SYSTEM AND RELATED METHOD TO SEAL FRACTURED SHALE

Abstract

A method of pumping a fluid and reactive solid into a mineral formation includes the fluid reacting with the mineral formation to produce a nucleation product. The method may be used in shale formations to seal fissures and prevent leakage. The fluid used in this method may comprise CO.sub.2 and the nucleation products may be the products of carbonation reactions. A cement formed by reacting CO.sub.2 with a reactive solid under deep geological formation conditions is also disclosed.

Claims

1. A method comprising pumping a fluid and reactive solid into a mineral formation, wherein said fluid reacts with said solid to produce a solid reaction product.

2. The method of claim 1, wherein the solid reaction product is one or more of a carbonate and a silicate.

3. The method of claim 1, wherein the solid reaction product is a product of a carbonation reaction.

4. The method of claim 1, wherein the fluid comprises CO.sub.2.

5. The method of claim 1, wherein the fluid comprises water and CO.sub.2.

6. The method of claim 1, wherein the reactive solid comprises a mineral.

7. The method of claim 6, wherein the mineral is comprised of one or more of quartz, calcite, amorphous silica, dolomite, kaolinite, illite, and mica.

8. The method of claim 7, wherein the mica comprises one or more of phlogopite, muscovite, and biotite.

9. The method of claim 1, wherein the reactive solid comprises a divalent silicate.

10. The method of claim 9, wherein the reactive solid comprises one or more of magnesium and calcium silicate.

11. The method of claim 1, wherein the reactive solid comprises a material selected from one or more of brucite (Mg(OH)2), chrysotile (Mg.sub.3Si.sub.2O.sub.5(OH).sub.4), forsertite (Mg.sub.2SiO.sub.4), harzburgite (CaMgSi.sub.2O.sub.6+(Fe,Al)), olivine ((Mg,Fe).sub.2SiO.sub.4), orthopyroxene CaMgSi.sub.2O.sub.6+(Fe,Al)), serpentine (Mg.sub.3Si.sub.2O.sub.5(OH).sub.4), and wollastonite (CaSiO.sub.3).

12. The method of claim 11, wherein the reactive solid comprises wollastonite (CaSiO.sub.3).

13. The method of claim 1, wherein the reactive solid comprises an alkaline waste product material.

14. The method of claim 13, wherein the alkaline waste product comprises a material selected from one or more of blast furnace slag from steel manufacturing, bottom ash, fly ash, kiln dust, mine tailings, municipal solid waste ash, paper mill waste, and steelmaking slag.

15. The method of claim 1, wherein the reaction occurs at conditions typical to a deep geological formation.

16. The method of claim 1, wherein the reaction occurs at 15-25 MPa.

17. The method of claim 16, wherein the reaction occurs at 18-22 MPa.

18. The method of claim 1, wherein the reaction occurs at 40-175° C.

19. The method of claim 18, wherein the reaction occurs at 70-100° C.

20. The method of claim 1, wherein said reaction occurs via a dissolution reaction in which a solid donates a divalent cation, followed by a precipitation reaction in which a solid phase material nucleates within the mineral formation.

21. The method of claim 1, wherein said mineral formation is a fractured shale formation.

22. The method of claim 1, wherein said mineral formation is comprised of one of is a wellbore material, a porous mineral formation; and a fractured mineral formation

23. The method of claim 21, wherein said carbonate material partially or completely closes fractured shale formation.

24. The method of claim 21, wherein said reaction product cements the mineral formation.

25. The method of claim 1, wherein said solid reaction product partially or completely seals a fissure in the mineral formation.

26. The method of claim 21, wherein the fluid further comprises a proppant.

27. The method of claim 21, wherein the reactive solid comprises a proppant.

28. The method of claim 1, wherein the method is used to sequester carbon.

29. The method of claim 21, wherein the method is used to stabilize fractured shale to reduce seismicity.

30. The method of claim 21, wherein the method is used to decrease fluid connectivity to minimize leakage.

31. The method of claim 1, wherein the reactive solid is first added, and the fluid is added later.

32. The method of claim 1, wherein the reactive solid is added along with a cement mixture.

33. The method of claim 1, wherein the reactive solid comprises nanoparticles.

34. The method of claim 33, wherein the nanoparticles are designed to target leaking fractures in shale.

35. The method of claim 1, wherein the fluid further comprises a surfactant.

36. The method of claim 1, wherein the fluid further comprises a lubricant.

37. The method of claim 1, wherein the fluid further comprises polyolefin.

38. The method of claim 1, wherein the method is used for enhanced oil recovery.

39. The method of claim 1, wherein the method is used to recover methane from methane hydrate formations.

40. A cement formed by reacting carbon dioxide with a reactive solid under deep geological formation conditions.

41. The cement of claim 40, wherein the cement comprises a carbonate, a silicate, or a mixture of carbonates and silicates.

