DRILLING COMPOSITION, PROCESS FOR ITS PREPARATION, AND APPLICATIONS THEREOF

Abstract

The present invention relates to a drilling composition comprising an organic phase having at least one linear or branched, cyclic or non-cyclic, saturated hydrocarbon, at least one ester, water or aqueous phase, and at least one additive.

The present invention additionally relates to the use and preparation of the drilling composition, to a drilling system, to a process for making a borehole, to a process for conveying cuttings, to a process for treating a drill head, and to a process for production of oil and/or gas.

Claims

1. A drilling composition comprising I) an organic phase comprising components i. from about 20 wt. % to about 99.999 wt. %, based on the total weight of components i. and ii., of at least one linear or branched, cyclic or non-cyclic, saturated hydrocarbon, ii. from about 0.001 wt. % to about 25 wt. %, based on the total weight of components i. and ii., of at least one ester, II) from 0 to about 50 wt. %, based on the total weight of the composition, of water or aqueous phase, and III) from 0 to about 60 wt. %, based on the total weight of the composition, of at least one additive, wherein the sum of the weight components I) to III) is 100 wt. %.

2. The drilling composition according to claim 1, wherein the at least one hydrocarbon is at least one alkane.

3. The drilling composition according to claim 1, wherein the at least one ester is at least one ester selected from the group consisting of esters formed from at least one C.sub.1 to C.sub.24 monocarboxylic acid with at least one mono-functional alcohol.

4. The drilling composition according to claim 1, wherein the composition is in the form of an emulsion.

5. The drilling composition according to claim 1, wherein the at least one additive is at least one additive selected from the group consisting of weighting agents, clays, fluid loss additives, pH modifiers, viscosity modifiers, filtration control agents, emulsifiers, salts, wetting agents, dispersants.

6. The drilling composition according to claim 1, wherein the at least one ester has a carbon chain distribution of an acid-derived component with carbon numbers in the ranges of from 0 to 0.50% C.sub.6, from 4.00% to 7.00% C.sub.8, from 5.00% to 8.00% C.sub.10, from 60.00% to 80.00% C.sub.12, from 10.00 to 20.00% C.sub.14, from 2.00 to 4.00% C.sub.16 and from 0.1 to 0.60% C.sub.18.

7. The drilling composition according to claim 1, wherein the at least one ester has a carbon chain distribution of the acid-derived component with carbon numbers in the ranges of from 0 to 2.00% C.sub.6, from 0 to 10.00% C.sub.8, from 0 to 10.00% C.sub.10, from 0 to 5.00% C.sub.16 and from 0 to 1.00% C.sub.18.

8. A process for the preparation of a drilling composition, comprising the steps: a) providing as component i. from about 20 wt. % to about 99.999 wt. %, based on the total amount of i. and ii., of at least one linear or branched, cyclic or non-cyclic, saturated hydrocarbon, b) providing as component ii. from about 0.001 wt. % to about 25 wt. %, based on the total amount of i. and ii., of at least one ester having a carbon chain distribution of an acid-derived component with carbon numbers in the ranges of from 0 to 2.00% C.sub.6, from 3.00% to 10.00% C.sub.8, from 3.00% to 10.00% C.sub.10, from 50.00% to 94.00% C.sub.12, from 0 to 25.00% C.sub.14, from 0 to 5.00% C.sub.16 and from 0 to 1.00% C.sub.18, and wherein the sum of the weight amounts provided in a) and b) is 100 wt. %, c) combining the at least one hydrocarbon and the at least one ester.

9. A process for preparation of a drilling composition, comprising the steps: A) preparing an organic phase comprising components i. from about 20 wt. % to about 99.999 wt. %, based on the total weight of components i. and ii., of at least one linear or branched, cyclic or non-cyclic, saturated hydrocarbon, ii. from about 0.001 wt. % to about 25 wt. %, based on the total weight of components i. and ii., of at least one ester having a carbon chain distribution of an acid-derived component with carbon numbers in the ranges of from 0 to 2.00% C.sub.6, from 3.00% to 10.00% C.sub.8, from 3.00% to 10.00% C.sub.10, from 50.00% to 94.00% C.sub.12, from 0 to 25.00% C.sub.14, from 0 to 5.00% C.sub.16 and from 0 to 1.00% C.sub.18, B) preparing an aqueous phase comprising from about 50 wt. % to 100 wt. % water, based on the total amount of aqueous phase, C) combining the organic phase prepared in step A) with from 0 to 50 wt. %, based on the total weight of the composition, of the aqueous phase prepared in step B), and D) combining at least one of the organic phase, the aqueous phase and the combination of the organic phase and the aqueous phase with from 0 to about 60 wt. %, based on the total weight of the composition, of at least one additive.

