Methods and apparatus for testing earth formations composed of particles of various sizes

Claim 3

The method of claim 1 wherein said first and second filter passages are respectively arranged as separated elongated slits in said filtering means.

Claim 4

The method of claim 1 wherein said first and second filter passages are arranged as a single elongated slit in said filtEring means having an enlarged portion defining said first filter passage and a reduced portion defining said second filter passage.

Claim 7

The method of claim 4 further including the step of: measuring at least one property of connate fluids passing through said filtering means for determining one or more characteristics of said earth formations.

Claim 8

The method of claim 4 further including the step of: collecting at least one sample of connate fluids passing through said filtering means.

Claim 9

The method of claim 4 further including the steps of: obtaining at least one measurement of the pressure of connate fluids passing through said filtering means for determining one or more characteristics of said earth formations; and, thereafter, collecting at least one sample of connate fluids passing through said filtering means.

Claim 10

Formation-testing apparatus adapted for suspension in a borehole having mudcake lining the walls thereof adjacent to earth formations containing producible connate fluids and comprising: a body having a fluid passage adapted to receive connate fluids; fluid-admitting means on said body including a fluid entry coupled to said fluid passage and adapted to be engaged with a borehole wall for isolating a surface thereof from borehole fluids; means selectively operable for positioning said fluid-admitting means against a borehole wall to place said fluid entry in communication with earth formations beyond the isolated wall surface of said borehole wall; and fluid-filtering means cooperatively arranged between said fluid passage and said fluid entry for initially passing mudcake particles displaced from said isolated wall surface on through said filtering means into said fluid passage and operable thereafter whenever loose formation particles of a size smaller than such mudcake particles are eroded from said isolated wall surface for collecting such loosened smaller formation particles as connate fluids pass on through said filtering means into said fluid passage.

Claim 11

Formation-testing apparatus adapted for suspension in a borehole having mudcake lining the walls thereof adjacent to earth formations containing producible connate fluids and comprising: a body having a fluid passage adapted to receive connate fluids; fluid-admitting means on said body including a fluid entry coupled to said fluid passage and adapted to be engaged with a borehole wall for isolating a surface thereof from borehole fluids; means selectively operable for positioning said fluid-admitting means against a borehole wall to place said fluid entry in communication with earth formations beyond the isolated wall surface of said borehole wall; and fluid-filtering means cooperatively arranged between said fluid passage and said fluid entry for initially passing mudcake particles displaced from said isolated wall surface on through said filtering means into said fluid passage and operable thereafter whenever loose formation particles of a size smaller than such mudcake particles are eroded from said isolated wall surface for collecting such loosened smaller formation particles as connate fluids pass on through said filtering means into said fluid passage.

Claim 12

The formation-testing apparatus of claim 8 wherein said fluid-filtering means include: a filter member having at least one reduced filter passage sized to retain loose formation particles, and at least one enlarged filter passage in parallel flow relationship with said reduced filter passage sized to pass mudcake particles and cooperatively arranged for collecting loosened formation particles in a bridge across said enlarged filter passage for reducing the flow of connate fluids therethrough so that at least a major portion of connate fluids will then be directed through said reduced filter passage.

Claim 13

The formation-testing apparatus of claim 9 wherein said filter passages are arrangEd as a single elongated slit having an enlarged end portion for defining said enlarged filter passage and a reduced end portion for defining said reduced filter passage.

Claim 14

The formation-testing apparatus of claim 9 further including: means selectively operable after disengagement of said fluid-admitting means from said borehole wall for displacing from said flud entry any loosened formation materials previously collected as a bridge across said enlarged filter passage.

Claim 15

The formation-testing apparatus of claim 9 further including: pressure-measuring means coupled to said fluid passage and adapted for providing at least one measurement representative of the pressure of connate fluids in said fluid passage.

Claim 16

The formation-testing apparatus of claim 9 further including: sample-collecting means on said body and selectively operable for obtaining a sample of connate fluids in said fluid passage.

Claim 17

The formation-testing apparatus of claim 9 further including: pressure-measuring means coupled to said fluid passage and adapted for providing at least one measurement representative of the pressure of connate fluids in said fluid passage; and sample-collecting means on said body and selectively operable for obtaining a sample of connate fluids in said fluid passage.

Claim 18

The formation-testing apparatus of claim 14 further including: means selectively operable after disengagement of said fluid-admitting means from said borehole wall for displacing from said fluid entry any loosened formation materials previously collected as a bridge across said enlarged filter passage.