42. The cement of claim 40, wherein the deep geological formation conditions comprise a pressure of 15-25 MPa.

43. The cement of claim 42, wherein the deep geological formation conditions comprise a pressure of 18-22 MPa.

44. The cement of claim 40, wherein the deep geological formation conditions comprise a temperature of 40-175° C.

45. The cement of claim 44, wherein the deep geological formation conditions comprise a pressure of 70-100° C.

46. The cement of claim 40, wherein the reactive solid comprises a mineral.

47. The cement of claim 40, wherein the mineral is comprised of one or more of quartz, calcite, amorphous silica, dolomite, kaolinite, illite, and mica.

48. The cement of claim 47 wherein the mica comprises one or more of phlogopite, muscovite, and biotite.

49. The cement of claim 40, wherein the reactive solid is an alkaline waste product material.

50. The cement of claim 49, wherein the alkaline waste product comprises a material selected from one or more of blast furnace slag from steel manufacturing, bottom ash, fly ash, kiln dust, mine tailings, municipal solid waste ash, paper mill waste, and steelmaking slag.

51. The cement of claim 40, wherein the reactive solid comprises a divalent silicate.

52. The cement of claim 51, wherein the reactive solid comprises a magnesium or calcium silicate.

53. The cement of claim 40, wherein the reactive solid comprises a material selected from one or more of brucite (Mg(OH).sub.2), chrysotile (Mg.sub.3Si.sub.2O.sub.5(OH).sub.4), forsertite (Mg.sub.2SiO.sub.4), harzburgite (CaMgSi.sub.2O.sub.6+(Fe,Al)), olivine ((Mg, Fe).sub.2SiO.sub.4), orthopyroxene (CaMgSi.sub.2O.sub.6+(Fe,Al)), serpentine (Mg.sub.3Si.sub.2O.sub.5(OH).sub.4), and wollastonite (CaSiO.sub.3).

54. The cement of claim 53, wherein the reactive solid comprises wollastonite (CaSiO.sub.3).

55. The cement of claim 40, wherein the reactive solid comprises nanoparticles.

56. The cement of claim 55, wherein the nanoparticles are designed to target leaking fractures in shale.

57. The cement of claim 40, wherein the cement reduces the porosity and permeability of a mineral formation.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0007] FIG. 1 shows an exemplary application of a method of the invention, wherein this method is used in a shale gas extraction operation.

[0008] FIG. 2 is a micrograph showing shale particles before and after carbonization according to a method of the invention.

DETAILED DESCRIPTION

[0009] A method of pumping a fluid and a reactive solid into a mineral formation, wherein the fluid reacts with the mineral formation to produce a solid reaction product is disclosed. In one embodiment the fluid comprises CO.sub.2. In another embodiment the fluid comprises water and CO.sub.2. In one embodiment the solid reaction product is the result of a carbonation reaction. In another embodiment the solid reaction product is a calcite, amorphous silica, or other nucleation or precipitation product. In one embodiment the CO.sub.2 is supercritical CO.sub.2. In another embodiment the CO.sub.2 is from a waste stream. In one embodiment the water is a solution of carbonates. In another embodiment the carbonates have a concentration of greater than or equal to 0.1 M, or greater than or equal to 1.0 M, or greater than or equal to 10.0 M. In one embodiment the carbonates are carbonic acid, in another embodiment the carbonates are bicarbonates. In some embodiments the water is an alkaline solution. In some embodiments the alkaline solution has a pH of 7 or greater, or 8 or greater, or 9 or greater, or 10 or greater, or 11 or greater, or 12 or greater.