10. The process according to claim 9, further comprising the step E) homogenizing the combination of step D).

11. A process according to claim 9, wherein the composition at the end of at least one of steps C), D) or E) is in the form of an emulsion.

12. The process according to claim 11, wherein the emulsion is a nanoemulsion or a microemulsion with droplet sizes in the range from 5 nm to 1000 μm.

13. The process according to claim 8, wherein the at least one ester is at least one ester selected from the group consisting of esters formed from at least one C.sub.1 to C.sub.24 monocarboxylic acid with at least one monofunctional alcohol.

14. The process according to claim 8, wherein the at least one ester has a carbon chain distribution of the acid-derived component determined with carbon numbers in the ranges of from 0 to 0.50% C.sub.6, from 4.00% to 7.00% C.sub.8, from 5.00% to 8.00% C.sub.10, from 60.00% to 80.00% C.sub.12, from 10.00 to 20.00% C.sub.14, from 2.00 to 4.00% C.sub.16 and from 0.1 to 0.60% C.sub.18.

15. The process according to claim 8, wherein the at least one ester has a carbon chain distribution of the acid-derived component with carbon numbers in the ranges of from 0 to 2.00% C.sub.6, from 0 to 10.00% C.sub.8, from 0 to 10.00% C.sub.10, from 0 to 5.00% C.sub.16 and from 0 to 1.00% C.sub.18.

16. A drilling composition obtainable by a process according to claim 8 and having at least one of the properties: γ1) a plastic viscosity measured at 50° C. in the range from 15 to 75 mPa.Math.s; γ2) a yield point measured at 50° C. in the range from 5 to 45 lb/100 ft.sup.2 (2.4 to 21.6 Pa); or γ3) a gel strength measured at 50° C. in the range from 4 to 25 lb/100 ft.sup.2 (1.9 to 12 Pa).

17. (canceled)

18. A drilling system comprising a drill head, a drill string, a reservoir for drilling composition and a drilling composition according to claim 1.

19. A process for making a borehole comprising the steps: a1) providing a composition according to claim 1; a2) drilling a hole in a subterranean formation; and a3) circulating the composition provided in a1) at least partially in the hole at least partially while drilling.

20. A process for conveying cuttings from a hole drilled in a subterranean formation, comprising the steps: b1) providing a composition according to claim 1, and b2) circulating the composition provided in b1) at least partially in the hole.

21. The process according to claim 20, wherein the composition is circulated at least partially while drilling the hole.

22. A process for treatment of a drill head comprising the steps: c1) providing a composition according to claim 1, and c2) circulating the composition provided in c1) at least partially through the drill head at least partially while the drill head is operated in a subterranean formation.

23. The process according to claim 22, wherein the treatment is at least one of cleaning, cooling or lubrication.

24. A process for production of at least one of oil or gas, comprising the steps: d1) providing a composition according to claim 1, d2) drilling at least one hole in a subterranean formation while at least partially circulating the composition provided in d1) at least partially in the hole; d3) obtaining at least one of oil and gas from the subterranean formation at least partially by means of the at least one hole drilled in d2); and d4) subjecting the at least one of oil and gas to at least one processing step selected from purifying, refining or treating.

Description

EXAMPLES

Test Methods

Plastic Viscosity (PV), Yield Point (YP), Gel Strength

[0140] Plastic viscosity, yield point and gel strength were measured using a Fann® direct reading viscometer (Model 35 from Fann Instrument Company, Houston, Tex., USA) according to the method described in “Recommended Practice for Field Testing of Oil-based Drilling Fluids”, Upstream Segment, API (American Petroleum Institute) recommended practice 13B-2, Fourth Edition, March 2005, section 6.3, p. 8-10.

Electrical Stability

[0141] Electrical stability was measured using a Fann® electrical stability tester (Model 23D from Fann Instrument Company, Houston, Tex., USA) according to the method described in “Recommended Practice for Field Testing of Oil-based Drilling Fluids”, Upstream Segment, API (American Petroleum Institute) recommended practice 13B-2, Fourth Edition, March 2005, section 10, p. 22-24.

