RU1798483C - Method for cementing flow string in well - Google Patents

Abstract

Using; in oil industry when cementing an operating pipe string in oil and l: -7 :; : ;:: -:I AM. V ....:; gas wells in the intervals; productive formations with: suspended water or in the presence of closely spaced water: porous productive formations. SUMMARY OF THE INVENTION: The bottom of the column is equipped with a packer self-sealing device with increasing pressure below it. Inside the column above the main stop-ring of the mouth, a; on av.4.i; c; t: 7 dol Llit l b; nre; / srz-but e-stop ring; After the column is lowered into the well, the poker device is installed below the oil reservoir (above suspended water in a monolithic reservoir or; an aquifer-HbiM reservoir with botanically). Into the column Za; Kamiva1o1 Cement mortar; isolate the reservoir layer rtprudktivnbgo self-compensating for the pressure by the packer for the pressure f $ s $ given when cutting the stb-cbld, create pressure on the water reservoir while setting: solution. 2 ill.

Description

: The invention relates to the oil-producing industry and can be used when cementing production columns in oil and gas fields in any way, in the inter- ests of products for the production of oil-bearing niacrpB; (strata with pddo {evenby vredey or in the presence of close-ups. many water-pressure strata below the oil-bearing), as well as during cementing of conductors and intermediate columns.

d The invention is designed to improve the cementing quality of production casing due to its more reliable

sealing the cement ring in the intervals of water inflow under the oil reservoir.

A diagram of the implementation of the method is presented, t and: 2, where A is a self-tight - cache-ting device (unit); 1 - upper shear stop krltsb; 2 - lower (open) stp-ring (or standard cementing check valve type ti | CG, Ei); 3i-standard filling plug; 4 dd ke ruyu elements-cuff; 5 - cpesfibieiurtHnbKH upper Stop: (olts; 6 - production string: 7 - casing sleeve.

Xj

Yu

00

and

00

SL

The method is carried out as follows.

The column below the reservoir (but above the flooded layers or interlayers) is equipped with a self-sealing packing unit, an additional shear (upper) stop ring is installed below the packing device (clamp it between the casing 6 in the sleeve connection). The installation location of the stop ring 1, and, consequently, the volume of solution in the pipes between the upper and lower stop ring

2 (Vi) calculate, based on the required volume of cement slurry crushed into the under-packer space behind the column. Next, the cement slurry is prepared and injected in the volume V Vi + V2 + Va where Vi is the volume of the crushed mortar;

V2 is the volume of the solution below the TsKOD check valve, which simultaneously serves as the lower stop ring (cement cup);

Vs is the volume of the mortar to fill the annular space, ensuring the design cementation height.

Then grouting the grouting mortar

3 before reaching the stop ring 1 (Fig. 1); the pipe 7 fixed in the sleeve. At excessive (additional) pressure (e.g. 3.0 MPa), the safety pins of the packer assembly (not shown in Fig. 1) are cut off and the packer elements - cuffs 4 are opened against the borehole wall. A further increase in pressure (for example, to 5.0-6.0 MPa) leads to a cut off of the studs 5 and the solution in the volume Vi is pressed into the pores. And the cracks of the flooded (water-pressure) formations behind column b until the stop pressure is reached and the plug reaches the main stop rings 2 (TsKOD), (Fig. 2). The cement slurry remaining in the under-packer space is compacted. It is not ruled out that some of the cement slurry is left from the volume Vi above the stop ring 2 due to an excessive increase in pressure. Therefore, it is recommended to have an additional sump in the well in volume

V4- (0.2-0.3) Vs.

where Vs is the volume of the annulus below the packer (up to the bottom).

After the cement hardening period (CLC) has expired, the reservoir is perforated (Fig. 2) and the well drilled in the usual manner.

Example. Initial data for calculating the process.

The conductor is lowered to a depth of 400 m. The production string is lowered to a depth of 2030 m. The reservoir is 10 m thick, its roof is at a depth of 1990 m, the water-oil contact (VOC) is at a depth of 2000 m. Well diameter (in bit) -215 , 9 m. The outer diameter of the column is 146 mm, the inner is 130 mm. The equipment for the bottom of the column is planned as follows:

Shoe В-146 at a depth of 2030 m (at the bottom), TsKOD - at a depth of 2020 m, self-compacting packer (packing part) - at a depth of 1999 m (1 m above the BHK), The column is compressed at 20.0 MPa, then They are cemented with a pure cement mortar with a density of 1850 kg / m3, the clay mud in the well has a density of 1200 kg / m. The grouting is sold in clay. There are no open cracks with intensive absorption of flushing fluid during the drilling interval below the reservoir (therefore, cement slurry based on a cement-water suspension with 50% water content can penetrate only into defects in the borehole wall, large pores, cavernous sections and near-wall fractures of rocks length)

0 It was established (based on the experience of well overhaul) that in this oil-bearing area or field, the volume of cement slurry Vi 0.35 Vs.

