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GB1582241A - Measuring earth fracture pressures - Google Patents

Measuring earth fracture pressures Download PDF

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Publication number
GB1582241A
GB1582241A GB2064076A GB2064076A GB1582241A GB 1582241 A GB1582241 A GB 1582241A GB 2064076 A GB2064076 A GB 2064076A GB 2064076 A GB2064076 A GB 2064076A GB 1582241 A GB1582241 A GB 1582241A
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GB
United Kingdom
Prior art keywords
formation
borehole
liquid
pressure
housing
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
GB2064076A
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BP PLC
Original Assignee
BP PLC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by BP PLC filed Critical BP PLC
Priority to GB2064076A priority Critical patent/GB1582241A/en
Publication of GB1582241A publication Critical patent/GB1582241A/en
Expired legal-status Critical Current

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Classifications

    • EFIXED CONSTRUCTIONS
    • E21EARTH OR ROCK DRILLING; MINING
    • E21BEARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B49/00Testing the nature of borehole walls; Formation testing; Methods or apparatus for obtaining samples of soil or well fluids, specially adapted to earth drilling or wells
    • E21B49/006Measuring wall stresses in the borehole
    • EFIXED CONSTRUCTIONS
    • E21EARTH OR ROCK DRILLING; MINING
    • E21BEARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B47/00Survey of boreholes or wells
    • E21B47/06Measuring temperature or pressure
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/24Earth materials

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  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Geology (AREA)
  • Mining & Mineral Resources (AREA)
  • Physics & Mathematics (AREA)
  • Environmental & Geological Engineering (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Fluid Mechanics (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Remote Sensing (AREA)
  • Geophysics (AREA)
  • Food Science & Technology (AREA)
  • Medicinal Chemistry (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Investigation Of Foundation Soil And Reinforcement Of Foundation Soil By Compacting Or Drainage (AREA)
  • Measuring Fluid Pressure (AREA)