Example 1

[0142] An oil phase was prepared by combining 249.4 ml of PureDrill® HT-40 (Petro-Canada, Canada) with 13.1 ml of a 2-ethylhexyl ester of C.sub.8-C.sub.14 fatty acids obtainable from Cognis Oleochemicals GmbH, Düsseldorf, Germany, under the trade name OMC 586. This oil phase was then combined with 4.2 g of EZ MUL® NT (from the company Halliburton (Baroid), Texas, USA), 87.5 ml of a 25% (by weight) aqueous calcium chloride solution, 3.5 g of DURATONE® HT (from the company Halliburton (Baroid), Texas, USA), 3.5 g of GELTONE® II (from the company Halliburton (Baroid), Texas, USA), Texas, USA), and 280 g of barite. Rheological parameters were determined at 50° C. as shown in Table 1 under the heading “before ageing”.

[0143] The mixture was aged by treatment in an autoclave in a Baroid roller oven model 70040 at 121° C. (250° F.) for 16 hours according to the method described in “Recommended Practice for Laboratory Testing of Drilling Fluids”, API (American Petroleum Institute) recommended practice 131, Seventh Edition, February 2004/ISO 10416:2002 (modified), section 21, p. 66-73. The electrical stability and rheological parameters were then determined at 50° C. as shown in Table 1 under the heading “after ageing”.

TABLE-US-00001 TABLE 1 Before ageing After ageing Electrical stability (V) n.d. 490 Measured values 600 rpm 49 50 300 rpm 30 31 200 rpm 22 23 100 rpm 14 15  6 rpm 5 6  3 rpm 4 5 Plastic viscosity (cP) 19 19 Yield point (lbf/100 ft.sup.2) 11 12 Gel strength 10 s/10 min (lbf/100 ft.sup.2) 5/6 5/6 n.d. = not determined

Example 2

[0144] The same procedure was followed as that for Example 1, with the difference that 26.2 ml of OMC 586 was used.

Example 3

[0145] To a composition consisting of 249.4 ml of PureDrill® HT-40 (Petro-Canada, Calgary, Canada), 4.2 g of EZ MUL® NT (from the company Halliburton (Baroid Fluid Services), Texas, USA), 87.5 ml of a 25% (by weight) aqueous calcium chloride solution, 3.5 g of DURATONE® HT (from the company Halliburton (Baroid Fluid Services), Texas, USA), 3.5 g of GELTONE® II (from the company Halliburton (Baroid Fluid Services), Texas, USA), Texas, USA), and 280 g of barite., was added 13.1 ml of OMC 586 (Cognis Oleochemicals GmbH, Düsseldorf, Germany).

Example 4

[0146] The same procedure was followed as that for Example 3, with the difference that 26.2 ml of OMC 586 was added.

Example 5

[0147] The procedure of Example 1 was followed, with the difference that 1.5 g of the structure building agent GELTONE II was used. The yield point of the product before ageing by heat rolling as described for Example 1 was 8 lb/100 ft.sup.2. The yield point of the product after ageing by hot rolling as described for Example 1 was 10 lb/100 ft.sup.2.

Example 6

Rate of Penetration (ROP)

[0148] Boreholes were drilled using the compositions of Examples 1 to 4 as drilling fluid, and the respective rate of penetration measured as distance per hour. The rock formation which was drilled into, the drilling equipment, weight on bit, and rotation speed (rpm), were maintained effectively constant for each test, so that the only variable was the drilling fluid. In this way, comparative data were obtained for the different compositions. The results are shown in Table 2.

TABLE-US-00002 TABLE 2 Example Penetration rate test result 1 very good 2 good 3 satisfactory 4 satisfactory

[0149] Drilling into subterranean formations, whether onshore or offshore, is accompanied by substantial costs. It is thus advantageous to reduce overall drilling time. Penetration rate, while not being the sole factor determining overall drilling time, provides a considerable contribution thereto. Faster penetration rates are therefore desirable. The above results show that the composition according to the invention, and in particular the use of the above-described esters in combination with a saturated hydrocarbon (paraffin) as described above, results in improved penetration rates when drilling, thereby contributing to reducing overall drilling time.