[0010] In one embodiment, the reactive solid comprises a mineral. In another embodiment the mineral is comprised of one or more of quartz, calcite, amorphous silica, dolomite, kaolinite, illite, mica, and others. In another embodiment the mica comprises one or more of phlogopite, muscovite, biotite, and others. In another embodiment the reactive solid comprises a divalent silicate. In another embodiment the reactive solid comprises one or more of magnesium and calcium silicate. In another embodiment the reactive solid comprises a material selected from one or more of brucite (Mg(OH).sub.2), chrysotile (Mg.sub.3Si.sub.2O.sub.5(OH).sub.4), forsertite (Mg.sub.2SiO.sub.4), harzburgite (CaMgSi.sub.2O.sub.6+(Fe,Al)), olivine ((Mg,Fe).sub.2SiO.sub.4), orthopyroxene CaMgSi.sub.2O.sub.6+(Fe,Al)), serpentine (Mg.sub.3Si.sub.2O.sub.5(OH).sub.4), wollastonite (CaSiO.sub.3), and others. In another embodiment the material consists of wollastonite (CaSiO.sub.3).

[0011] In one embodiment the reactive solid comprises an alkaline waste product material. In another embodiment the alkaline waste product comprises a material selected from one or more of blast furnace slag from steel manufacturing, bottom ash, fly ash, kiln dust, mine tailings, municipal solid waste ash, paper mill waste, steelmaking slag, and others.

[0012] In one embodiment of the method the reaction occurs at conditions typical of a deep geological formation, for example a formation located 1000 meters below ground or deeper, or 1500 meters below ground or deeper, or 2000 meters below ground or deeper, or 2500 meters below ground or deeper, or 3000 meters below ground or deeper. For example, the reaction may occur at different pressures. In another embodiment the reaction occurs at 15-25 MPa. In another embodiment the reaction occurs at 18-22 MPa. The reaction may also occur within a range of different temperatures. In another embodiment the reaction occurs at 40-175° C. In another embodiment the reaction occurs at 70-100° C. In some embodiments the reaction may be pressurized by a pump.

[0013] In one embodiment of the method the reaction occurs via a dissolution reaction in which a solid donates a divalent cation, followed by a precipitation reaction in which a solid phase material nucleates within the mineral formation.

[0014] In one embodiment of the method the mineral formation is a fractured shale formation. In another embodiment the mineral formation is wellbore material. In another embodiment the mineral formation is a porous mineral formation, in another embodiment the mineral formation is a fractured mineral formation. In another embodiment an analysis is performed to determine optimum chemistry for a particular application.

[0015] In one embodiment of the method the carbonate material partially or completely seals a fissure in the mineral formation. In another embodiment the carbonate material partially or completely closes a fractured shale formation. In another embodiment the carbonate material cements the shale formation.

[0016] In one embodiment the fluid further comprises a proppant. In another embodiment the reactive solid comprises a proppant. In one embodiment the fluid further comprises a lubricant. In another embodiment the fluid further comprises a surfactant. In another embodiment the fluid is further comprised of polyolefin.

[0017] In one embodiment the method is used to sequester carbon. In another embodiment the method is used to stabilize fractured shale to reduce seismicity. In another embodiment the method is used to decrease fluid connectivity to minimize leakage. In another embodiment the decrease in fluid connectivity reduces the porosity and permeability of the mineral formation. In another embodiment the reactive solid is used as a proppant, allowing the formation to settle back to its pre-fracture geometry.

[0018] In one embodiment of the method the reactive solid is first added, and the fluid is added later. In another embodiment the reactive solid is added along with a cement mixture.

[0019] In one embodiment the reactive solid comprises nanoparticles. In another embodiment the nanoparticles are designed to target leaking fractures in a mineral formation.

[0020] In one embodiment the method is used for enhanced oil recovery. In another embodiment the method is used to recover methane from methane hydrate formations.

[0021] Another aspect of this disclosure relates to a cement formed by reacting carbon dioxide with a reactive solid under deep geological formation conditions. In one embodiment the cement is a carbonate, a silicate, or a mixture of carbonates and silicates. In one embodiment the deep geological formation conditions comprise a pressure of 15-25 MPa. In another embodiment the deep geological formation conditions comprise a pressure of 18-22 MPa. In another embodiment the deep geological formation conditions comprise a temperature of 40-175° C. In another embodiment the deep geological formation conditions comprise a pressure of 70-100° C.

