CA2449869A1 - Oil based drilling fluid - Google Patents
Oil based drilling fluid Download PDFInfo
- Publication number
- CA2449869A1 CA2449869A1 CA 2449869 CA2449869A CA2449869A1 CA 2449869 A1 CA2449869 A1 CA 2449869A1 CA 2449869 CA2449869 CA 2449869 CA 2449869 A CA2449869 A CA 2449869A CA 2449869 A1 CA2449869 A1 CA 2449869A1
- Authority
- CA
- Canada
- Prior art keywords
- drilling fluid
- oil
- base oil
- drilling
- sands
- 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.)
- Abandoned
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
- C09K8/02—Well-drilling compositions
- C09K8/32—Non-aqueous well-drilling compositions, e.g. oil-based
- C09K8/34—Organic liquids
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- Chemical & Material Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Lubricants (AREA)
Abstract
A method of forming bore holes in non-conventional hydrocarbon deposits, comprising the steps of circulating a drilling fluid through the bore hole during the drilling thereof, the drilling fluid being oil based.
Description
OIL BASED DRILLING FLUID
Field of the Invention The present invention relates to drilling fluids and more particularly to oil based drilling fluids used in the drilling of wells in nonconventional oil bearing formations.
Background of the Invention Large hydrocarbon reserves exist in the form of nonconventional deposits, particularly oil sands of the type found in the Fort McMurray arE:a of northern Alberta.
These deposits are non-conventional in the sense that, urslike conventional hydrocarbon deposits, the hydrocarbon exists in the form of a highly viscous bitumen that adheres to a particulate substrate, typically sand. As such, the bitumen will not flow to the well bore under formation pressure, nor can the bitumen be pumped from the well to the surface.
To date, the principle means of extraction has been to mine the oil sands, and to then treat the mined product to separate the bitumen from the substrate. The separation techniques are numerous and increasing.
Amongst operators in the oil sands, a methodology attracting more interest due to improved economics is referred to as steam assisted gravity drainage (SAGD).
This technique involves the drilling of large diameter (200-3'I 1 mm) horizontal holes through the oil sand formation to form producer well bores. Additional adjacent wells, which may also have diameters in the 311 mm range; are then drilled far the injection of steam.
The steam injection is required in order to allow the insitu bitumen to mobilize and be produced from the producer well. The produced bitumen is then refined to recover its usable hydrocarbon component.
A major problem when drilling into oil sands is the accretion of highly viscous and tacky bitumen onto the metal surfaces of the drilling tools and pipe, be it jointed pipe or coiled tubing. The bitumen accretion can become so severe 'that pipe and tools can become stuck in the well bore, preventing their extraction. The accretions result in additional operational challenges well known in the industry including plugging and increased energy consumption required to overcome the resistance of the bitumen against formation walls and other component and tool surfaces.
To date, the most prevalent method of preventing accretion has been to physically cool the drilling mud used when drilling the well bores. 'fhe cooled mud preserves the bitumen's inherent viscosity, which prevents it from mobilizing due to the frictional heat generated by drilling, and thereby limiting its accretion onto metal surfaces.
However, cooling of the drilling mud is far from completely effective, and adds considerably to drilling costs. Cooled drilling muds are themselves more viscous, increasing horsepower requirements for their circulation.
Another primary concern with SAGD is waste management. The muds used to drill the production and injection wells are water based which after use incorporate two liquid phases and a solids phase. The first liquid phase is of course the water which can be recycled but which must be significantly processed prior to recycling in order to remove drilled solids and liquid hydrocarbon contaminants. This is time consuming and costly.
Moreover, since water is required for steam injection, use of water in drilling muds reduces the supply available for steam generation. This is a not insignificant consideration in the Fort McMurray area where water deposits are limited.
Summay of the Invention It is an object of the present invention to provide a drilling mud which obviates and mitigates from the disadvantages of the prior art.
It is a further object of the present invention to provide an oil based drilling mud for use in the drilling of well bores in nonconventional oil sands deposits. Drilling with oil will _2_ reduce the waste stream to only solids and oil. By eliminating water, extra time normally required for separation of oil and drilled solids from water based fluids is not required when recycling the recoverable and reusable oil component of the drilling mud.
