Methods Of Cementing And Lassenite-Containing Cement Compositions

Abstract

Cement compositions and methods of making the same are provided. The composition comprises cement or lime, water and Lassenite, a pozzolanic strength retrogression inhibitor.

Claims

1. A cement composition, comprising: cement; an aqueous fluid present in an amount from about 20% to about 80% by weight of the cement; a pozzolan present in an amount from about 10% to about 40% by weight of the cement; and a modifying additive selected from lime, weighting additives, and dispersants; wherein the pozzolan comprises a crystalline porous aluminosilicate and is a strength retrogression inhibitor; and wherein the compressive strength of the cement composition is at least 50 psi three hours after curing at 190 F. and the compressive strength of the cement composition measured at 72 hours is greater than the compressive strength of the cement composition measured at 24 hours.

2. The cement composition of claim 1, wherein the cement is selected from Portland cements, gypsum cements, high alumina content cements, slag cements, high magnesia content cements, shale cements, acid/base cements, fly ash cements, zeolite cement systems, kiln dust cement systems, microfine cements, metakaolin, and combinations thereof

3. The cement composition of claim 1, wherein the aqueous fluid is water selected from fresh water, brackish water, saltwater, and any combination thereof

4. The cement composition of claim 1, wherein the aqueous fluid is water in an amount selected from about 20% to about 80% by weight of the cement, about 28% to about 60% by weight of the cement, and about 36% to about 66% by weight of the cement.

5. The cement composition of claim 4, wherein the pozzolan further comprises silicon dioxide (SiO.sub.2) and aluminum oxide (Al.sub.2O.sub.3).

6. The cement composition of claim 5, wherein the silicon dioxide (SiO.sub.2) and aluminum oxide (Al.sub.2O.sub.3), comprise at least 80% by weight of the total oxide content of the pozzolan.

7. The cement composition of claim 5, wherein the silicon dioxide (SiO.sub.2) comprises from about 65% to about 75% by weight of the total oxide content of the pozzolan; and wherein the aluminum oxide (Al.sub.2O.sub.3) comprises from about 10% to about 15% by weight of the total oxide content of the pozzolan.

8. The cement composition of claim 1, wherein the cement composition develops a compressive strength of from about 3200 psi to about 3500 psi at about 24 hours after curing at 190 F.

9. A cementitious composition, comprising: cement a crystalline porous aluminosilicate; a calcium source; and an aqueous fluid; wherein the porous aluminosilicate is a natural pozzolan and a strength retrogression inhibitor; and wherein the compressive strength of the cement composition measured at 72 hours is greater than the compressive strength of the cement composition measured at 24 hours.

10. The cementitious composition of claim 9, wherein the pozzolan comprises silicon dioxide (SiO.sub.2) and aluminum oxide (Al.sub.2O.sub.3).

11. The cementitious composition of claim 10, wherein the silicon dioxide (SiO.sub.2) and aluminum oxide (Al.sub.2O.sub.3), comprise at least 80% by weight of the total oxide content of the pozzolan.

12. The cementitious composition of claim 10, wherein the silicon dioxide (SiO.sub.2) comprises from about 65% to about 75% by weight of the total oxide content of the pozzolan; and wherein the aluminum oxide (Al.sub.2O.sub.3) comprises from about 10% to about 15% by weight of the total oxide content of the pozzolan.

13. The cementitious composition of claim 9, wherein the calcium source comprises lime in an amount of from about 15% to about 40% by weight of the pozzolan.

14. The cementitious composition of claim 9, wherein the aqueous fluid is water selected from fresh water, brackish water, saltwater, and any combination thereof.

15. The cementitious composition of claim 9, wherein the cementitious composition develops a compressive strength of from about 500 psi to about 700 psi at about 24 hours after curing at 180 F.

16. A cementitious composition, comprising: cement; a pozzolan; and an aqueous fluid; wherein the pozzolan comprises a porous aluminosilicate and is a strength retrogression inhibitor; and wherein the compressive strength of the cement composition is at least 50 psi three hours after curing at 190 F. and the compressive strength of the cement composition measured at 72 hours is greater than the compressive strength of the cement composition measured at 24 hours.

17. The cement composition of claim 16, wherein the aqueous fluid is water in an amount selected from about 20% to about 80% by weight of the cement, about 28% to about 60% by weight of the cement, and about 36% to about 66% by weight of the cement.

18. The cement composition of claim 15, wherein the pozzolan comprises silicon dioxide (SiO.sub.2) and aluminum oxide (Al.sub.2O.sub.3); and

19. The cement composition of claim 18, wherein the silicon dioxide (SiO.sub.2) and aluminum oxide (Al.sub.2O.sub.3), comprise at least 80% by weight of the total oxide content of the pozzolan.

20. The cementitious composition of claim 16, further comprising a lime in an amount of from about 15% to about 40% by weight of the pozzolan.

Description

DETAILED DESCRIPTION

[0013] It is to be understood that the following disclosure provides many different embodiments, or examples, for implementing different features of various embodiments. Specific examples of components are described below to simplify and exemplify the present disclosure. These are, of course, merely examples and are not intended to be limiting.

[0014] According to certain embodiments, a cement composition is provided. According to certain embodiments, the cement composition includes cement, an aqueous fluid, and a pozzolanic strength retrogression inhibitor. In certain other embodiments, modifying additives may be included in the cement composition.