[0022] In one embodiment the cement reduces the porosity and permeability of a mineral formation.

DETAILED DESCRIPTION OF THE FIGURES

[0023] FIG. 1 shows one potential embodiment of the method. In this embodiment, the method is used to seal a shale formation. In FIG. 1a, a conventional shale fracturing well operation is shown. A borehole 101 in the shale, containing a casing 102 is used to extract natural gas 105. Off of the borehole 101 may exist fractures 104 and organic materials such as kerogen 103 contained therein. Proppants 100 are used to maintain well integrity and aid in extraction of natural gas.

[0024] FIG. 1b shows one potential embodiment of the method of this disclosure. FIG. 1b shows a fluid 111 being pumped into the borehole along with a reactive solid 110. The fluid and reactive solid flow into the fissures and begin to react with the surrounding shale to form carbonates. FIG. 1c shows the end result of the method in this embodiment, wherein a solid carbonate has formed 122 along with other possible solid byproducts such as silica 121. These solid byproducts close the fissure 123, sealing the well and trapping the CO.sub.2 120.

[0025] FIG. 2 shows an electron micrograph of shale particles used in Example 1 below. FIG. 2 shows the shale particles before FIG. 2a and after FIG. 2b reaction with the fluid. Precipitated solid material is visible in FIG. 2b as a bulky surface coating on the shale particles.

Example 1

[0026] Shale samples were obtained from Ward's Scientific (Oil Shale #47E7477). CaSiO.sub.3 (99%) and CaCO.sub.3 (99%) were obtained from Sigma-Aldrich. Food-grade liquid CO.sub.2 was supplied by Robert's Oxygen. All reagents were used as received. Solid shale samples were ground using miller jars and sieved to obtain particles with diameters in the range of 39-177 μm. Reactants were packed in a stainless steel reactor (MS-13, HIP) at a 1:5 (CaSiO.sub.3:shale) mass ratio with DI water and pressurized with CO.sub.2 to the desired reaction pressure using a syringe pump (500 HP—Teledyne Isco). Temperature control was achieved using an oven (Despatch Inc.) with a shaker to ensure adequate mixing during the experiment. The changes in the composition of the samples were quantified using a PANalytical X'Pert Pro Multipurpose Diffractor (XRD) unit with monochromatic Cu-Kα radiation. TiO.sub.2 was chosen as the internal reference for its distinguishable peaks relative to shale and CaCO.sub.3. The morphological and elemental composition changes of mineral samples were characterized using a Quanta 650 Scanning Electron Microscope (SEM) coupled with energy dispersive X-ray (EDS) spectroscopy.

[0027] Quantitative XRD analyses were carried out to determine the extent of reaction and conversion of wollastonite to calcite at pressure and temperature combinations characteristic of shale formations. An internal TiO2 standard was used to calibrate the intensity of calcite peaks. The results summarized in Table 1 indicate that the reaction achieved greater than 50% conversion (measured in terms of CaCO3 generation) after 24 hours.

TABLE-US-00001 TABLE 1 Mineral CO.sub.2 Pressure Temperature Conversation Composition (MPa) (° C.) Extent 50% Shale + 50% 21.4 75 55 ± 2% CaSiO.sub.3 50% Shale + 50% 21.4 95 58 ± 1% CaSiO.sub.3 50% Shale + 50% 15.2 75 50 ± 1% CaSiO.sub.3

Example 2

[0028] Adhesion was studied under both equilibrium and dynamic conditions under reservoir pressure and temperature conditions (50° C. and 20 MPa) and a range of pH and ionic strength in fresh and carbonated synthetic brines on pendant droplets using methods previously reported (Wang et al., Environ. Sci. Technol. 2013, 47 (1), 234-241). Seven representative minerals including quartz, calcite, amorphous silica, dolomite, kaolinite, illite, and phlogopite mica were selected since these constitute most of the minerals on the pore surfaces in sandstones (Peters, Chem. Geol. 2009, 265 (1-2), 198-208). These minerals all have hydroxyl functional groups, for example, aluminol, silanol, silanediols and bridged hydroxyls, at the solid surface and are sensitive to the adjacent aqueous phase pH and ionic strength conditions. Phlogopite mica was selected as a model mica species recognizing that many of the surface characteristics of interest in adhesion (e.g., surface functional groups, surface roughness) are shared by other mica species (i.e., muscovite and biotite).

