IN-SITU FLUID COMPATIBILITY TESTING USING A WIRELINE FORMATION TESTER

• US 20100242586A1
• Filed: 11/17/2008
• Published: 09/30/2010
• Est. Priority Date: 11/19/2007
• Status: Active Grant

• Current Assignee: Shell Oil Company (Shell Plc)
• Original Assignee: Shell Oil Company (Shell Plc)
• Inventors: Elshahawi, Hani, Hashem, Mohamed Naguib
• Granted Patent: US 8,418,546 B2
• Time in Patent Office: Days
• US Class Current: 73/152.390
• CPC Class Codes: E21B 33/1243 with inflatable sleeves
• CPC Class Codes: E21B 49/082 Wire-line fluid samplers E21B49/083 takes precedence

Abstract

A method for performing fluid influx tests in a wellbore (3) traversing a permeable formation (4) to test the compatibility of one or more completion fluids comprises: a) inserting a well test device (1) comprising a straddle packer assembly (6A,6B) into the wellbore (3) such that the straddle packer assembly (6A,6B) separates a well test section (13) from other sections of the wellbore; b) performing a first fluid influx test during which the fluid pressure the test section (13) is reduced, pore fluid is induced to flow from the pores of the permeable formation (4) into the test section (13) and fluid influx into the test section (13) is monitored; c) injecting a completion fluid into the test section (13), thereby increasing the fluid pressure within the test section and inducing the completion fluid to flow into the pores of the surrounding formation (4); d) performing a second fluid influx test during which the fluid pressure within the test section (13) is reduced, the completion fluid and pore fluid are induced to flow into the test section, and fluid influx into the test section is monitored; e) comparing fluid influx monitoring data acquired during the first and second fluid influx tests according to step b) and d) to determine any effects of the completion fluid on the influx of formation pore fluid into the test section.

Claims

1. A method for performing fluid influx tests in a wellbore traversing a permeable formation, comprising:

a) inserting a well test device comprising a straddle packer assembly into the wellbore such that the straddle packer assembly separates a test section from other sections of the wellbore;

b) performing a first fluid influx test during which the fluid pressure the test section is reduced, pore fluid is induced to flow from the pores of the permeable formation into the test section and fluid influx into the test section is monitored;

c) injecting a first completion fluid into the test section, thereby increasing the fluid pressure within the test section and inducing the completion fluid to flow into the pores of the surrounding formation;

d) performing a second fluid influx test during which the fluid pressure within the test section is reduced, the first completion fluid and pore fluid are induced to flow into the test section, and fluid influx into the test section is monitored;

e) comparing fluid influx monitoring data acquired during the first and second fluid influx tests according to step b) and d) to determine any effects of the first completion fluid on the influx of formation pore fluid into the test section.

2. The method of claim 1, wherein the method further comprises:

f) injecting a second completion fluid into the test section, thereby increasing the fluid pressure within the test section and inducing the second completion fluid to flow into the surrounding formation;

g) performing a third production test during which the fluid pressure within the test section is reduced, completion fluid and pore fluid are induced to flow into the test section, and fluid influx into the test section is monitored;

h) comparing fluid influx monitoring data acquired during the first, second and third fluid influx tests according to steps b),d) and g) to determine any effects of the injected first and second completion fluids on the fluid influx into the test section;

i) selecting from the comparison according to step h) the most suitable completion fluid; and

j) injecting during subsequent well completion operations the selected most suitable completion fluid into the permeable formation surrounding the wellbore.

3. The method of claim 2, wherein the method further comprises:

k) injecting an n-th completion fluid, wherein n is an integer and at least 4, into the test section, thereby increasing the fluid pressure within the test section and inducing the n-th completion fluid to flow into the surrounding formation;

l) performing a (n-1)th fluid influx test during which the fluid pressure within the test section is reduced, the n-th completion fluid and pore fluid are induced to flow into the test section, and fluid influx into the test section is monitored;

m) comparing fluid influx monitoring data acquired during the first, second, third, and (n−

1)th fluid influx tests according to steps b), d), g) and l) to determine any effects of the injected first, second, third and n-th completion fluids on the fluid influx into the well;

n) selecting from the comparison according to step m) the most suitable completion fluid; and

o) injecting during subsequent well completion operations the most suitable completion fluid selected in accordance with step m) into the pores of the formation.

4. The method of claim 1 wherein the during each of the fluid influx tests the wellbore is substantially filled with a drilling fluid and the pressure in the test section is reduced to a selected value by a pump which pumps fluid from the test section into an adjacent wellbore section, and the pressure within the test section, the fluid influx velocity and/or the composition of the fluid flowing from the formation into the test section are monitored.

5. The method of claim 4, wherein the composition of the produced fluid flowing from the formation into the test section during each of the fluid influx tests is monitored by pumping a sample of produced fluid into a sampling container, which is connected to the well test device.

6. The method of claim 1 wherein the first second, third and n-th completion fluids are stored in completion fluid storage containers which are connected to the well test device.

7. The method of claim 1 wherein the well test device tool is suspended from a wireline in the wellbore of an exploration well.

8. The method of claim 1 wherein the well test device is maintained within the same section of the wellbore during each of the fluid influx tests.

9. The method of claim 1 wherein the formation testing tool is moved in longitudinal direction through the wellbore between the second, third, and n-th production tests to another section of the wellbore that traverses the permeable formation, which other section is not invaded by the completion fluid injected during a preceding well influx test.

10. The method of claim 1 wherein the method is used to test the performance of a stimulation fluid that is configured to enhance production of hydrocarbon fluid from the formation.

11. The method of claim 1 wherein the method is used to test the performance of a sealing fluid, that is configured to seal off a thief zone to inhibit influx of an aqueous or another undesired fluid into a hydrocarbon production well.

12. The method of claim 1 wherein the method is used to determine any reactivity between the injected first and/or any further completion fluid and rock material of and/or pore fluid within the permeable formation and/or modification of the wettability of the rock material and/or reduction or other modification of the viscosity of the pore fluid by any solvents in the first and/or any further completion fluid and/or by any difference between the temperature of the first and/or further completion fluid and the pore fluid.

13. The method of claim 1 wherein the permeable formation contains pore fluid comprising crude oil and/or natural gas and wherein after performing fluid influx tests in accordance with any preceding claim at least one tested completion fluid is injected into the wellbore and pore fluid comprising crude oil and/or natural gas is produced through the wellbore.

14. A well test device for use in the production testing method of claim 1 comprising:

a straddle packer assembly;

a pump for reducing the fluid pressure in a test section formed in use between the packers of the straddle packer assembly and a section of a hydrocarbon containing formation traversed by a wellbore in which the production testing tool is suspended;

means for injecting a completion fluid into the test section; and

means for monitoring fluid influx into the test section during each fluid influx test.

15. The well test device of claim 14, wherein the means for injecting a completion fluid into the test section comprises a container for storing a completion fluid and a pump for injecting the completion fluid via the test section into the formation during a production test.

16. The well test device of claim 15, wherein the means for injecting a completion fluid into the test section comprises a plurality of containers in which different completion fluids are stored, such that different completion fluids can be injected into the formation to carry out a sequence of production tests in which the effects of each completion fluid on fluid influx is assessed.