Description

(54) MEASURING EARTH FRACTURE PRESSURES (71) We, THE BRITISH PETROLEUM COMPANY LIMITED, of Britannic House, Moor Lane, London, EC2Y 9BU, a British Company, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement:- This invention relates to a method of determining the fracture pressure of a subterranean formation at the bottom of a borehole and also to an apparatus therefor.
It is conventional practice in oil well drilling to pump drilling mud down the interior of the drill string to the drill bit at the bottom of the borehole where.the mud mixes with the drill cuttings and the mixture thereby produced flows back to the surface through the annulus between the drill string and casing. The mixture of mud and cuttings in the annulus can, depending on the length of the annulus, cause a large hydrostatic pressure to be exerted on the formation at the bottom of the borehole, and sometimes this hydrostatic pressure can be such that there is a risk of the mixture and/or drilling mud escaping into the formation.
It is accordingly useful for the drilling or petroleum engineer to know the fracture pressure of the formation at the bottom of the borehole so that steps may be taken to eliminate or reduce the risk of loss of drilling fluid with the consequent danger to the formation.
The term fracture pressure is well known to drilling and petroleum engineers.
It is an object of the present invention to provide a method and apparatus of measuring the fracture pressure of a formation at the bottom of a borehole.
According to the present invention a method of measuring the fracture pressure of a formation at the bottom of a borehole comprises supplying liquid under pressure to the bottom of the borehole to carlse the liquid to flow into the formation, measuring the rate of flow of liquid into the formation and measuring the pressure in.the liquid entering the formation or a parameter indicative thereof, and measuring the rates of flow at different pressures and recording the pressure at which there is a sharp increase in the flow rate.
From the flow rate the permeability can be calculated. The pressure at which there is a sharp increase in flow rate is the fracture pressun of the formation.
Preferably the method comprises penetrating the formation at the bottom of the borehole by means of a porous member whose permeability to water is higher than that of the formation at the bottom of the borehole and supplying water under pressure to the porous member so that the water is caused to enter the formation.
According to another aspect of the present invention an apparatus for measuring the fracture pressure of a subterranean formation at the bottom of a borehole the apparatus being suitable for insertion through a drill string into the borehole to penetrate the formation at the bottom of the borehole, comprises a porous member located at the lower end thereof for penetrating the formation at the bottom of the borehole and means for supplying liquid under pressure to the porous member to cause the liquid to flow through the porous member to enter the formation.and means for measuring the pressure in the liquid entering the formation and relaying the measurements to the surface.
The apparatus can comprise a housing having at its lower end the porous member for penetrating the formation, the housing enclosing a conduit arranged to deliver liquid to the porous member. The liquid can conveniently be water.
The means for measuring the pressure in the liquid entering the formation can be a transducer having an electric cable for relaying the measurements to the surface.
The transducer can be in the region of the porous member.
Preferably the apparatus has a flowmeter for measuring the rate of flow of liquid through the pipe into the formation.
Conveniently the flow meter is located at or near the bottom of the hole.
The housing can enclose the electric cable.
Preferably the porous member is a stone of the type used in oil field permeability measurements to assist the dispersing the fluid uniformly and to prevent blocking of the lower end of the pipe. Such porous stones are available commer cially.
Preferably the housing has a means to prevent the liquid supplied to the formation flowing up the side of the housing and into the borehole. The means can conveniently be an inflatable well packer attached to the exterior of the housing.
Preferably the apparatus has means for latching with the drill string near the bit.
The invention is illustrated with reference to the accompanying drawing in which Figure 1 is a part vertical section part elevation of the apparatus having penetrated the formation at the bottom of a borehole. The apparatus is shown extending below an open centre bit 3 connected to a drill string 5. Figure 2 is a vertical section of a modified form of a probe on a larger scale.
