SU1465582A1 - Method of cementing large-diameter casings - Google Patents

Abstract

The invention relates to mining. The goal is to increase the reliability of the cementing process when pumping cement mortar through the drill string by preventing it from sticking with hardened cement mortar. In the bottom hole, a casing string is lowered, inside which a drill string is installed above the bottom of the well. Then, the annular space is sealed at the wellhead and cement mortar is pumped into the anchoring space until it appears at the wellhead. A pressure fluid is pumped through the valve in the BC and the BC is sealed to the wellhead, closing the valve. Through another valve, additional squeezing fluid is supplied to the annular space through the wellhead until the level of the dessy mortar in it is lower than the BC shoe. The additional flow volume of the squeeze fluid and the distance to the fur with the shoes of the casing and BC is determined from the ratios given in the invention. 2 hp f-ly, 1 ill. (L

Description

one

The invention relates to mining and relates to methods for cementing large diameter boreholes.

The aim of the invention is to improve the reliability of the cementing process when pumping cement mortar through the drill string by preventing it from sticking with hardened cement mortar.

The drawing shows a well in the process of implementing the method according to the invention.

The method includes a casing with a diameter D in the well bottomhole, installation of a drill hole inside it.

columns with diameter d, sealing the annular space, pumping cement mortar into the fixed pr - space, filling the drill string with the squeezing fluid and supplying the squeezing fluid through it into the annular space, the drill string being installed above the borehole bottom with a distance between the shoes A and B of the casing and drillstring h, and after filling the drillstring with the squeezing fluid, the wellhead is sealed and an additional supply of squeezing fluid in the volume bV is performed through the wellhead kvazhiny to reduce it

level of cement mortar UCR below the drill string drill

An additional supply of squeezing fluid can be produced in the volume, the limit of which is consumed from the ratio

H E P .-. &Amp; -

 TO

Where

H g

Р well depth, m; volume per meter of casing 10

NOI columns, m

pressure at the end of squeezing, Mlla; K - coefficient of volume compression,

MPa.

The distance between the casing and drillpipe shoes is determined by the relation:

(i-2),

de 1-2 15

20

25

height of cement stack-.

on m

The method is carried out as follows.

After the casing has been lowered to the design depth, preliminary calculations are made to determine the depth of the drill string and the additional volume VV. For this task, the pressure in,;

P-HCbzM

, ten

WHERE X c, y - density of cement and drilling mud, kg / cm.jg

Claims (3)

I, the pressure P, determine the additional volume uV and the distance between the column shoes h. In view of the size h, the drill string is lowered And sealed the annular space of tTBo at the mouth ,. Cement f acTBOp is pumped through valve 1 before its appearance at the mouth, then separation cork B is released and through valve 2 at closed Cranes 1 and 3, flush fluid is pumped until the plug is seated. The shear saddle is sealed at the mouth, the valve 2 is closed. , Through valve 3, an additional volume of squeezing fluid V is pumped, the level of cement growth1. The method of cementing large-diameter casing, including lowering into the well to the bottom of the casing and installing a drill string inside it, sealing the annular space into the wellhead, pumping cement mortar in the storage space, filling the drill string with the squeezing fluid and supplying the squeezing fluid through it into the annular space, in order to increase cementing process reliability when injecting cement slurry through the drill string by preventing its stuck solidified grout, positioned over the drill string downhole, after squeezing the fluid filling the drill Kokontsev pro- 30 m Lonna derivatives in its sealing the wellhead and an additional supply of squeezing fluid into the annular space through the wellhead is performed until the level of cement slurry in it drops below the drill string shoe. 2. A method according to claim 1, characterized in that the additional flow of the squeezing fluid is produced in a volume determined from 40 Sheni & V H-g-P 45 where & V is the volume additionally filed liquids, N - well depth, m; g - the volume of the running meter of the casing, m P 50 K pressure at the end of pushing, MPa; volumetric compression ratio, MPa. 3. Method POP.1, characterized in that the distance between the casing and drill string shoes gg is determined from the ratio the UCR floor will be reduced to UCR, i.e. After the injection, the faucet $ 3 is closed and, through the faucet 2, the pressure is pumped up to the cut-off of the saddle by the injection of the flushing fluid. At this end the cementing process is completed. After the cement mortar begins to set, the drill string is backwashed, and then removed from the well after depressurization of the annulus. Invention Formula 2. The method according to claim 1, in that, prior to the supply of the pumping liquid in the volume, Sheni & V H-g-P where & V is the volume additionally filed liquids, N - well depth, m; g - the volume of the running meter of the casing, m P 50 K pressure at the end of pushing, MPa; volume compression ratio MPa. 3. Method POP.1, characterized in that the distance between the casing and drill string shoes gg is determined from the ratio (1-2), where h is the distance between the shoes, m; 5. 1465582 H - well depth, m; P - pressure at the end of pressure, MPa; 1-2 2 K - coefficient of volume compression, MPa; height of cement glass, m