RU2067155C1 - Device for isolation of lost circulation zones - Google Patents

Abstract

FIELD: isolation of lost circulation zones. SUBSTANCE: device for isolation of lost circulation zones includes cylindrical hollow body with landing socket and shutoff member in form of ball with spring-loaded shank made in form of branch pipe which forms together with body a circular hollow. Device has piston arranged in the upper part of circular hollow and rigidly connected with branch pipe. Device also has seat with milled recesses. Seat is engageable with shutoff member located under it and made to communicate body hollow above shutoff member with its hollow under the shutoff member through milled recess and hollow in device working position. EFFECT: higher efficiency. 1 dwg

Description

 The invention relates to well drilling and relates to methods for isolating washout absorption zones.

 A device for isolating the absorption zones of washing liquid (1).

 However, this device is characterized by a large consumption of cement slurry, especially in conditions of abnormally low reservoir pressure.

 The closest analogue of the invention is a device for isolating the zones of absorption of washing liquid, including a cylindrical hollow body with a seat socket and a locking element with a spring-loaded shank (2).

 The known device provides for relieving pressure from the cemented area.

 However, this device has a disadvantage due to the low reliability of its operation.

 The technical result of the invention is to increase the reliability of the device.

 The necessary technical result is achieved by the fact that in the device for isolating the zones of absorption of flushing fluid, including a cylindrical hollow body with a seating socket and a locking element with a spring-loaded shank, the latter is made in the form of a pipe forming an annular cavity with the body, has a piston located in the upper part of the annular cavity, and rigidly connected with the pipe, and a saddle with milled grooves, interacting with a locking element placed under it and configured to communicate the cavity casing above the closing element with its cavity under the locking element through the milled grooves and tube cavity in the working position of the device, wherein the locking member is a ball.

 The drawing shows a device.

 The device includes a cylindrical hollow body 1 having a threaded joint in the upper and lower parts. A landing seat 2 and a locking element 3 with a spring-loaded shank 4 are installed in the housing. The shank 4 is made in the form of a pipe forming an annular cavity 5 with the housing 1. The device has a piston 6 located in the upper part of the annular cavity 5 and rigidly connected to the pipe 4. The device also has a saddle 7 with milled grooves 8, interacting with the locking element 3, placed under this locking element and configured to communicate the cavity of the housing under the locking element with its cavity above the locking element through milled grooves 8 and the cavity of the pipe in the working position of the device. The locking element 3 is made in the form of a ball.

 The device operates as follows.

 A packer and a device for isolating the absorption zones of drilling fluid are lowered into the well on the drill pipes. The packer is installed as close to the absorption zone as possible in order to prevent fluid flow from overlying formations and to prevent dilution of the cement mixture.

The estimated installation depth of the device is determined by the formula
L _calc 10 P _open , (m)
where L _{calculation the} estimated installation depth of the packer, m;
P _open valve opening pressure, MPa.

 Depth of installation of the valve higher than estimated is unacceptable.

где Р_откр давление открытия клапана, МПа;
Н_ст статический уровень в скважине, м;
h_ц.ст общая высота цементного моста для перекрытия зоны поглощения, м;
γ_ц.р. удельный вес тампонирующей смеси или цементного раствора, г/см³,
ΔP = P_пл.- P_заб. разность пластового и забойного давлений по окончании продавки, противодействующая самопроизвольному движению цементного раствора в пласт, принимается равной 1,0-1,5 МПа.The estimated valve opening pressure is determined by the formula

where P _open valve opening pressure, MPa;
N _{st the} static level in the well, m;
h _{cst the} total height of the cement bridge to overlap the absorption zone, m;
γ _ts.r. the specific gravity of the plugging mixture or cement mortar, g / cm ³ ,
ΔP = P _pl. - P _zab. the difference between the reservoir and bottomhole pressures at the end of the sale, counteracting the spontaneous movement of the cement slurry into the reservoir, is taken to be 1.0-1.5 MPa.

 Upon completion of the descent of the drill pipe, the packer is landed. Then make the injection and sale of cement mixture under the design pressure.

 At the end of the process of selling fluid, the device automatically closes. When this occurs, the cessation of the progress of the grouting mixture, as well as the equalization of reservoir and bottomhole pressures, occurs.

 Then the well is left to wait for the hardening of cement (OZP).

Claims (1)

 A device for isolating the zones of absorption of flushing fluid, comprising a cylindrical hollow body with a seat socket and a locking element with a spring-loaded shank, characterized in that the shank is made in the form of a pipe forming an annular cavity with the body, has a piston located in the upper part of the annular cavity and rigidly connected with a nozzle, and a saddle with milled grooves, interacting with a locking element placed under it with the possibility of communicating the body cavity above the locking element with its about the cavity under the locking element through the milled grooves and the cavity of the pipe in the working position of the device, while the locking element is made in the form of a ball.