RU2289010C1 - Method for drilling branching boreholes in horizontal well - Google Patents

Abstract

FIELD: oil and gas extractive industry, namely, methods for drilling branching boreholes in horizontal wells.

SUBSTANCE: method includes drilling in accordance to planned profile up to borehole branching point, performing necessary geophysical research, reinforcing the well and drilling branching boreholes. To provide for alignment-less precise insertion of drilling bit with bottomhole motor or tubing string into correct branching boreholes for performing required technological operations in well, drilling of first branching shaft is started with warping plane setting angle of deflector within limits of 70°-80° to the right or left from well borehole warping plane, depending on azimuth warping of second borehole. After completion of drilling of first borehole in accordance to planned profile and performing geophysical research, drilling of second borehole is started at same depth as first borehole, at setting angle of deflector warping plane within limits of 95°-100° relatively to warping plane of well borehole, while setting angle should be opposite to that during drilling of same interval in first borehole. If in first borehole setting angle is oriented to the left, then in second one it is oriented to the right, and vice versa. For boreholes to differ from each other, length of one of drilled boreholes is made greater for 10-20 meters. After completion of drilling of second borehole, geophysical research is performed analogically to case of first borehole. To provide for alignment-less insertion of pipes column being lowered into one of warping boreholes length of lower section, equal to 6-8 meters is made in form of arc with curvature radius equal to well warping radius at given section. When curved assembly being lowered into the well reaches cutting point, a mark is set at pipe thimble, which is applied onto rotor and pipe column is lowered further without rotation into one of branching boreholes, number of borehole is determined on basis of bottomhole dimensions. After performing necessary technological operations, if it is required to lower pipes column into another branching borehole, shoe of pipe column assembly is raised up to branching point and mark on thimble is shifted for 180° from original position by turning pipes column, and then the pipe is lowered into another borehole.

EFFECT: guaranteed alignment-less insertion of drilling tool or tubing string into correct branching borehole of horizontal well during various technological operations.

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Description

The invention relates to the oil and gas industry, and in particular to methods for drilling branched shafts in a horizontal well.

Known multi-hole horizontal drilling (see the book "Reference Engineer for Drilling", Volume 2. Edited by V.I. Mishchevich and N. A. Sidorov, M .: Nedra, 1973, pp. 184-185, Fig. a, b.), including drilling along the project profile to the branching point by using a deflecting arrangement, which allows evenly bending the trunks along circular arcs to angles of inclination of 90 ° or more and drilling in a shallow or horizontal formation, as well as obtaining predetermined radii of curvature in depending on the geometric shape of the layouts and the lower part of the drill string, carrying the required geophysical measurements, well casing and its development (see. the same source, p.190).

Also known is the "Method of opening productive formations of oil and gas wells" (see the description of the invention to patent RF No. 2213195, IPC 7 E 21 B 7/06, publ. BI No. 27, 09/27/2003) providing for the drilling of a horizontal wellbore along the project profile to the point of branching, conducting the necessary geophysical surveys, securing the well and drilling branched trunks in the reservoir.

The known method in technical essence is closer to the proposed one and can be adopted as a prototype.

A common drawback of both the analogue and the prototype is that if it is necessary to perform various technological operations, for example, lowering a bit with a downhole motor to further deepen the barrel or string of tubing, getting them into the desired branched trunks is very problematic, it takes an unreasonably long time , time costs at which sometimes up to 30 days or more. Hence the large monetary costs associated with the downtime of downhole equipment, work crew and late commissioning of the well.

The objective of the present invention is to provide a method for drilling branched shafts in a horizontal well, which ensures that the desired branched shafts in a horizontal well are oriented without drilling by a drilling tool or tubing string during various technological operations.

The problem is solved by the described method, including drilling along the design profile to the point of branching, conducting the necessary geophysical studies, securing the well and drilling branched trunks.

