, a solution that is neutral to the filtration properties of the reservoir, filling the pores and channels of the reservoir, protects it from the contaminating action of the cement filtrates and the products of its hydration.

The known method finds limited application. For example, it is not applicable in the construction of wells of a multilayer oil field. This is explained by the fact that when drilling a well in case it is used in the first oil reservoir, discovered by drilling, the injected neutral solution, followed by continued drilling under the influence of alternating pressure in the well, the solution that protects the formation from pollution goes back from the channels and pores of the formation and therefore ceases to fulfill its protective properties. In addition, the method is not technologically advanced. It requires calling a geophysical batch for a backache, strict adherence to the weight ratios of the components of the composition, preparation, and delivery to the well.

There is also known a method of completing well construction [2], which involves opening a productive formation by drilling using a non-polluting wash fluid, such as a hydrocarbon-based solution, blocking it with an impermeable shell and securing the well by lowering the production casing into the well followed by cementing it.

This method is applicable in the construction of a multi-layer oil field in order to protect against pollution of productive formations.

However, the use of this method causes a number of difficulties associated with the secondary opening of the reservoir while creating a hydrodynamic connection between the reservoir and the well, as well as with the installation of an impenetrable shell in the interval of the reservoir.

This is explained by the fact that the installation of a steel metal shell 5-8 mm thick opposite to the productive formation plus a production casing thickness of 8-10 mm and a cement ring between them after fixing the well lead to a decrease in the efficiency and quality of opening using conventional perforators. Therefore, in connection with this there is a need to develop and produce more powerful cumulative rotary hammers, the use of which would lead to a violation of the integrity of the cement stone behind the production casing and, as a consequence, to premature flooding of the formation. In addition, the installation of a steel shell of large thickness, which is provided for by the method, opposite the reservoir, requires sophisticated equipment that ensures its tight fit to the walls of the well, not including the complexity of manufacturing the shutter itself, is associated with an unreasonably large expenditure of time and labor.

A device for the selective isolation of sections of a wellbore [3] is known, where a method for completion of a well is described, which includes running a pipe string into a pre-expanded interval of a productive layer of an impenetrable shell in the form of a rolled sheet metal sheet and installing it with a tight fit to the walls of the well throughout perimeter. The specified method by technological essence is closer to the proposed one and it can be adopted as a prototype.

Its disadvantages include the following.

1. Since a metal sheet to be rolled up is designed for unwinding due to its elastic deformation, therefore, the metal sheet is selected entirely from spring steel. This circumstance creates big problems in the implementation of the formation of the roll by folding (see the attached calculation of the force of pressing the strips (shells) of a metal sheet (patch) to the wall of the well). This is especially true when the overlapping interval of the reservoir is more than 3-4 meters.

2. In addition, the wellbore that has left drilling is not strictly cylindrical, therefore, a reliable and tight fit of the metal sheet (patch) to the walls of the well is not ensured and, in turn, the set goal of protecting the insulated formation from pollution is not achieved.

3. A device for delivery and its installation in an isolated interval is metal-consuming, for example, if there is a need for its installation in the interval of a wellbore of 8-10 meters.

Therefore, these shortcomings did not give the possibility of wide industrial application.

The objective of the present invention is to provide a method for protecting productive formations from pollution by simpler technical means, with less time, metal, and also reducing the complexity of installing a metal shell.

The problem is solved by the described method, including the descent on the pipe string into a pre-expanded interval of an impermeable sheath in the form of a rolled sheet metal sheet and its installation with the possibility of tight fit to the walls of the well along the entire perimeter.

New is that on a metal sheet with a thickness of 1-2 mm made of steel of grade 3, pre-fixed leaf springs made of spring steel at equal distances from each other, starting from the extreme sections of the metal sheet, for its unwinding.

Also new is the fact that leaf springs are made of spring steel, for example, 60C2 steel or 65G steel.

An analysis of selected well-known technical solutions found during patent research showed that at the filing date of the application, objects characterized by such a combination of essential features and which, if used, would not have achieved a higher technical result, as proposed, are not found, which allows a conclusion on the conformity of the claimed object with the criteria of “Novelty” and “Inventive step”.