The apparatus which is indicated generally by reference numeral 2 comprises a means for .penetrating the formation and supplying liquid under pressure to the bottom of the borehole in the form of probe 1 enclosing a pipe 4, and means for measuring the pressure in the form of a transducer 6 located at the end of cable 8 which passes information from the transducer 6 to the surface. The pipe 4 has its lower end buried in a porous stone 10 for dispersing the water and preventing clogging of the pipe 4, the stone 10 having been selected so that its permeability to water is significantly higher than that of the soil at the bottom 9 of the borehole 7.
The pipe 4 and cable 8 are enclosed by a tubular housing 12 the end of which also holds the porous stone 10. The tubular housing 12 has a packer 14 attached thereto to prevent water flowing upward into the borehole above the packer. The tubular housing 12 is supported on a wire line from the surface (not shown) and by latching to the drill string 5 near the bit 3.
With reference to Figure 2 the assembly of stone 10 and brass head 20 is available commercially as a unit. The housing 12 is connected to the head 20 by screw thread or other means (not shown) and the pipe 4 to the opening 24 in the head 20 also by a screw thread (not shown).
In the stone 10 is a cavity 22 containing a transducer 6.
In operation the borehole 7 is drilled to the depth at which it is desired to measure the fracture pressure of the formation. The drill string is then retracted 3 to 4 metres and the apparatus lowered so that is latches into the drill string with the stone 10 protruding about 2 metres below the drill bit.
The drill string 5 is then lowered so that its weight pushes the stone 10 about 2 metres into the formation at the bottom 9 of the borehole 7. The packer 14 is then inflated. Water is then pumped down the pipe 4 into the recess 22 in the stone 10 and the flow rate of the water into the formation measured and from this is calculated the permeability. By means of the transducer 6 the pressure is also measured and the permeability measured at different pressures until there is a sudden increase in permeability at the fracture pressure of the formation.
The method of the invention is particularly suitable for use in a site evaluation programme, which is usually prior to an oil well drilling programme.
WHAT WE CLAIM IS: 1. An apparatus suitable for measuring the fracture pressure of a subterranean formation at the bottom of a borehole the apparatus being suitable for insertion through a drill string into the borehole to penetrate the formation at the bottom of the borehole, the apparatus comprising a porous member located at the lower end thereof for penetrating the formation at the bottom of the borehole and means for supplying liquid under pressure to the porous member to cause the liquid to flow through the porous member to enter the formation and means for measuring the pressure in the liquid entering the formation and relaying the measurements to the surface.
2. An apparatus as claimed in Claim 1 wherein the apparatus comprises a housing having at its lower end the porous member for penetrating the formation, the housing enclosing a conduit for the liquid which conduit is arranged to deliver liquid to the porous member.
3. An apparatus as claimed in Claim 2 wherein the porous member is a stone of the type used in oil field permeability measurements 4. An apparatus as claimed in Claim 2 or 3 wherein the housing has means to prevent the liquid supplied to the formation flowing up the side of the housing into the borehole.
5. An apparatus as claimed in any one of Claims 1 to 4 having means for latching with the drill string in the region ofthe bit.
6. An apparatus as claimed in any one of Claims l to 5 comprising a wire line for supporting the apparatus in the borehole from the surface.
7. An apparatus as claimed in any one of Claims 2 to 6 wherein the means for measuring the pressure in the liquid entering the formation comprises a transducer located in the region of the porous member.
8. A method of measuring the fracture pressure of a formation at the bottom of a borehole which method comprises supplying liquid under pressure to the bottom of the borehole to cause the liquid to flow into the formation, measuring the rate of flow of liquid into the formation and measuring the pressure in the liquid entering the formation or a parameter indicative thereof, and measuring the rates of flow at different pressures and recording the pressure at which there is a sharp increase in the flow rate.
9. A method as claimed in Claim 8 which method comprises penetrating the formation at the bottom of the borehole; and supplying the liquid to and causing same go enter the
**WARNING** end of DESC field may overlap start of CLMS **.

