RU2283417C1 - Method for multibranch well erection - Google Patents

Abstract

FIELD: well drilling technology, particularly directional drilling.

SUBSTANCE: method involves constructing upper part of main well bore up to productive horizon; casing the bore with casing pipes; deepening lower part of main bore up to the first side branch level; drilling side branch; determining density of fluid present in the branch; filling the drilled side branch with substance, which hardens in liquid and has density equal to that of the fluid; performing time delay for above substance hardening before further drilling; deepening lower part of main bore up to next side branch level; drilling next side branch and performing similar branch isolation operations. The hardening substance prevents side bores from drilling mud ingress and eliminates drilling mud absorption with reservoir. Number of side branches and their location may change in dependence of reservoir or interlayer location and parameters. After all side branch construction main bore is deepened up to predetermined depth and is maintained in opened state. Before well bringing in operation the hardening substance is washed out from side branches, for instance with the use of purified liquid or fresh water.

EFFECT: reduced costs of branch filling with hardening substance and hardening substance removal from bores, prevention of drilling mud penetration in productive reservoirs and, as a result, possibility to retain collecting properties of productive reservoirs and well output.

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Description

The invention relates to a technology for drilling wells, and in particular to methods for constructing a multilateral well.

A known method of conducting and fixing a multilateral well (Patent RU No. 2074944, IPC 7 E 21 B 7/04, publ. BI No. 7 of 03/10/1997), including drilling the main and additional shafts and attaching additional shafts with shanks from the main trunk, while drilling the main trunk is carried out to the last branching depth, after which the main shaft is fastened with pipes, then additional trunks are drilled with their subsequent fastening.

The disadvantages of this method are:

- firstly, an increase in the time for fixing the sidetracks by casing pipes;

- secondly, increased metal consumption of the well structure.

The closest is the method of construction of a multilateral well (Patent RU No. 2205935, IPC 7 E 21 B 7/06, 43/10, publ. BI No. 16 of 06/10/2003) in unstable rocks, including sequential top-down drilling of the main and side trunks, fixing the main trunk with casing pipes, fixing the side trunks, while the main trunk is fixed with casing strings to the productive horizon, and after drilling each side trunk, it is fastened with permeable material, such as sand, gravel, the permeability of which is higher than that of p genus producing formation, and after the construction of the lateral bore is drilled core hole to a fixed depth and produce its fastening by means of perforated casing or filter, followed by filling the annular space between the filter and the wellbore wall permeable material having a particle size greater than the width of the filter slots.

The disadvantages of this method are:

- firstly, it does not sufficiently reliably isolate the reservoir, since the permeable material (sand, gravel, etc.) located in the sidetracks during drilling, gets wet and passes through itself the fluid used in the drilling process, as a result of which the latter gets into the reservoir layer and absorbed by it;

- secondly, the high costs of permeable materials when filling the annular space between the filter and the wall of the well cause unjustified material and financial costs;

- thirdly, a very laborious process of removing permeable material from the sidetracks after drilling.

An object of the invention is to increase the protection of productive formations from getting into and absorbing the fluid used in the process of drilling the well, as well as reducing the cost of filling the sidetracks with permeable material and then removing it before putting the well into operation.

The technical problem is solved by the proposed method for constructing a multilateral well, including drilling to the productive horizon and securing the main trunk with casing pipes, sequential top-down drilling of the main and side shafts, and after each side well is drilled, they are filled.

What is new is that before filling each side barrel, the density of the liquid in this barrel is examined, after which the filling is carried out hermetically only at the entrance to the side barrel in the form of a substance that solidifies in a liquid medium of the same density as the density of the liquid in this side barrel , before further drilling, an exposure is given sufficient to cure the substance and then wash it out of the sidetracks after drilling.

The drawing shows a multilateral well, the lateral trunks of which are fixed by the proposed method.

A method of constructing a multilateral well is as follows.

The upper part 1 of the main trunk is built up to the productive horizon and secured by the casing 2, the lower part 3 of the main trunk is deepened to the depth of the location of the first side trunk 4. The side trunk 4 is drilled, then the density of the fluid in this trunk is examined. As a result, the drilled lateral barrel 4 at the inlet is hermetically filled with a substance 5 that hardens in a liquid medium (for example, organosilicon product 119-296T, produced in accordance with TU 6-00-05763441-45-92. Reference Guide for the isolation of water inflows in wells, p. 18 , Table 7, Almetyevsk, 1999, 70 pp.) of the same density as the density of the fluid in the lateral barrel 4. Before further drilling, an exposure is given sufficient to cure the substance.

Then, the lower part 3 of the main trunk goes deeper to the location of the next side trunk 6, after drilling of which the similar operations for isolating the side trunk 6 described above are carried out.

The substance 5 hardening in a liquid medium reliably isolates the penetration of drilling fluid into the side shafts 4, 6, and also prevents its subsequent absorption by the formation.

The number of sidetracks and their location may vary depending on the nature and location of the formation or interlayers.

After the construction of all side shafts, the lower part 3 of the main trunk deepens to a set depth that remains open.

Before putting the well into operation, the substance 5 hardening in a liquid medium is washed out, for example, with refined liquid or fresh water (not shown in the drawing).

Thanks to the use of a substance 5 that hardens in a liquid medium and is hermetically installed only at the entrances to the sidetracks, the costs of filling and removal of a substance that hardens in a liquid medium are reduced; moreover, productive formations are reliably protected from penetration into them and their absorption of the liquid used during drilling wells, which preserves the reservoir properties of the reservoir and production capabilities of the well.

Claims (1)

A method of constructing a multilateral well, including drilling to a productive horizon and securing the main trunk with casing pipes, sequential top-down drilling of the main and side shafts, and after drilling each side well, filling is performed, characterized in that before filling each side well, the density of the liquid located in this barrel, after which the filling is carried out hermetically only at the entrance to the lateral barrel in the form of a substance hardening in a liquid medium The same density as the density of the fluid in a given sidetrack, before further drilling is given a shutter speed sufficient to cure the material and then washed out of the sidetracks after drilling.