Claim 19

Formation-testing apparatus adapted for suspension in a borehole having mudcake lining the walls thereof adjacent to earth formations containing producible connate fluids and comprising: a body having a fluid passage adapted to receive connate fluids; fluid-admitting means on said body and including a fluid-sampling member having an inlet passage adapted to be engaged with a borehole wall for isolating a surface thereof from borehole fluids and an outlet passage downstream of said inlet passage and coupled to said fluid passage; means selectively operable for positioning said fluid-sampling member against a borehole wall to place said inlet passage into communication with earth formations beyond the isolated wall surface of said borehole; and filtering means cooperatively arranged on said fluid-sampling member for intercommunicating said inlet and outlet passages and including means defining a chamber adapted for collecting loose formation particles entering said inlet passage, means defining at least one enlarged filter passage between said chamber and said outlet passage and selectively sized to initially pass mudcake particles entering said particle-collecting chamber into said outlet passage as well as to subsequently develop a bridge of loosened formation particles across said enlarged filter passage whenever such entering formation particles are collected in said particle-collecting chamber, and means defining at least one reduced filter passage upstream of said enlarged filter passage and selectively sized to retain such loosened formation particles without halting the flow of connate fluids between said inlet and outlet passages.

Claim 20

Formation-testing apparatus adapted for suspension in a borehole having mudcake lining the walls thereof adjacent to earth formations containing producible connate fluids and comprising: a body having a fluid passage adapted to receive connate fluids; fluid-admitting means on said body and including a fluid-sampling member having an inlet passage adapted to be engaged with a borehole wall for isolating a surface thereof from borehole fluids and an outlet passage downstream of said inlet passage and coupled to said fluid passage; means selectively operable for positioning said fluid-sampling member against a borehole wall to place said inlet passage into communication with earth formations beyond the isolated wall surface of said borehole; and filtering means cooperatively arranged on said fluid-sampling member for intercommunicating said inlet and outlet passages and including means defining a chamber adapted for collecting loose formation particles entering said inlet passage, means defining at least one enlarged filter passage between said chamber and said outlet passage and selectively sized to initially pass mudcake particles entering said particle-collecting chamber into said outlet passage as well as to subsequently develop a bridge of loosened formation particles across said enlarged filter passage whenever such entering formation particles are collected in said particle-collecting chamber, and means defining at least one reduced filter passage upstream of said enlarged filter passage and selectively sized to retain such loosened formation particles without halting the flow of connate fluids between said inlet and outlet passages.

Claim 21

The formation-testing apparatus of claim 16 wherein said fluid-sampling member is tubular with a forward portion thereof defining said inlet passage, said outlet passage includes an inwardly-opening fluid chamber formed in an intermediate portion of said fluid-sampling member, and said filtering means include a filter member covering the entrance of said inwardly-opening fluid chamber and having a forward portion with said reduced filter passage therein and a rearward portion with said enlarged filter passage therein and defining at least part of a side wall of said particle-collecting chamber.

Claim 22

The formation-testing apparatus of claim 17 wherein said filter passages are separated from oNe another.

Claim 23

The formation-testing apparatus of claim 17 wherein said filter passage are joined to one another by an intermediate filter passage having a width less than that of said enlarged filter passage.

Claim 24

The formation-testing apparatus of claim 17 wherein said filter passages are joined to one another by an intermediate filter passage having a width less than that of said enlarged filter passage and greater than that of said reduced filter passage.

Claim 25

The formation-testing apparatus of claim 17 further including: a piston member coaxially arranged in said fluid-sampling chamber for movement between a retracted position in the rearward portion thereof to define the rear wall of said particle-collecting chamber and a normal extended position in said forward portion of said fluid-sampling member to block said inlet passage; and means coupled to said piston member and selectively operable for moving said piston member to its retracted position following engagement of said fluid-sampling member with a borehole wall to admit connate fluids into said inlet passage and for returning said piston member to its extended position following disengagement of said fluid-sampling member from a borehole wall to expel any lossened formation materials previously collected as a bridge across said enlarged filter passage from said fluid-sampling member.

Claim 26

Formation-testing apparatus adapted for suspension in a borehole having mudcake lining the walls thereof adjacent to earth formations containing producible connate fluids and comprising: a body having a first fluid passage adapted to receive connate fluids; fluid-admitting means on said body and including a fluid-sampling member having a tubular forward portion adapted to be engaged with a borehole wall for isolating a surface thereof from borehole fluids; means selectively operable for positioning said fluid-sampling member against a borehole wall to establish communication with earth formations therebeyond; first means adapted for limiting the entrance of loose formation particles into said first fluid passage including a second fluid passage in said fluid-sampling member and coupled to said first fluid passage, and filtering means cooperatively arranged on a wall of said fluid-sampling member for controllably communicating said second fluid passage with said tubular forward portion and including enlarged filter passage means selectively sized to initially pass mudcake particles entering said fluid-sampling member as well as to subsequently develop a bridge of loosened formation particles across said enlarged filter passage means whenever such formation particles enter said fluid-sampling member and reduced filter passage means upstream of said enlarged filter passage means and selectively sized for retaining loosened formation particles within said fluid-sampling member as filtered connate fliuds pass through said filtering means into said second fluid passage; second means adapted for controlling the entrance of particles into said fluid-sampling member and including a piston member coaxially arranged in said fluid-sampling member for movement past said filtering means between an advanced position within said tubular forward portion ahead of said reduced filter passage means blocking communication into said fluid-sampling member and a retracted position to the rear of said enlarged filter passage means for uncovering said filtering means and defining a space adjacent to said enlarged filter passage means for collecting loosened formation particles entering said tubular forward portion; and piston-control cooperatively arranged for selectively moving said piston member back and forth between its said advanced and retracted positions.