[0029] Mineral samples were prepared by sectioning high purity rocks (Ward's Natural Science), lapping the experimental surface according to the crystal structure with a diamond grinding wheel, and then polishing them with a series of silicon carbide sanding papers down to a roughness of 1-5 μm. Some of the surfaces did not need polishing. Phlogopite cleaved easily into basal plane sheets to create surfaces that are smooth on the scale of 10 s of nanometers. The high-purity amorphous silica was not polished and used as received since it was polished at the factory (Heraeus Quarzglas). Some of the phlogopite and silica surfaces were made rougher using the sand papers in order to study the effect of roughness on adhesion. Roughness was measured using a profilometer (Dektak 8, Veeco) for the rough surfaces and an AFM (Asylum Research cypher scanning probe microscope) for smooth surfaces. Before experiments, all equipment and samples were carefully cleaned following the protocol previously described (Wang et al., Water Resour. Res. 2012, 48, (8), W08518; Wang et al., Environ. Sci. Technol. 2013, 47 (1), 234-241). Extensive care was taken to exclude any source of contamination, especially organic matter which could strongly affect wettability. All samples were flushed with at least 200 mL (˜10 times pressure vessel volume) brine solution over 1 h to equilibrate the surfaces of the minerals with the aqueous phase. All experiments were repeated at least three times.

[0030] To evaluate adhesion of CO.sub.2 droplets on the mineral surface, a modified form of the advancing/receding contact angle measurement was carried out. To more closely approximate the mechanics of the ‘stick-peel-crack’ tests used to measure axial tensile force in solid mechanics, which is proportional to the adhesive energy and work of adhesion (Kendall, Science. 1994, 263, 1720-1725), we positioned the injection needle 1.5-3 mm below the surface and then outfitted the injection tubing with two pin valves. These two pin valves in sequence allowed for the precise control of captive CO.sub.2 droplet flows into and out of the pressure cell by regulating the relative pressure of the pure CO.sub.2 in the space between the valves and the pressure in the vessel. N.sub.2 control experiments were conducted under identical conditions on phlogopite and silica surfaces. Adhesion was determined based on the tendency of a CO.sub.2 droplet to stick to the mineral surface under tensile force created by the pressure difference between the injection needle and the pressure vessel. Irregular contact lines and increased wettability were also common qualitative characteristics of adhered droplets. Table 1 explores the relationship between adhesion, ionic strength, and pressure. Table 2 explores the relationship between adhesion, mineral composition, roughness, and pressure. Experiments for Table 3 were performed at an ionic strength of 1.5 M NaCl. The error range in Tables 2 and 3 represent one standard deviation, and it should be noted that negative percentage is not realistic.

TABLE-US-00002 TABLE 2 P.sub.CO2 (MPa) 0 20 Ionic Strength (M) Droplets Adhered (%) Phlogopite and CO.sub.2 0.00 26 ± 13 19 ± 11 0.10 49 ± 14 82 ± 17 0.46 58 ± 25 76 ± 13 0.86 52 ± 17 71 ± 23 1.21 55 ± 22 79 ± 7  Silica and CO.sub.2 0.00  9 ± 16 26 ± 44 1.21 38 ± 49 31 ± 54 Phlogopite and N.sub.2 0.00 24 ± 15 30 ± 22 1.21 35 ± 20 23 ± 21 Silica and N.sub.2 0.00 74 ± 46 66 ± 53 1.21 66 ± 54 67 ± 55

TABLE-US-00003 TABLE 3 Roughness Droplets Adhered (%) Mineral (nm) 0 MPa CO.sub.2 20 MPa CO.sub.2 phlogopite 6.4 ± 1.0 55 ± 12 79 ± 7  1600 ± 472  4 ± 6 11 ± 13 calcite 1.9 ± 1.4 8 ± 4 6 ± 6 4725 ± 1195 2 ± 1 1 ± 1 amorphous 5.8 ± 1.8 38 ± 49 31 ± 54 silica 2300 ± 360  1 ± 1 1 ± 0