What is new is that, with the aim of an unoriented hit by a bit with a downhole motor or a string of tubing into the required branched shafts to perform the necessary technological operations in the well, the drilling of the first branching trunk begins with an angle of installation of the curvature plane of the deflector within 70-80 ° to the right or left the curvature plane of the wellbore, depending on the azimuthal curvature of the second wellbore, then after the completion of the drilling of the first well along the design profile and geo of scientific studies and for falling with the layout of the bottom of the drill string into the second barrel, the second hole is drilled at the same depth as the first shaft, at an angle of installation of the plane of curvature of the deflector within 95-100 ° relative to the plane of curvature of the wellbore, and the installation angle should be in the opposite direction than when drilling this interval in the first trunk, if the installation angle is to the left to the left, then to the second to the right, and vice versa, while to distinguish the trunks from each other, the length of one Urea trunks perform 10–20 m more; after drilling the second wellbore, geophysical surveys are also carried out, similar to those in the first wellbore, and to ensure that the descent pipe string is oriented in one of the branched trunks, the length of the lower section is 6–8 m , perform in the form of an arc with a radius of curvature equal to the radius of curvature of the well in this section, and when the curved layout is lowered into the well to the point of tapping on the pipe sleeve, a mark is set that is demolished on the the torus and then the pipe string is lowered without rotation into one of the branched trunks, and the number of the trunk is determined by the bottomhole size, after carrying out the necessary technological operations, if it is necessary to lower the pipe string into another branched barrel, the shoe of the pipe string assembly is raised to the branching point and the mark on the coupling set 180 ° from the original position by turning the pipe string, and then lower the pipe into this barrel.

The presented figures illustrate the essence of the invention, where FIGS. 1 and 2 schematically show the installation angle of the deflector curvature plane at an angle of 80 ° to the left of the wellbore curvature plane for drilling the first branched trunk, as well as the installation angle of the deflector curvature plane at an angle of 100 ° to the right of the curvature plane wellbore.

Figure 3 - elements of the design scheme of the layout elements of the bottom of the pipe string tubing or drill string.

Fig. 4 is a layout diagram of the layout of the bottom of the pipes in a branched trunk of a horizontal well. As can be seen from the drawing, for falling into one of the trunks, the lower end of the layout when lowering the pipes should move along the inner wall of the barrel from the center of curvature.

Drilling branched shafts in a horizontal well is as follows.

The horizontal wellbore is drilled according to the “Horizontal Wellbore Drilling Instructions”, see RD 39-0147-5 85-130-96, Almetyevsk, OAO Tatneft named after V.D.Shashina.

In accordance with this instruction, the well profile is selected based on the specific geological and technical conditions of drilling. The wellbore from the wellhead to the conventionally horizontal section is projected in one plane (according to the design azimuth), the azimuth of the conventionally horizontal section with an intensity of not more than 4 degrees / 10 m is allowed to change. The actual position of the wellbore in space is determined by systematic or constant inclinometric measurements in drilling process, including using downhole telesystems.

Designing the profile of a horizontal well starts from the bottom of the well, based on the geological and operational conditions, justifies the type of profile and the configuration of the horizontal section of the well, then, based on the technical capabilities, determine the design of the well and determine the geometric dimensions of the assemblies and their passage through the curved sections using the given deviation intensity.

After completion of the drilling of the wellbore and geophysical studies, the production casing with the entrance of 5-6 meters of the productive formation is lowered into the well and cemented using traditional technology. Then, after waiting for the cement to harden (OZC) and examining the quality of the cement stone in the annular space, an acoustic cement meter (ACC) is drilled with a stop ring, a cement beaker, the face is deepened according to the design profile, and then using the hydraulic trap or magnetic trap, the face is cleaned of metal chips. Then, branched trunks 1 and 2 are drilled (see Fig. 4, where branched trunks are shown) according to the stated objective of the invention - an unoriented hit by a bit with a downhole motor or tubing string into the desired branched trunks to perform various technological and technical operations in the well.

To do this, lower the bit with the downhole motor with the diverter and the telescope system down to the bottom and drill the first wellbore, with the angle of the deflector curvature plane set to 70-80 ° to the right or left of the well curvature plane (see Figs. 1 and 2) depending on azimuthal curvature of the second trunk. At the same time, drilling is carried out using a drilling fluid with increased endurance and not polluting the reservoir, for example, using a clay-free polymer drilling mud with a viscosity of 56-60 s. Further, the drilling of the barrel 1 is continued along the design profile to the design depth, i.e. lengths, after which geophysical studies are carried out in the drilled trunk.

Drilling of the second wellbore begins at the same depth as the first wellbore, at an angle of installation of the deflector curvature plane of 95-100 ° relative to the curvature plane of the wellbore at the depth of drilling of the first wellbore. The installation angle should be in the opposite direction than when drilling this interval in the first trunk. If in the first barrel the installation angle is to the left, then in the second - to the right (see figures 1 and 2), and vice versa. The length of one of the branched trunks is 10-20 m longer, to distinguish them from each other.

