Method of injecting fluids into underground formations

Claim 1

A method of injecting fluids into an underground formation penetrated by a wellbore, said method comprising: predetermining the hydrostatic pressure of a column of fluid having a height equal to the depth of the underground formation; providing a continuously partially pressure-balanced injection valve having a resultant differential pressure area responsive to the hydrostatic pressure of a colume of fluid thereabove to open said valve, and having an adjustable biasing means arranged to apply a closing force to said valve; adjusting said injection valve biasing means to a force exceeding the resultant differential pressure on said valve which would arise from said predetermined hydrostatic pressure; locating said injection valve in a tubing string in the under ground formation; placing in the tubing string treating fluid to be injected into the formation; filling any remaining portion of the tubing string with displacement fluid; and, applying fluid pressure to the tubing string to open said injection valve and inject said treating fluid into the formation.

Claim 2

A method of injecting fluids into an underground formation penetrated by a wellbore, said method comprising: predetermining the hydrostatic pressure of a column of fluid having a height equal to the depth of the underground formation; providing a continuously partially pressure-balanced injection valve having a resultant differential pressure area responsive to the hydrostatic pressure of a colume of fluid thereabove to open said valve, and having an adjustable biasing means arranged to apply a closing force to said valve; adjusting said injection valve biasing means to a force exceeding the resultant differential pressure on said valve which would arise from said predetermined hydrostatic pressure; locating said injection valve in a tubing string in the under ground formation; placing in the tubing string treating fluid to be injected into the formation; filling any remaining portion of the tubing string with displacement fluid; and, applying fluid pressure to the tubing string to open said injection valve and inject said treating fluid into the formation.

Claim 4

A method of injecting through a wellbore a precisely controlled amount of fluid into an underground formation having a formation pressure substantially less than the hydrostatic pressure of a full column of fluid in the wellbore above the formation; said method comprising: locating in the wellbore a tubing string having flow port means near the formation; placing in said tubing string near said formation and extending above the flow port means a valve member having a first pressure response area open to said tubing string, in valving relationship therein, and responsive to fluid pressure in the tubing string; simultaneously communicating said tubing string to a second, lesser pressure response area on the valve member opposing said first area; continuously and resiliently biasing said valve member towards a closed position in said tubing string with a biasing force exceeding the differential pressure force from a full column of fluid in the tubing above the valve member acting on the difference in area between said first and second pressure response areas; and, then pumping the desired injection volume of fluid into the full tubing with sufficient pressure to overcome said resilient biasing force and open said valve member.

Claim 5

A method of injecting through a wellbore a precisely controlled amount of fluid into an underground formation having a formation pressure substantially less than the hydrostatic pressure of a full column of fluid in the wellbore above the formation; said method comprising: locating in the wellbore a tubing string having flow port means near the formation; placing in said tubing string near said formation and extending above the flow port means a valve member having a first pressure response area open to said tubing string, in valving relationship therein, and responsive to fluid pressure in the tubing string; simultaneously communicating said tubing string to a second, lesser pressure response area on the valve member opposing said first area; continuously and resiliently biasing said valve member towards a closed position in said tubing string with a biasing force exceeding the differential pressure force from a full column of fluid in the tubing above the valve member acting on the difference in area between said first and second pressure response areas; and, then pumping the desired injection volume of fluid into the full tubing with sufficient pressure to overcome said resilient biasing force and open said valve member.

Claim 8

The method of treating through a conduit string in a wellbore an underground formation having a formation pressure below normal hydrostatic head at that depth; said method comprising: a. locating in a conduit string a partially and continuously pressure-balanced injection valve assembly; b. forming through the wall of said conduit string one or more flow ports communicating with said valve assembly; c. locating in said conduit string above said flow ports a packer assembly having first and second bypass valve means therein; d. lowering the conduit string into the wellbore with the first bypass valve means open to allow fluid to enter the string from the wellbore; e. placing the conduit so that the flow ports are in close proximity to the formation to be treated; f. closing the first bypass valve means and setting the packer in the casing to isolate the annulus below the packer; g. placing a predetermined amount of treating fluid into the conduit string on top of the existing fluid in the string; h. opening the second bypass valve means in the packer for allowing fluid to flow from the annulus below the packer to the annulus above the packer; i. filling the remainder of the conduit string with displacement fluid; j. calculating the amount of fluid existing in the conduit string below the treating fluid; k. pumping into the conduit string, under sufficient pressure to open said valve assembly, an amount of displacement fluid substantially equal to said calculated amount of existing fluid, thereby displacing said existing fluid up the annulus through said second bypass valve means; l. closing said second bypass valve means; and, m. pumping into the conduit string a volume of displacement fluid generally equivalent to said treating fluid volume, under sufficient pressure to open said valve assembly, thereby injecting said treating fluid into the desired formation.

Claim 9

The method of treating through a conduit string in a wellbore an underground formation having a formation pressure below normal hydrostatic head at that depth; said method comprising: a. locating in a conduit string a partially and continuously pressure-balanced injection valve assembly; b. forming through the wall of said conduit string one or more flow ports communicating with said valve assembly; c. locating in said conduit string above said flow ports a packer assembly having first and second bypass valve means therein; d. lowering the conduit string into the wellbore with the first bypass valve means open to allow fluid to enter the string from the wellbore; e. placing the conduit so that the flow ports are in close proximity to the formation to be treated; f. closing the first bypass valve means and setting the packer in the casing to isolate the annulus below the packer; g. placing a predetermined amount of treating fluid into the conduit string on top of the existing fluid in the string; h. opening the second bypass valve means in the packer for allowing fluid to flow from the annulus below the packer to the annulus above the packer; i. filling the remainder of the conduit string with displacement fluid; j. calculating the amount of fluid existing in the conduit string below the treating fluid; k. pumping into the conduit string, under sufficient pressure to open said valve assembly, an amount of displacement fluid substantially equal to said calculated amount of existing fluid, thereby displacing said existing fluid up the annulus through said second bypass valve means; l. closing said second bypass valve means; and, m. pumping into the conduit string a volume of displacement fluid generally equivalent to said treating fluid volume, under sufficient pressure to open said valve assembly, thereby injecting said treating fluid into the desired formation.