Sidewall well-formation fluid sampler

Claim 2

In a side-wall well-formation fluid sampler of the type run on and controllable over a well-logging cable, said sampler comprising an elongated tool body having a sample-receiving inlet, means on said body for pressing said inlet against a well wall at a desired sampling point, a fluid flow path extending from said inlet through a sample-holding space within said body to an outlet opening into the well bore, remote-indicating fluid pressure and fluid character-testing means in communication with said flow path, means for transmitting to and exhibiting at the ground surface the indications of said pressure and said character-testing means, and a pump in said flow path operable by reciprocating said cable to draw formation fluids through said inlet, flow them along said flow path, and eject them through said outlet into the well bore, the improvement in which said inlet-pressing means comprises wall-engaging shoes movable radially from said body into well-wall contact on two opposite sides of a well bore, a sampling head including said inlet and radially movable with the shoe or shoes contacting one side of said bore, means for applying radial forces from said body to said shoes and said head to press them into well-wall contact on opposite sides of a well with said inlet at said desired sampling point, and lever means for dividing the radial force directed toward said one side of said bore between said head and said shoe or shoes.

Claim 3

A sampler as in claim 1 in which said radial force-applying means comprises a power piston attached to a power-piston rod and surrounded by a power cylinder with which said piston and rod have sliding seals, the ratio of piston-face area to effective rod cross-section area being a greater than unity, a supply of hydraulic fluid at hydrostatic well-fluid pressure, a bulkhead between said fluid supply and said cylinder having a passage to conduct said fluid into said cylinder to act on said piston face, the other face of said piston and the portion of said rod within said cylinder being in communication with a space at low pressure such as atmospheric, the other end of said rOd from said piston being exposed to said hydrostatic pressure, valve means in said passage to control the flow of said hydraulic fluid therethrough, a first cylinder enclosing a first regulating piston exposed to the pressure in said passage between said valve means and said fluid supply, the ratio of face areas of said power and said regulating piston being n, a number substantially greater than unity, a second cylinder enclosing a second regulating piston exposed to hydrostatic pressure and connected to said first regulating piston, the space between said pistons being in communication with said low pressure space, and the ratio of first to second regulating piston face areas being also substantially equal to a, spring means exerting a force F on said coupled regulator pistons opposite to that of said hydraulic fluid pressure acting on said first regulator piston, said regulator piston being coupled to said passage valve means in a sense to close said passage when sufficient hydraulic fluid has flowed to said power cylinder to cause said piston rod to exert a force nF on shoe-setting means coupled thereto.

Claim 4

A sampler as in claim 1 in which said pump comprises an outer barrel and an inner plunger, and said elongated body is formed in two longitudinal sections, that body section carrying said shoes and sampling head including one of saId barrel and plunger, and the other body section being operatively connected to said cable and including the other of said barrel and plunger, whereby said pump operates by reciprocating one of said sections relative to the other by reciprocating said cable.

Claim 5

A sampler as in claim 3 including also releasable lock means holding said barrel and plunger fixed relative to each other, and means controllable from the ground surface for releasing said lock means to permit operation of said pump.

Claim 6

A sampler as in claim 4 in which said controllable releasing means comprises a reversible electric motor, a rod extending axially through said tool body and having a cam surface, cam follower means actuatable by said surface and coupled to said locking means, and coupling means between said motor and said rod to produce movement of said rod and cam surface by said motor to actuate said follower means and thereby cause said lock means to engage or to release said barrel and plunger.

Claim 7

In a sampler as in claim 5 in which said rod has a longitudinal passage extending therethrough, at least one insulated electrical conductor extending through said passage, electrical switch means actuatable by said rod movement, and electrical connector means engaged by said rod movement to extend said insulated electrical conductor to said switch means.

Claim 8

In a sampler as in claim 5 in which said rod is movable axially by said motor through seals from a space at low pressure such as atmospheric and is exposed to said hydrostatic pressure, and including also an annular piston encircling said rod with a face area substantially equal to the sealed cross-sectional area of said rod, a cylinder sealingly surrounding said annular piston, and conduit means for applying hydrostatic pressure to one face of said annular piston, the opposite face being exposed to said low pressure, the force of said annular piston on said rod being substantially equal and opposite to that of the hydrostatic pressure urging said rod toward said low-pressure space.

Claim 9

In a sampler as in claim 5 in which said rod extends through at least the major part of the length of said pump and through two constrictions in said flow path respectively near the two ends of said pump barrel, and means substantially simultaneously forming seals between said rod and said constrictions at one lengthwise position of said rod, whereby the portion of said pump in said flow path between said seals may become a sealed sample-holding chamber.

Claim 10

In a sampler as in claim 3 in which said tool body section carrying said shoes includes an inlet chamber surrounding the inlet to said pump, and through which said pump extends, resilient seals encircling said pump where it passes through the upper and lower ends of said chamber, shear-pin means extending between said chamber and said pump to prevent relative longitudinal movement of said pump and chamber, the lower-end area of said chamber surrounding said pump being larger than the corresponding upper-end area of said chamber by substantially the cross-sectional area of said pump plunger, whereby the suction pressure of said pump within said chamber creates an upward hydraulic force on said chamber to be transmitted to said anchor shoes, said force being substantially equal to the lifting force applied to said cable to reciprocate said pump, and whereby said shear-pin means is substantially unstressed during pumping.

Claim 11

In a sampler as in claim 9 in which said pump inlet chamber surrounds a cylindrical screen coaxial with and surrounding said pump and the inlet aperture thereto, there being an annular space of substantial volume for solids accumulation outside said screen between it and the wall of said chamber.