If the oil sands are drilled with an oil based mud, the problem of accretion and subsequent differential sticking can be reduced or perhaps even eliminated. The use of a low aromatic base oil such as a linear alpha olefin, because of the absence or near absence of aromatics, will help prevent dissolution of the bitumen being drilled to limit accretion.
If the bitumen is not being dissolved, an ancillary benefit should be greater bore hole integrity.
Detailed Description of the Preferred Embodiment The mud system proposed by the present invention consists of gelling a low aromatic hydrocarbon base oil with a phosphate esterlmetal complex. The pH of this system would be slightly acidic. This fluid would have the necessary rheological properties for drilling purposes. At the completion of drilling, after the production liner has been set, the system's viscosity can be broken by increasing the alkalinity of the fluid to raise its pH.
Suitable low or no aromatic base oils can include the following: AmodriIIT""
1410, Amodrill 1500 (linear alpha olefins), or Amodrill 2110 (poly alpha olefin) available from BP, Pure DriIIT"" HT-40N, HT-30N (paraffin base oils) or 1A-35 (paraffin base oil) available from PetroCanada, or Enviro-DriIITM, DriIIsoIT"" or LVT-200T'~. The base oils can be gelled with ChemoilT"' Gel or ChemoiITM Link, for example.
The gelled system will have a pH of about 4. If the pH is increased to about 5 or above, the micelles will begin to degrade and will be substantially or completely gone at a pH
of about 7.
Once the system's viscosity is broken, drilled solids can be rapidly separated from the oil based fluid by settling andlor centrifuging. Any bitumen that may have been incorporated into the drilling fluid can also be separated such as by centrifuging utilizing its higher specific gravity compared to the low aromatic base oil being used for the drilling fluid. The low aromatic hydrocarbon base oil can then be reused for drilling, the solids disposed of and any bitumen separated out can be directed to the refining facility to be blended with produced bitumen.
The present oil based fluid described above does not require oil wetfiing surfactants or emulsifiers of the sort normally used in oil based systems. As such, there is no concern with wettability alterations to the reservoir. A hydrocarbon based drilling fluid will also prevent the dispersion of clay minerals which could otherwise leach into the formation to diminish its permeability and impair production.
The above-described embodiments of the present invention are meant to be illustrative of preferred embodiments and are not intended to limit the scope of the present invention. Various modifications, which would be readily apparent to one skilled in the art, are intended to be within the scope of the present invention. The only limitations to the scope of the present invention are set forth in the following claims appended hereto.
Field of the Invention The present invention relates to drilling fluids and more particularly to oil based drilling fluids used in the drilling of wells in nonconventional oil bearing formations.
Background of the Invention Large hydrocarbon reserves exist in the form of nonconventional deposits, particularly oil sands of the type found in the Fort McMurray arE:a of northern Alberta.
These deposits are non-conventional in the sense that, urslike conventional hydrocarbon deposits, the hydrocarbon exists in the form of a highly viscous bitumen that adheres to a particulate substrate, typically sand. As such, the bitumen will not flow to the well bore under formation pressure, nor can the bitumen be pumped from the well to the surface.
To date, the principle means of extraction has been to mine the oil sands, and to then treat the mined product to separate the bitumen from the substrate. The separation techniques are numerous and increasing.
Amongst operators in the oil sands, a methodology attracting more interest due to improved economics is referred to as steam assisted gravity drainage (SAGD).
This technique involves the drilling of large diameter (200-3'I 1 mm) horizontal holes through the oil sand formation to form producer well bores. Additional adjacent wells, which may also have diameters in the 311 mm range; are then drilled far the injection of steam.
The steam injection is required in order to allow the insitu bitumen to mobilize and be produced from the producer well. The produced bitumen is then refined to recover its usable hydrocarbon component.
