Apparatus and method for measuring fluid gel strength

Claim 1

An apparatus for measuring the properties of a liquid which comprises: (a) a nonhorizontal conduit positioned to conduct liquid therethrough, (b) means for measuring the pressure differential between two vertically spaced locations in said conduit, (c) means for flowing liquid through said conduit at a rate where the shear rate of the flowing liquid is in the range of greater than zero to about 20 sec -1 , (d) means for cyclically interrupting flow of liquid through said conduit to provide a flow interval and a static interval, and (e) means for measuring the differential pressure between said spaced locations during the static interval.

Claim 2

An apparatus for measuring the properties of a liquid which comprises: (a) a nonhorizontal conduit positioned to conduct liquid therethrough, (b) means for measuring the pressure differential between two vertically spaced locations in said conduit, (c) means for flowing liquid through said conduit at a rate where the shear rate of the flowing liquid is in the range of greater than zero to about 20 sec -1 , (d) means for cyclically interrupting flow of liquid through said conduit to provide a flow interval and a static interval, and (e) means for measuring the differential pressure between said spaced locations during the static interval.

Claim 9

An apparatus for measuring fluid properties comprising: (a) a longitudinal conduit positioned in a nonhorizontal attitude, (b) a first flexible isolation diaphragm having an inner surface communicating with said conduit and an outer surface communicating with a chamber containing a noncompressible fluid, (c) a second isolation diaphragm having an inner surface communicating with said conduit and an outer surface communicating with a chamber containing a noncompressible fluid, (d) means operably associated with said conduit for moving a fluid upwardly through said conduit at a controlled rate where the shear rate of the flowing column of greater than zero to about 20 sec -1 , interrupting the flow of the fluid so that said fluid is alterntely flowed through said conduit and held therein without flow, (e) differential pressure transducer means communicating with said outer chambers for measuring the pressure difference in said sample fluid in the conduit between said first and second isolation diaphragms, (f) means operably associated with said differential pressure transducer for indicating the pressure difference in said sample fluid in the conduit between said first and second isolation diaphragms, (g) means for cycling fluid flow through said conduit at a predetermined frequency, and (h) means for comparing the pressure difference in said sample fluid when said fluid is held in said conduit without flow indicating true density and when the fluid is flowing indicating an apparent density comprising the true density and a frictional pressure gradient density, said frictional pressure gradient density being proportional to the gel strength of said fluid.

Claim 10

An apparatus for measuring fluid properties comprising: (a) a longitudinal conduit positioned in a nonhorizontal attitude, (b) a first flexible isolation diaphragm having an inner surface communicating with said conduit and an outer surface communicating with a chamber containing a noncompressible fluid, (c) a second isolation diaphragm having an inner surface communicating with said conduit and an outer surface communicating with a chamber containing a noncompressible fluid, (d) means operably associated with said conduit for moving a fluid upwardly through said conduit at a controlled rate where the shear rate of the flowing column of greater than zero to about 20 sec -1 , interrupting the flow of the fluid so that said fluid is alterntely flowed through said conduit and held therein without flow, (e) differential pressure transducer means communicating with said outer chambers for measuring the pressure difference in said sample fluid in the conduit between said first and second isolation diaphragms, (f) means operably associated with said differential pressure transducer for indicating the pressure difference in said sample fluid in the conduit between said first and second isolation diaphragms, (g) means for cycling fluid flow through said conduit at a predetermined frequency, and (h) means for comparing the pressure difference in said sample fluid when said fluid is held in said conduit without flow indicating true density and when the fluid is flowing indicating an apparent density comprising the true density and a frictional pressure gradient density, said frictional pressure gradient density being proportional to the gel strength of said fluid.

Claim 14

An apparatus for measuring the properties of liquid which comprises: (a) a conduit positioned in a nonhorizontal attitude and adapted to conduct liquid therethrough; (b) means for measuring pressure differential between two vertically spaced locations positioned along said conduit; (c) an inlet line connected to one end of said conduit; (d) a discharge line connected to the other end of said conduit; (e) a bypass line interconnecting said inlet line and said discharge line; (f) valve means for alternately directing flow through said conduit and said bypass line; (g) a back pressure valve connected to said discharge line downstream of said bypass line connection; (h) pump means connected to said inlet line upstream of said bypass line, said pump means being adapted to pump liquid continuously during measurement of said liquid, said pump means adapted to pump liquid through said conduit at a flow rate where the shear rate of the flowing liquid is in the range of greater than zero to about 20 sec -1 , and (i) means for comparing the pressure differential measured when the fluid is flowing through the bypass line indicating a true density and when said fluid is flowing through said conduit indicating an apparent density comprising the true density and a frictional pressure gradient density, said frictional pressure gradient density being proportional to the gel strength of said fluid.