5 In wells where aquifers or the flooded plantar of the oil-bearing monolithic formation are non-fractured, paid porous sandstones, cement slurry with a hardening filtrate can be used to crush these strata. This solution in a volume equal to Vi + V2 + Vs is prepared at the end of cementation and pumped into the column and last. In this way, a blocking (water-insulating) screen in a water-saturated formation to a certain depth can be created.

Calculation of the volume of cement-based cement slurry crushed into the under-packer space and, accordingly, the installation height of the shear stop ring. The volume of annular space at a height of 31 m from the bottom to the packer (2030 m - 1999 m) will be

5

Vs - 0.785 (0.21592-0.1462) x 31 0.61m3

Vi - 0.35 Vs 0.213m3.

Based on the conditions of the example, the pressure at the mouth at the end of cementing (P "c) will be RCC A Rgc + Rg,

where D Rgs - the difference in hydrostatic pressure in the pipes in the annulus;

Rg is the pressure loss on hydraulic resistance (2.0 MPa).

 ..,. . RCC

1730 X 1850 +300 X 1200 -2000 X 1200

10000, - ..

+ 20 110 + 20 130 kg / cm2 or 13 MPa,

The volume of cement mortar can be reduced by 5-20% by filtering the liquid phase into the formation. Assume that 20% is filtered out. Then, taking this into account, Vt 0.213 x 1.2 OD56 m3.

The distance between the main stop ring (TsKOD-ohm) and the shear stop ring paradise. . - ... .- .-: vv. : read by the formula hcK.

 : .-: ... .- G T

where FT is the cross-sectional area of the casing.

FT 0.785 x dBK2 0.785 x 0.13.2 - 0.01325 m2.

Then the lawsuit

0.256MJ

19.4 m. Take

0.01325m 20 Mk.-.-. ../. . :.: ..:. .. ..

Thus, a shear stop ring must be installed at a depth of NTscode - he 2020 m - 20 m 2000 m. In order to clearly fix the pressure, the stop-shear stop ring must be cut off at a shear pressure (Pc) lower than the stop pressure by 2 , 0-3.0 MPa and a pressure greater at 1.5-2.0 MPa at the end of cementing, minus the pressure on hydraulic resistance (Pr) inside the column (1.0 MPa), this will be Pc 13.0 + 2.0 -1.0 14 MPa.

Thus, the shear stop ring is equipped with studs for a shear pressure of 14 MPa. Then, the expected value of stop pressure after forcing the solution into the under-packer space will be 14+ 1+ + (2-3) 17-18 MPa.

Conducting the process.

In accordance with the above calculation, the column is equipped and lowered. The accuracy of the installation of the packing element at a depth of 1999 m is checked using

5

0

5

0

5

: -

about 5

0 5

g

geophysical measurements by the tackle and adjust. After this, the cement slurry is prepared and injected with a volume of Vi + N / 2 + Uz. The volume of cement mortar for cementing the annular space, taking into account the conductor shoe overlapping by 100 m, will be Uz 0.213 + 0.1333 + (2030-300) x 0.197x x 1.3 44.646 m (here 1.3 is the correction for wall cavernousness).

After reaching a pressure of 11-12 MPa, the bursting speed is reduced (to fix the shear pressure of the ring at 15-16 MPa). After cutting the stop ring, the pressure is sharply reduced to 12-TK MPa and the forcing of the solution is continued until the stop (17-18 MPa) is reached, i.e., until the completion of the entire cementing operation. After the hardening of the cement, the opening of the formation and well development are carried out by existing methods. ; -

Claims (1)

SUMMARY OF THE INVENTION A method of cementing a production string of pipes in a well with an aquifer below the oil or monolithic oil reservoir with bottom water, including pumping the cement slurry into the string, forcing it into the annulus until the cement plug is seated to the stop ring and creating excess pressure on the formation, characterized in that, in order to improve the quality of cementing due to more reliable sealing of the cement ring in the intervals of water flow underneath With a seam reservoir, the aquifer or part of the oil reservoir containing bottom water is isolated from the oil self-sealing packing unit, the volume of cement equal to the volume of cement squeezed into the aquifer is cut off by placing an additional shear stop ring inside the column, after which an aquifer or flooded bottom of the formation creates a back pressure while at the same time crushing a specified volume of cement into it.