A major problem when drilling into oil sands is the accretion of highly viscous and tacky bitumen onto the metal surfaces of the drilling tools and pipe, be it jointed pipe or coiled tubing. The bitumen accretion can become so severe 'that pipe and tools can become stuck in the well bore, preventing their extraction. The accretions result in additional operational challenges well known in the industry including plugging and increased energy consumption required to overcome the resistance of the bitumen against formation walls and other component and tool surfaces.
To date, the most prevalent method of preventing accretion has been to physically cool the drilling mud used when drilling the well bores. 'fhe cooled mud preserves the bitumen's inherent viscosity, which prevents it from mobilizing due to the frictional heat generated by drilling, and thereby limiting its accretion onto metal surfaces.
However, cooling of the drilling mud is far from completely effective, and adds considerably to drilling costs. Cooled drilling muds are themselves more viscous, increasing horsepower requirements for their circulation.
Another primary concern with SAGD is waste management. The muds used to drill the production and injection wells are water based which after use incorporate two liquid phases and a solids phase. The first liquid phase is of course the water which can be recycled but which must be significantly processed prior to recycling in order to remove drilled solids and liquid hydrocarbon contaminants. This is time consuming and costly.
Moreover, since water is required for steam injection, use of water in drilling muds reduces the supply available for steam generation. This is a not insignificant consideration in the Fort McMurray area where water deposits are limited.
Summay of the Invention It is an object of the present invention to provide a drilling mud which obviates and mitigates from the disadvantages of the prior art.
It is a further object of the present invention to provide an oil based drilling mud for use in the drilling of well bores in nonconventional oil sands deposits. Drilling with oil will _2_ reduce the waste stream to only solids and oil. By eliminating water, extra time normally required for separation of oil and drilled solids from water based fluids is not required when recycling the recoverable and reusable oil component of the drilling mud.
If the oil sands are drilled with an oil based mud, the problem of accretion and subsequent differential sticking can be reduced or perhaps even eliminated. The use of a low aromatic base oil such as a linear alpha olefin, because of the absence or near absence of aromatics, will help prevent dissolution of the bitumen being drilled to limit accretion.
If the bitumen is not being dissolved, an ancillary benefit should be greater bore hole integrity.
Detailed Description of the Preferred Embodiment The mud system proposed by the present invention consists of gelling a low aromatic hydrocarbon base oil with a phosphate esterlmetal complex. The pH of this system would be slightly acidic. This fluid would have the necessary rheological properties for drilling purposes. At the completion of drilling, after the production liner has been set, the system's viscosity can be broken by increasing the alkalinity of the fluid to raise its pH.
Suitable low or no aromatic base oils can include the following: AmodriIIT""
1410, Amodrill 1500 (linear alpha olefins), or Amodrill 2110 (poly alpha olefin) available from BP, Pure DriIIT"" HT-40N, HT-30N (paraffin base oils) or 1A-35 (paraffin base oil) available from PetroCanada, or Enviro-DriIITM, DriIIsoIT"" or LVT-200T'~. The base oils can be gelled with ChemoilT"' Gel or ChemoiITM Link, for example.
The gelled system will have a pH of about 4. If the pH is increased to about 5 or above, the micelles will begin to degrade and will be substantially or completely gone at a pH
of about 7.
Once the system's viscosity is broken, drilled solids can be rapidly separated from the oil based fluid by settling andlor centrifuging. Any bitumen that may have been incorporated into the drilling fluid can also be separated such as by centrifuging utilizing its higher specific gravity compared to the low aromatic base oil being used for the drilling fluid. The low aromatic hydrocarbon base oil can then be reused for drilling, the solids disposed of and any bitumen separated out can be directed to the refining facility to be blended with produced bitumen.
The present oil based fluid described above does not require oil wetfiing surfactants or emulsifiers of the sort normally used in oil based systems. As such, there is no concern with wettability alterations to the reservoir. A hydrocarbon based drilling fluid will also prevent the dispersion of clay minerals which could otherwise leach into the formation to diminish its permeability and impair production.
The above-described embodiments of the present invention are meant to be illustrative of preferred embodiments and are not intended to limit the scope of the present invention. Various modifications, which would be readily apparent to one skilled in the art, are intended to be within the scope of the present invention. The only limitations to the scope of the present invention are set forth in the following claims appended hereto.