Claim 15

An apparatus for measuring the properties of liquid which comprises: (a) a conduit positioned in a nonhorizontal attitude and adapted to conduct liquid therethrough; (b) means for measuring pressure differential between two vertically spaced locations positioned along said conduit; (c) an inlet line connected to one end of said conduit; (d) a discharge line connected to the other end of said conduit; (e) a bypass line interconnecting said inlet line and said discharge line; (f) valve means for alternately directing flow through said conduit and said bypass line; (g) a back pressure valve connected to said discharge line downstream of said bypass line connection; (h) pump means connected to said inlet line upstream of said bypass line, said pump means being adapted to pump liquid continuously during measurement of said liquid, said pump means adapted to pump liquid through said conduit at a flow rate where the shear rate of the flowing liquid is in the range of greater than zero to about 20 sec -1 , and (i) means for comparing the pressure differential measured when the fluid is flowing through the bypass line indicating a true density and when said fluid is flowing through said conduit indicating an apparent density comprising the true density and a frictional pressure gradient density, said frictional pressure gradient density being proportional to the gel strength of said fluid.

Claim 16

A method for measuring the properties of a fluid, comprising: (a) measuring the pressure of a static column of said fluid at two vertically spaced points, (b) determining the difference in pressure between said points to thereby indicate the true density of said fluid, (c) measuring the pressure of a flowing column of said fluid at said two points said flowing column having a flow rate where the shear rate of the flowing fluid is in the range of greater than zero to about 20 -1 , (d) determining the difference in pressure between said points during flow to thereby indicate an apparent density comprising the true density and a frictional pressure gradient density, said frictional pressure gradient density being proportional to the gel strength of said fluid.

Claim 17

A method for measuring the properties of a fluid, comprising: (a) measuring the pressure of a static column of said fluid at two vertically spaced points, (b) determining the difference in pressure between said points to thereby indicate the true density of said fluid, (c) measuring the pressure of a flowing column of said fluid at said two points said flowing column having a flow rate where the shear rate of the flowing fluid is in the range of greater than zero to about 20 -1 , (d) determining the difference in pressure between said points during flow to thereby indicate an apparent density comprising the true density and a frictional pressure gradient density, said frictional pressure gradient density being proportional to the gel strength of said fluid.

Claim 22

A method of measuring the properties of a fluid comprising the steps of: (a) flowing a fluid through a substantially vertical conduit, (b) terminating said flow to retain a static column of fluid in said conduit, (c) measuring the pressure of said static column of fluid at vertically spaced points in said conduit, (d) determining the difference in pressure between said points to indicate the true density of said fluid, (e) restarting said flow of fluid and flowing said fluid at a flow rate where the shear rate of the flowing fluid is in the range of greater than zero to about 20 sec -1 , (f) measuring the pressure of said flowing fluid at said points, and (g) determining the difference in pressure between said points during flow to indicate an apparent density comprising the true density and a frictional pressure gradient density, said frictional pressure gradient density being proportional to the gel strength of said fluid.

Claim 23

A method of measuring the properties of a fluid comprising the steps of: (a) flowing a fluid through a substantially vertical conduit, (b) terminating said flow to retain a static column of fluid in said conduit, (c) measuring the pressure of said static column of fluid at vertically spaced points in said conduit, (d) determining the difference in pressure between said points to indicate the true density of said fluid, (e) restarting said flow of fluid and flowing said fluid at a flow rate where the shear rate of the flowing fluid is in the range of greater than zero to about 20 sec -1 , (f) measuring the pressure of said flowing fluid at said points, and (g) determining the difference in pressure between said points during flow to indicate an apparent density comprising the true density and a frictional pressure gradient density, said frictional pressure gradient density being proportional to the gel strength of said fluid.