Claim 27

Formation-testing apparatus adapted for suspension in a borehole having mudcake lining the walls thereof adjacent to earth formations containing producible connate fluids and comprising: a body having a first fluid passage adapted to receive connate fluids; fluid-admitting means on said body and including a fluid-sampling member having a tubular forward portion adapted to be engaged with a borehole wall for isolating a surface thereof from borehole fluids; means selectively operable for positioning said fluid-sampling member against a borehole wall to establish communication with earth formations therebeyond; first means adapted for limiting the entrance of loose formation particles into said first fluid passage including a second fluid passage in said fluid-sampling member and coupled to said first fluid passage, and filtering means cooperatively arranged on a wall of said fluid-sampling member for controllably communicating said second fluid passage with said tubular forward portion and including enlarged filter passage means selectively sized to initially pass mudcake particles entering said fluid-sampling member as well as to subsequently develop a bridge of loosened formation particles across said enlarged filter passage means whenever such formation particles enter said fluid-sampling member and reduced filter passage means upstream of said enlarged filter passage means and selectively sized for retaining loosened formation particles within said fluid-sampling member as filtered connate fliuds pass through said filtering means into said second fluid passage; second means adapted for controlling the entrance of particles into said fluid-sampling member and including a piston member coaxially arranged in said fluid-sampling member for movement past said filtering means between an advanced position within said tubular forward portion ahead of said reduced filter passage means blocking communication into said fluid-sampling member and a retracted position to the rear of said enlarged filter passage means for uncovering said filtering means and defining a space adjacent to said enlarged filter passage means for collecting loosened formation particles entering said tubular forward portion; and piston-control cooperatively arranged for selectively moving said piston member back and forth between its said advanced and retracted positions.

Claim 28

The formation-testing apparatus of claim 22 wherein said second fluid passage includes an annular chamber formed around an intermediate interior wall portion of said fluid-sampling member between said advanced and retracted positionS of said piston member; and said filtering means include a tubular filter member coaxially mounted in said fluid-sampling member around said annular chamber and sized for passage of said piston member as it moves between its said positions.

Claim 29

The formation-testing apparatus of claim 23 wherein said filter passage means are comprised of a plurality of longitudinally-oriented slits circumferentially spaced around said filter member and respectively having enlarged rearward portions defining said enlarged filter passage means and reduced forward portions defining said reduced filter passage means.

Claim 30

The formation-testing apparatus of claim 24 wherein said longitudinally-oriented slits are symmetrically tapered between said enlarged rearward portions and said reduced forward portions.

Claim 31

The formation-testing apparatus of claim 23 wherein said filter passage means are comprised of a plurality of circumferentially-oriented slits spaced longitudinally along said filter member with at least the rearwardmost ones of said slits being wider than at least the forwardmost ones of said slits for respectively defining said enlarged filter passage means and said reduced filter passage means.

Claim 32

The formation-testing apparatus of claim 26 wherein all of said slits ahead of said wider rearwardmost slits are of an equal width which is narrower than the width of said wider rearwardmost slits.

Claim 33

The formation-testing apparatus of claim 22 further including: sealing means cooperatively arranged on said fluid-admitting means around said tubular forward portion and adapted for packing-off a borehole wall around said tubular forward portion.

Claim 34

The formation-testing apparatus of claim 22 further including: means cooperatively mounting said fluid-sampling member on said body for movement relative thereto between a laterally-extended position and a retracted position; and control means cooperatively arranged for selectively moving said fluid-sampling member back and forth between its said extended and retracted positions.

Claim 35

The formation-testing apparatus of claim 22 further including: sample-receiving means on said body and adapted for receiving filtered connate fluids entering said first fluid passage; and control means cooperatively arranged for selectively coupling said sample-receiving means to said first fluid passage.

Claim 36

The formation-testing apparatus of claim 22 further including: pressure-monitoring means for providing indications at the surface indicative of the pressure of connate fluids in said first fluid passage.

Claim 37

The formation-testing apparatus of claim 22 further including: a wall-engaging member movably mounted on said body on the opposite side thereof from said forward portion of said fluid-sampling member; and piston means cooperatively coupled to said wall-engaging member for moving said wall-engaging member between an extended wall-engaging position and a retracted position against said opposite body side to respectively engage and disengage said fluid-admitting means with and from a borehole wall.

Claim 38

The formation-testing apparatus of claim 22 further including: means cooperatively coupling said fluid-sampling member to said body for movement relative to one side thereof between a laterally-extended position and a retracted position; and piston means cooperatively coupled to said fluid-sampling member for moving said fluid-sampling member between its said laterally-extended position and its said retracted position to respectively engage and disengage said fluid-sampling member with and from a borehole wall.

Claim 39

The formation-testing apparatus of claim 33 further including: a wall-engaging member movably mounted on said body on the opposite side thereof; and piston means cooperatively coupled to said wall-engaging position and a retracted position against said opposite body side upon movement of said fluid-sampling member between its said positions.