And its industrial applicability is confirmed by a full description of its implementation.

The presented figures illustrate the essence of the invention, in which Fig. 1 shows a well with a section in contrast to the reservoir of complications of impenetrable shells, and also opposite to a productive formation in a one-layer oil field after attaching the well.

Figure 2 - scan of a rolled sheet of metal sheet, visible leaf springs attached to it.

Figure 3 - impermeable shell in the form of a metal sheet rolled up into a roll and fixed from opening by clamps, general view.

Figure 4 - sequentially installed impermeable shells in the extended interval of the reservoir of high power after drilling a cement bridge, in section.

Figure 5 schematically shows with overlapping each other installed impermeable shells in the interval of a productive formation of high power, when the formed cement bridge is drilled, in section.

In Fig.6 - a reservoir with the same capacity as in Figs.4 and 5, opposite which impenetrable shells are overlapped and cemented, after drilling a cement bridge inside the well, in a section.

The method is carried out in the following sequence.

According to the well construction project, intervals for washing liquid absorption or other complications are determined, the thickness of the productive formations being opened and preparatory operations for the manufacture of impermeable shells 1 (see Fig. 2) from sheet iron 1-2 mm thick from steel, for example, are carried out , grades 3. Starting from the extreme sections, at equal distances from each other to the sheet iron, fix leaf springs 2 (see figure 2) made of spring steel, for example, grade 60C2 or 65G for the implementation of its unwinding tions.

Then they are rolled up (see FIG. 3) with an outer diameter smaller than the diameter of the borehole 3 and fixed in this position with clamps 4. The width of the sheet iron is taken into account so that when the roll is untwisted, it is snug against the walls an extended wellbore could overlap its entire perimeter.

Before installing an impermeable shell in the well, the interval of the productive formation 5 is expanded using traditional extenders with sliding cones, for example, developed by the TatNIPIneft Institute, after which it is desirable to carry out deep cleaning of the formation, for example, by implosion treatment in order to restore its reservoir properties.

Then, on the string of drill pipes or tubing, the impermeable sheath 1 is lowered using a device that allows it to be released from the fixing clamps 4, and using centralizers in the installation interval. After release from the fixing clamps, an impermeable shell under the action of elastic deformation of the leaf springs 2 is untwisted and tightly adheres to the walls of the well along its entire perimeter (see figure 1).

Depending on the thickness of the reservoir, an impermeable sheath is installed sequentially or sequentially with an overlap (see FIGS. 4, 5 and 6).

When drilling a well, drilling fluid-absorbing formations 6 may be opened. In such cases, the interval of formations covered by impermeable shells is cemented, followed by drilling of the formed cement bridge. Next, the production casing is lowered into the well and cementing is carried out using traditional technology and equipment. This completes the completion of the well.

The technical and economic advantage of the proposal is as follows. When using the method, metal savings are achieved by a factor of 2–3, time costs are reduced by a factor of 3–4 or more. The method does not require sophisticated equipment for its implementation, technological.

Sources of information

1. RF patent No. 2061837, cl. E 21 B 33/13, publ. In BI No. 16, 1996, "Method of completion of the well."

2. A.S. №911015, M _cl E 21 B 33/13, 1980 G. "well completion process."

3. A.S. No. 5778433, M _class E 21 B 33/13, 1977. "Method of completion of the well" (prototype).

Claims (2)

1. The method of well completion, including the descent on the pipe string into a pre-expanded interval of the productive formation of an impenetrable shell in the form of a rolled sheet metal sheet and its installation with the possibility of tight fit to the walls of the well along the entire perimeter, characterized in that on a metal sheet 1- thick 2 mm, made of grade 3 steel, pre-fixed leaf springs, of spring steel, at equal distances from each other, starting from the extreme sections of the metal sheet, for the direction of its unwinding. 2. The method of completion according to claim 1, characterized in that the leaf springs are made of spring steel, for example, 60C2 steel or 65G steel.

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