Claims (23)
1. A method of forming bore holes in non-conventional hydrocarbon deposits, comprising the steps of:
circulating a drilling fluid through said bore hole during the drilling thereof, said drilling fluid being oil based.
circulating a drilling fluid through said bore hole during the drilling thereof, said drilling fluid being oil based.
2. The method of claim 1 wherein said oil based drilling fluid comprises a base oil with low or no aromatics therein.
3. The method of claim 2 wherein said base oil is a linear alpha olefin.
4. The method of claim 2 wherein said base oil is a poly alpha olefin.
5. The method of claim 2 wherein said base oil is a paraffin based oil.
6. The method of any of claims 2 to 5 wherein said base oil is gelled with a phosphate ester/metal complex.
7. The method of claim 6 wherein said phosphate ester/metal complex is Chemoil Gel or Chemoil Link.
8. The method of claim 6 wherein said base oil is gelled at a pH of about 4.
9. The method of claim 8 wherein said gelled base oil can be broken by increasing the alkalinity thereof.
10. The method of claims 8 or 9 wherein said gelled base oil can be broken by increasing its pH above 5.
11. The method of any of claims 1 to 10 wherein said non-conventional hydrocarbon deposits are oil sands.
12. A drilling fluid for use in the drilling of bore holes in non-conventional hydrocarbon deposits, the drilling fluid comprising a base oil and a viscosifying agent for said base oil.
13. The drilling fluid of claim 12 wherein said base oil has a low or no concentration of aromatics therein.
14. The drilling fluid of claim 13 wherein said base oil is a linear alpha olefin.
15. The drilling fluid of claim 13 wherein said base oil is a poly alpha olefin.
16. The drilling fluid of claim 13 wherein said base oil is a paraffin based oil.
17. The drilling fluid of any of claims 12 to 16 wherein said viscosifying agent is a phosphate ester/metal complex.
18. The drilling fluid of claim 17 wherein said phosphate ester/metal complex is Chemoil Gel or Chemoil Link.
19. The drilling fluid of any of claims 12 to 18 wherein said base oil is viscosified at a pH of about 4.
20. The drilling fluid of claim 19 wherein the viscosity of said base oil can be broken by increasing the pH thereof.
21. The drilling fluid of claim 20 wherein the viscosity of said base oil can be broken by increasing its pH to about 5 or greater.
22. The drilling fluid of any of claims 12 to 21 wherein said non-conventional hydrocarbon deposits are oil sands.
23. A method of inhibiting the accretion of bitumen on metal surfaces during the drilling of oil sands comprising the steps of:
viscosifying an oil based drilling fluid; and circulating said oil based drilling fluid while drilling through said oil sands, said oil based drilling fluid having a sufficiently low aromatic content that bitumen in said oil sands is not dissolved during drilling.
viscosifying an oil based drilling fluid; and circulating said oil based drilling fluid while drilling through said oil sands, said oil based drilling fluid having a sufficiently low aromatic content that bitumen in said oil sands is not dissolved during drilling.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2449869 CA2449869A1 (en) | 2003-11-18 | 2003-11-18 | Oil based drilling fluid |
| CA002478622A CA2478622A1 (en) | 2003-11-18 | 2004-08-20 | Oil based drilling fluid |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2449869 CA2449869A1 (en) | 2003-11-18 | 2003-11-18 | Oil based drilling fluid |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2449869A1 true CA2449869A1 (en) | 2005-05-18 |
Family
ID=34558370
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2449869 Abandoned CA2449869A1 (en) | 2003-11-18 | 2003-11-18 | Oil based drilling fluid |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2449869A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US11319474B2 (en) | 2017-02-03 | 2022-05-03 | Saudi Arabian Oil Company | Oil-based fluid compositions for hydrocarbon recovery applications |
-
2003
- 2003-11-18 CA CA 2449869 patent/CA2449869A1/en not_active Abandoned
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US11319474B2 (en) | 2017-02-03 | 2022-05-03 | Saudi Arabian Oil Company | Oil-based fluid compositions for hydrocarbon recovery applications |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Dead |