To ensure a disoriented entry of the descent pipe string into the desired branched shafts, the length of the lower section, equal to 6-8 m, is performed in the form of an arc with a radius of curvature equal to the radius of curvature of the well in this section.

Next, when the curved layout is lowered into the well to the point of tapping, a mark is placed on the pipe coupling, which is demolished on the rotor, and then the pipe string is lowered into one of the branched trunks without rotation. After performing the necessary technological operations, if it is necessary to lower the pipe string into another branched barrel, the shoe for the pipe string assembly is raised to the point of cutting (branching) and the mark on the coupling is set 180 ° from its original position by turning the pipe string, after which the pipe string is lowered before slaughter. The depth of the face as the pipes confirm the presence of pipes in the planned trunk.

As can be seen from figure 4, for getting into one of the branched shafts 1 of a horizontal well, the lower end of the layout 3 of the descent pipe string 4 should move along the inner wall of the barrel from the center of curvature (see figure 4).

This condition is satisfied then (see FIG. 3), when the length of the lower section of the assembly is equal to half L — the passable length of the string pipe being lowered into the well without deformation, and the angle of curvature between the sections should be determined from the magnitude of the curvature of the wellbore by 10 m. .3 the elements of the design diagram of the layout elements are shown. Below is a methodology for determining the L - passable length of the tubing string pipe without deformation. First, we determine the angle α - the angle between the radius of curvature of the well, perpendicular to the middle of L, and the radius of curvature of the outer wall of the barrel from the center of curvature, connecting one end of L, deg. (see figures 3 and 4):

where ⌀ tubing - diameter of the tubing string pipe, m;

Rвн is the radius of curvature of the wellbore from the center of curvature, m;

Rн is the radius of curvature of the outer wall of the barrel from the center of curvature, m;

R is the radius of curvature of the wellbore, m;

⌀skv - well diameter, m;

Δβ is the borehole curvature intensity per 10 m;

The authors of the proposed technical solution according to the above methodology determined the layout, consisting of 3 sections. The length of each section in this case is 2 m, the diameter of the tubing string is 73 mm, and the skew angle between the sections is 4 °.

The method was tested in commercial conditions when processing the bottom-hole zone of branched shafts in wells No. 1040 RG, 1041 RG, 11309 RG, 11321 RG, 11443 RG. The test results showed its high efficiency. In this case, the use of an expensive telesystem is eliminated, therefore, the time and money costs are reduced, the commissioning of wells is accelerated.

Claims (1)

A method of drilling branched shafts in a horizontal well, including drilling according to the design profile to the point of branching shafts, conducting the necessary geophysical surveys, securing the well and drilling branched shafts, characterized in that, in order to get the drill bit with a downhole motor or tubing string into the pipe the necessary branched trunks to perform the necessary technological operations in the well, the drilling of the first branch trunk begins with the installation angle the deflector curvature within 70-80 ° to the right or left of the wellbore curvature plane, depending on the azimuthal curvature of the second wellbore, after drilling the first wellbore along the design profile and conducting geophysical studies, the second wellbore begins to drill at the same depth as the first wellbore, at an angle of installation of the plane of curvature of the deflector within 95-100 ° relative to the plane of curvature of the wellbore, and the installation angle should be in the opposite direction than with a drill This interval in the first trunk, if the installation angle is to the left, then in the second - to the right, and vice versa, in order to distinguish the trunks from each other, the length of one of the drilled trunks is 10-20 m longer after the completion of drilling of the second trunk geophysical surveys are also carried out, similar to those in the first trunk, and to ensure an unoriented entry of the descent pipe string into one of the branched trunks, the length of the lower section, equal to 6-8 m, is performed in the form of an arc with a radius of curvature equal to the radius of curvature I bore the hole in this section, and upon reaching the curved layout lowered into the borehole to the point of kickoff, a mark is placed on the pipe coupling, which is demolished on the rotor, and then the pipe string is lowered without rotation into one of the branched shafts and the bore number is determined from the bottom hole value, after carrying out the necessary technological operations if it is necessary to lower the pipe string into another branched barrel, the shoe of the pipe string assembly is raised to the branching point and the mark on the coupling is set 180 ° from the original second position by rotating the pipe string is lowered further into the tube bore.

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