초록 ▼

In common with conventional testing tools for this purpose, the present tool incorporates a central mandrel carrying a pair of vertically spaced packers which are expandable by fluid pressure, which mandrel forms a longitudinal bore having an outlet communicating with the annular space between the p

In common with conventional testing tools for this purpose, the present tool incorporates a central mandrel carrying a pair of vertically spaced packers which are expandable by fluid pressure, which mandrel forms a longitudinal bore having an outlet communicating with the annular space between the packers. In contradistinction to the prior tools, the bow spring and slips suspending assembly of the prior tools has been eliminated. Instead, the packers themselves are relied on to suspend or fix the tool in the tubing. To achieve this end, a novel valve assembly has been provided to control the admittance and bleeding off of pressurized fluid into the annular space. The valve assembly is adapted to first admit pressurized fluid into the annular space to set the packers and pressure test the tubing wall between the packers at relatively high pressure, for example 5000 psi. The valve assembly is further adapted to cooperate in bleeding off the pressure from the annular space until it just exceeds that amount required to hold the packers set, say 600 psi; the valve assembly then automatically closes, to trap the 600 psi pressure in the annular space so that the packers maintain the tool in a suspended state. A second stand of tubing can then be added to the tested stand and lowered into the well bore until the second stand\s upper end seats in the wellhead. A cable overshot is then used to open the valve assembly, to bleed off the 600 psi, following which the packers collapse and the tool can be retrieved.

대표청구항 ▼

A retrievable hydrostatic testing tool for pressure testing a stand of wellbore pipe for leaks using pressurized fluid from a source, said tool comprising: a valve assembly; a pair of vertically spaced apart packers; and means for carrying the packers, said carrying means being connected at its uppe

A retrievable hydrostatic testing tool for pressure testing a stand of wellbore pipe for leaks using pressurized fluid from a source, said tool comprising: a valve assembly; a pair of vertically spaced apart packers; and means for carrying the packers, said carrying means being connected at its upper end to the lower end of the valve assembly; said packers being expandable by fluid pressure applied between the packers into sealing and tool-suspending relationship with the inner surface of the stand; said carrying means forming a first bore extending longitudinally therethrough from its upper end and having an outlet located between the packers and communicating with the annular space formed between the carrying means, the packers, and the stand, whereby pressurized fluid may be introduced through the first bore and outlet into the annular space for expansion of the packers and pressure testing of the stand; said valve assembly comprising a valve body forming a closed chamber and a second bore connecting the lower end of the chamber with the first bore, means, associated with the valve body and connectable with the source, for admitting pressurized fluid to the lower end of the chamber and for bleeding off pressurized fluid from the lower end of the chamber, a slider valve member positioned in the chamber and adapted to slide vertically therein between a seated position, in which it contacts the valve body to close the second bore, and an unseated position, in which the second bore is left open to communicate with the lower end of the chamber, the lower end of said valve member being configured to supply a surface against which pressure present in the lower end of the chamber may act to exert an upward force on the valve member, means for interconnecting with an overshot, said means being connected with the slider valve member and extending upwardly out of the valve body in sliding association therewith, and means for normally urging the slider valve member downwardly to the seated position with sufficient force to overcome the upward force generated by fluid pressure present in the lower end of the chamber and the annular space, which fluid pressure is just sufficient to maintain the packers expanded so that they fix the testing tool against slipping downwardly, said urging means being operative to permit the slider valve member to be unseated when said fluid pressure reaches a value substantially greater than said packer expansion pressure but substantially less than the desired testing pressure, whereby pressurized fluid may be admitted into the lower end of the chamber to increase the pressure therein until the slider valve member is unseated against the resistance of the urging means, to thereby admit the pressurized fluid into the annular space to expand the packers and establish a desired testing pressure therebetween, and whereby the fluid pressure in the lower end of the chamber and annular space may thereafter be reduced until the urging means moves the slider valve member to the seated position, thereby trapping fluid, in the annular space, which has a sufficient pressure to maintain the packers in the expanded state, whereby the packers function to fix the tool in the stand, thereby making it possible to attach a second stand of pipe to the first stand and to lower the second stand into the wellbore with the testing tool suspended in the first stand and thereafter to lower an overshot through the second stand to grasp the interconnecting means and pull said interconnecting means and attached slider valve member upwardly, to release the trapped pressure and collapse the packers, whereby the tool may be retrieved to the top of the second stand.