Claims (11)

**WARNING** start of CLMS field may overlap end of DESC **. pipe. Such porous stones are available commer cially. Preferably the housing has a means to prevent the liquid supplied to the formation flowing up the side of the housing and into the borehole. The means can conveniently be an inflatable well packer attached to the exterior of the housing. Preferably the apparatus has means for latching with the drill string near the bit. The invention is illustrated with reference to the accompanying drawing in which Figure 1 is a part vertical section part elevation of the apparatus having penetrated the formation at the bottom of a borehole. The apparatus is shown extending below an open centre bit 3 connected to a drill string 5. Figure 2 is a vertical section of a modified form of a probe on a larger scale. The apparatus which is indicated generally by reference numeral 2 comprises a means for .penetrating the formation and supplying liquid under pressure to the bottom of the borehole in the form of probe 1 enclosing a pipe 4, and means for measuring the pressure in the form of a transducer 6 located at the end of cable 8 which passes information from the transducer 6 to the surface. The pipe 4 has its lower end buried in a porous stone 10 for dispersing the water and preventing clogging of the pipe 4, the stone 10 having been selected so that its permeability to water is significantly higher than that of the soil at the bottom 9 of the borehole 7. The pipe 4 and cable 8 are enclosed by a tubular housing 12 the end of which also holds the porous stone 10. The tubular housing 12 has a packer 14 attached thereto to prevent water flowing upward into the borehole above the packer. The tubular housing 12 is supported on a wire line from the surface (not shown) and by latching to the drill string 5 near the bit 3. With reference to Figure 2 the assembly of stone 10 and brass head 20 is available commercially as a unit. The housing 12 is connected to the head 20 by screw thread or other means (not shown) and the pipe 4 to the opening 24 in the head 20 also by a screw thread (not shown). In the stone 10 is a cavity 22 containing a transducer 6. In operation the borehole 7 is drilled to the depth at which it is desired to measure the fracture pressure of the formation. The drill string is then retracted 3 to 4 metres and the apparatus lowered so that is latches into the drill string with the stone 10 protruding about 2 metres below the drill bit. The drill string 5 is then lowered so that its weight pushes the stone 10 about 2 metres into the formation at the bottom 9 of the borehole 7. The packer 14 is then inflated. Water is then pumped down the pipe 4 into the recess 22 in the stone 10 and the flow rate of the water into the formation measured and from this is calculated the permeability. By means of the transducer 6 the pressure is also measured and the permeability measured at different pressures until there is a sudden increase in permeability at the fracture pressure of the formation. The method of the invention is particularly suitable for use in a site evaluation programme, which is usually prior to an oil well drilling programme. WHAT WE CLAIM IS:
1. An apparatus suitable for measuring the fracture pressure of a subterranean formation at the bottom of a borehole the apparatus being suitable for insertion through a drill string into the borehole to penetrate the formation at the bottom of the borehole, the apparatus comprising a porous member located at the lower end thereof for penetrating the formation at the bottom of the borehole and means for supplying liquid under pressure to the porous member to cause the liquid to flow through the porous member to enter the formation and means for measuring the pressure in the liquid entering the formation and relaying the measurements to the surface.
2. An apparatus as claimed in Claim 1 wherein the apparatus comprises a housing having at its lower end the porous member for penetrating the formation, the housing enclosing a conduit for the liquid which conduit is arranged to deliver liquid to the porous member.
3. An apparatus as claimed in Claim 2 wherein the porous member is a stone of the type used in oil field permeability measurements
4. An apparatus as claimed in Claim 2 or 3 wherein the housing has means to prevent the liquid supplied to the formation flowing up the side of the housing into the borehole.
5. An apparatus as claimed in any one of Claims 1 to 4 having means for latching with the drill string in the region ofthe bit.
6. An apparatus as claimed in any one of Claims l to 5 comprising a wire line for supporting the apparatus in the borehole from the surface.
7. An apparatus as claimed in any one of Claims 2 to 6 wherein the means for measuring the pressure in the liquid entering the formation comprises a transducer located in the region of the porous member.
8. A method of measuring the fracture pressure of a formation at the bottom of a borehole which method comprises supplying liquid under pressure to the bottom of the borehole to cause the liquid to flow into the formation, measuring the rate of flow of liquid into the formation and measuring the pressure in the liquid entering the formation or a parameter indicative thereof, and measuring the rates of flow at different pressures and recording the pressure at which there is a sharp increase in the flow rate.
9. A method as claimed in Claim 8 which method comprises penetrating the formation at the bottom of the borehole; and supplying the liquid to and causing same go enter the
penetrated formation.
10. A method as claimed in Claim 9 which comprises penetrating the formation at the bottom of the borehole by means of a porous member whose permeability to water is higher than that of the formation at the bottom of the borehole and supplying water under pressure to the porous member so that the water is caused to enter the formation.
11. An apparatus substantially as hereinbefore described with reference to Figures 1 and 2 of the accompanying drawings.
GB2064076A 1977-04-27 1977-04-27 Measuring earth fracture pressures Expired GB1582241A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB2064076A GB1582241A (en) 1977-04-27 1977-04-27 Measuring earth fracture pressures

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB2064076A GB1582241A (en) 1977-04-27 1977-04-27 Measuring earth fracture pressures

Publications (1)

Publication Number Publication Date
GB1582241A true GB1582241A (en) 1981-01-07

Family

ID=10149264

Family Applications (1)

Application Number Title Priority Date Filing Date
GB2064076A Expired GB1582241A (en) 1977-04-27 1977-04-27 Measuring earth fracture pressures

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GB (1) GB1582241A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1997037103A1 (en) * 1996-03-28 1997-10-09 Shell Internationale Research Maatschappij B.V. Method and system for monitoring a characteristic of an earth formation in a well

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1997037103A1 (en) * 1996-03-28 1997-10-09 Shell Internationale Research Maatschappij B.V. Method and system for monitoring a characteristic of an earth formation in a well
RU2169838C2 (en) * 1996-03-28 2001-06-27 Шелл Интернэшнл Рисерч Маатсхаппий Б.В. System testing borehole
CN1079888C (en) * 1996-03-28 2002-02-27 国际壳牌研究有限公司 Method and sytsem for monitoring characteristic of earth formation in well

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PS Patent sealed
PCNP Patent ceased through non-payment of renewal fee