SU950899A1 - Automatic hole-bottom blowout preventer - Google Patents

Description

(54) AUTOMATIC BETTING TRANSFORMER

one

The invention relates to the field of drilling oil and gas wells, namely, automatic downhole preventers designed to prevent oil and gas emissions that occur during drilling.

A downhole preventer for preventing outliers during drilling is known, which allows temporary separation of formations behind the drill pipe due to concentric installation of overlapping sleeves with three and two rows of flushing channels fixed by shear elements in the housing with combined upper rows of channels 1.

This device does not provide automatic sealing of the wellbore when annular gas flow occurs, which significantly reduces the effi- ciency of the use of the preventer.

An automatic downhole preventer is known, comprising a housing with radial channels blocked by a spool installed inside the housing and an internal differential bushing, which forms an annular cavity with the casing, a bushing that reacts to a decrease in pressure in the annulus, and a sealing element 2 installed on the casing.

The disadvantage of this device is the complexity of the design of its mechanism, which reacts to a decrease in pressure in the annulus of the well.

The purpose of the invention is to simplify the design.

The goal is achieved by the fact that in an automatic Vtu.1ka downhole preventer, which reacts to a decrease in pressure in the annulus, is made differential, mounted on the outer surface of the housing and forms with it a cavity connected to the cavity of the inner differential sleeve, on the upper end 15 of which is installed a clamp .

FIG. 1 shows an automatic downhole preventer during drilling; in fig. 2 - the same at the moment of opening of the holes for smoothing the drilling mud: in FIG. 3 - the same, at the time of closing 20 versts for smoothing the solution, unpacking and opening the holes for direct piping.

The automatic bottomhole preventer will turn on case 1 with radial holes A, B: C and D, with holes C blocked by a check valve 2 and A and D spool 3. The spool is fixed relative to the body with a shear element 4 and equipped with a single-sided cuff 5. Spool 3 has radial holes D and E, axial holes W, annular groove 3 and end grooves I.

On the housing 1, a sealing element b is installed, the outer differential sleeve 7, and inside the housing there is a differential sleeve 8 inside. The internal differential sleeve 8 is equipped with a fitting 9 and has radial holes — filter K. The stops 10 and 11 restrict the movement of the sleeves 7 and 8, and the pin 12 restricts the mixing of the spool 3. The outer 7 and inner 8 differential sleeves form with the housing 1 the cavities L and M, which communicate with each other with a calibrated orifice B and are filled with a viscous liquid. Sleeve 7 and 8, cavities L and M, which communicate with each other with a calibrated orifice B, form a "hydraulic rocker of the mechanism that automatically responds to pressure changes in the annulus of the well.

An automatic bottomhole preventer with threads using the ends of body 1 (not shown) is mounted on the column, i.e. it is an integral part of it.

The device works as follows.

With a short-term increase in pressure in the pipe string preceding the start of circulation of the flushing fluid in the well, the internal differential sleeve 8 perceives this pressure, moves up, expels the fluid from the cavity L through the calibrated orifice B into the cavity M. Viscosity of the liquid filling the cavity L and M, as well as the small diameter of the calibrated orifice B, provide sufficiently slow movement of the sleeves 7 and 8. This slows down the alignment of the apertures - filter K of the sleeve 8 with the openings B of housing 1, i.e. devremennoe operation (blow-up) of the sealing element 6.

When drilling mud circulates in the borehole, the differential bushing 8 returns to its original position under the effect of pressure change created by the brush 9 mounted on it (the fitting can be composite and tailored to specific conditions).

During the descent of the column, the outer differential sleeve 7, experiencing greater pressure than the inner sleeve 8, remains in the initial position. Thus, during the descent of the column, flushing, elaboration and penetration of the wellbore, the preventer is protected from firing.

If, during these operations, an excessively high gas content in the drilling fluid is found, stop the circulation of fluid in the well. The degassing of the drilling fluid reduces its density, and, thus, creates a differential pressure of the annular and intra-column space. The differential sleeve 8 is displaced up to the stop, the holes - the filter K is aligned with the radial holes

body 2, and the drilling fluid through the check valve 2 enters the cavity of the sealing element 6, i.e., the annular space of the well is packed. Simultaneously with the movement of the sleeve 8 upward external differential sleeve 7

shifts down, i.e., an imbalance occurs in the "hydraulic rocker" equilibrium due to the pressure difference between the annular (degassed) and intratubular (intra-column) mud columns.

If the pressure difference between the pillar and annular columns of the fluid, which is necessary for packing, may circulate the flushing fluid in the well, a pressure reducing valve should be installed in the lower part of the drill string.

When annular gas streams occur during tripping, the device operates in the same way as shown above.

After packing, the usual

technology of working with a downhole preventer After starting the ball 13 and landing it on the lower seat of the spool 3, the pins 4 are cut off, and the spool moves down to the stop in the studs 12, and the circulation holes G and D are aligned to allow replacement (empty), degassed drilling solution above the downhole preventer.

After the drilling fluid has settled above the packer, a shark 14 is allowed, which, when seated on the upper saddle of the spool 3, displaces it all the way into the internal protrusion of the body, destroying the pins 12 and blocking the circulation holes of the hull G. When the spool 3 reaches its final position, the cavity of the sealing element 6, skirting the petal of the cuff 5, comes out through the holes A and E of the spool into the annular space. Axial bore holes, annular groove 3 and end grooves And spool 3

provide an opportunity to perform the necessary technological operations after the fluid is released from the working cavity of the sealing element to replace the degassed solution under the downhole preventer and further drill the well, and also exclude the possibility of overflow of the drilling fluid when lifting the column.

The proposed design provides the possibility of creating an automatic downhole preventer of high reliability and operational manufacturability. The widespread use of such a preventer in addition to wellhead blowout equipment will speed up the degassing of drilling mud, eliminate griffon formation and emergency situations associated with long-term access of gas to wellhead equipment.

Claims (2)

1. USSR author's certificate number 489858, cl. E 21 V 33/12, 1969. 2. USSR author's certificate number 747978, cl. E 21 V 33/12, 1976. i Fig1 FIG. 2