Claim 24

A method of monitoring the gel strength of a drilling fluid: (a) generating a first signal proportional to the difference in static pressure of a liquid in a conduit at two vertically spaced points to indicate the true density of the liquid, (b) thereafter, generating a second signal proportion to the difference in pressure between said points during flow of the liquid through the conduit at a flow rate where the shear rate of the flowing liquid is in a range of greater than zero to about 20 sec -1 to thereby indicate an apparent density comprising the true density and a frictional pressure gradient density, and (c) comparing the first signal with the second signal to determine the difference therebetween, the difference being indicative of the gel strength of the drilling fluid.

Claim 25

A method of monitoring the gel strength of a drilling fluid: (a) generating a first signal proportional to the difference in static pressure of a liquid in a conduit at two vertically spaced points to indicate the true density of the liquid, (b) thereafter, generating a second signal proportion to the difference in pressure between said points during flow of the liquid through the conduit at a flow rate where the shear rate of the flowing liquid is in a range of greater than zero to about 20 sec -1 to thereby indicate an apparent density comprising the true density and a frictional pressure gradient density, and (c) comparing the first signal with the second signal to determine the difference therebetween, the difference being indicative of the gel strength of the drilling fluid.

Claim 26

An apparatus for measuring the density of a liquid which comprises: (a) a nonhorizontal conduit positioned to conduct liquid therethrough, (b) means for measuring the pressure differential between two vertically spaced locations in said conduit, (c) means for flowing liquid through said conduit, (d) means for cyclically interrupting flow of liquid through said conduit to provide a flow interval and a static interval, (e) means for measuring the differential pressure between said spaced locations during the static interval, and (f) means for maintaining a sufficient back pressure on said conduit to reduce substantially the effects of entrained gas in said liquid, said mean includes a valve connected to said conduit downstream of said differential pressure measuring means and including a housing and an elastomeric sleeve which in combination define a pressure chamber, and means for delivering a predetermined pressure to said chamber, said sleeve being inwardly deformable by pressure in said chamber to throttle flow therethrough to maintain said back pressure on said conduit.

Claim 27

An apparatus for measuring the density of a liquid which comprises: (a) a nonhorizontal conduit positioned to conduct liquid therethrough, (b) means for measuring the pressure differential between two vertically spaced locations in said conduit, (c) means for flowing liquid through said conduit, (d) means for cyclically interrupting flow of liquid through said conduit to provide a flow interval and a static interval, (e) means for measuring the differential pressure between said spaced locations during the static interval, and (f) means for maintaining a sufficient back pressure on said conduit to reduce substantially the effects of entrained gas in said liquid, said mean includes a valve connected to said conduit downstream of said differential pressure measuring means and including a housing and an elastomeric sleeve which in combination define a pressure chamber, and means for delivering a predetermined pressure to said chamber, said sleeve being inwardly deformable by pressure in said chamber to throttle flow therethrough to maintain said back pressure on said conduit.

Claim 29

An apparatus for measuring the density of a liquid which comprises: (a) a nonhorizontal conduit positioned to conduct liquid therethrough, (b) an outwardly flared inlet means disposed on the end of said conduit, said inlet means positioned in a generally vertical attitude and sized so that the vertical component of the liquid velocity in the area defined by the inlet means is less than the minimum liquid velocity through said apparatus. (c) means for measuring the pressure differential between two vertically spaced locations in said conduit. (d) means for flowing liquid through said conduit, (e) means for cyclically interrupting flow of liquid through said conduit to provide a flow interval and a static interval, and (f) means for measuring the differential pressure between said spaced locations during the static interval.

Claim 30

An apparatus for measuring the density of a liquid which comprises: (a) a nonhorizontal conduit positioned to conduct liquid therethrough, (b) an outwardly flared inlet means disposed on the end of said conduit, said inlet means positioned in a generally vertical attitude and sized so that the vertical component of the liquid velocity in the area defined by the inlet means is less than the minimum liquid velocity through said apparatus. (c) means for measuring the pressure differential between two vertically spaced locations in said conduit. (d) means for flowing liquid through said conduit, (e) means for cyclically interrupting flow of liquid through said conduit to provide a flow interval and a static interval, and (f) means for measuring the differential pressure between said spaced locations during the static interval.