[0015] According to certain embodiments, the cement composition includes a hydraulic cement. According to certain embodiments, a variety of hydraulic cements may be utilized, including, but not limited to, those comprising calcium, aluminum, silicon, oxygen, iron, and/or sulfur, which set and harden by a reaction with water. Suitable hydraulic cements include, but are not limited to, Portland cements, gypsum cements, high alumina content cements, slag cements, high magnesia content cements, shale cements, acid/base cements, fly ash cements, zeolite cement systems, kiln dust cement systems, microfine cements, metakaolin, and combinations thereof. In certain embodiments, the hydraulic cement may comprise a Portland cement. The Portland cements that are suitable for use in certain embodiments are classified as Classes A, C, H, and G cements according to the American Petroleum Institute, API Specification for Materials and Testing for Well Cements, API Specification 10, Fifth Ed., Jul. 1, 1990. In certain embodiments, the cement is Class G or Class H cement.

[0016] According to certain embodiments, the cement composition includes an amount of an aqueous fluid sufficient to form a pumpable cementitious slurry. In certain embodiments, the aqueous fluid is water. The water may be fresh water, brackish water, saltwater, or any combination thereof. The water may be present in the cement composition in an amount of from about 20% to about 80% by weight of cement (bwoc), from about 28% to about 60% bwoc, or from about 36% to about 66% bwoc. In certain embodiments, the density of the cement composition in slurry form is from about 7 pounds per gallon (ppg) to about 20 ppg, from about 10 ppg to about 18 ppg, or from about 13 ppg to about 17 ppg.

[0017] According to certain embodiments, the cement composition includes a water-soluble salt. Suitable water-soluble salts include sodium chloride, calcium chloride, calcium bromide, potassium chloride, potassium bromide, magnesium chloride, and any combination thereof. According to certain embodiments, the cement composition may include a water-soluble salt in a range of from about 5% to about 36% by weight of the aqueous fluid.

[0018] According to certain embodiments, the pozzolanic strength retrogression inhibitor includes Lassenite, a crystalline porous aluminosilicate. On the basis of an oxide analysis, Lassenite includes at least silicon dioxide (SiO.sub.2) and aluminum oxide (Al.sub.2O.sub.3). According to certain embodiments, the Lassenite may be present in the cement composition in an amount of from about 10% to about 40% by weight of the cement.

[0019] According to certain embodiments, the Lassenite includes additional oxides, such as sodium oxide (Na.sub.2O), magnesium oxide (MgO), sulfur trioxide (SO.sub.3), potassium oxide (K.sub.2O), calcium oxide (CaO), titanium dioxide (TiO.sub.2), iron (III) oxide (Fe.sub.2O.sub.3), and combinations thereof in any proportion. In certain embodiments, the SiO.sub.2 and Al.sub.2O.sub.3 comprise at least 80% by weight of the total oxides of the Lassenite. According to certain embodiments, the SiO.sub.2 is present in the range of about 65% to about 75% by weight of the total oxides of the Lassenite. According to certain embodiments, the Al.sub.2O.sub.3 is present in the range of from about 10% to about 15% by weight of the total oxides of the Lassenite.

[0020] According to certain embodiments of the cement composition, Lassenite has pozzolanic activity and functions as a strength retrogression inhibitor. Specifically, according to certain embodiments, cement compositions that include Lassenite attain a compressive strength of 50 psi after curing for about 2 to about 3 hours at 190 F. Additionally, according to certain embodiments, cement compositions that include Lassenite attain a compressive strength of from about 3200 psi to about 3500 psi after curing for about 24 hours at 190 F.

[0021] According to certain embodiments of the cement composition, Lassenite not only functions as a strength retrogression inhibitor, Lassenite also increases the compressive strength of cement compositions including Lassenite. In certain embodiments of the present invention, the compressive strength of cement compositions including Lassenite increased by a factor of from about 5% to about 10% when measured from about 24 to about 72 hours after cure at a temperature of 300 F. (149 C.) and a pressure of 3,000 psi (20.7 MPa).

[0022] According to certain embodiments, the cement composition includes one or more modifying additives. Such additives include, without limitation, resins, latex, stabilizers, silica, microspheres, aqueous superabsorbers, viscosifying agents, suspending agents, dispersing agents, salts, accelerants, surfactants, retardants, defoamers, settling-prevention agents, weighting materials, fluid loss control agents, elastomers, vitrified shale, gas migration control additives, and formation conditioning agents.

[0023] According to an embodiment, a cementitious composition containing Lassenite, a calcium source, and an aqueous fluid is provided. According to certain embodiments, the calcium source is lime and the lime is present in the cementitious composition in an amount of from about 15% to about 40% by weight of Lassenite (bwol). In certain embodiments, the aqueous fluid is water as described above. In certain other embodiments, the cementitious composition including Lassenite and lime can further include modifying additives as described above. According to certain embodiments, the cementitious composition including Lassenite, lime and water attains a compressive strength of from about 500 psi to about 700 psi at 180 F. after curing for about 24 hours.

[0024] According to certain embodiments, a method for cementing in a subterranean formation is provided. The method comprises introducing a composition into a subterranean formation. According to certain embodiments, the composition includes cement, an aqueous fluid, and Lassenite, as described above. According to certain other embodiments, the composition includes Lassenite, a calcium source and an aqueous fluid, as described above.

[0025] The following examples are illustrative of the compositions and methods discussed above.

EXAMPLES

Oxide Analysis of Lassenite

[0026] Lassenite was obtained from AquaFirst Technologies, Inc. An X-Ray Fluorescence (XRF) oxide analysis was performed on the Lassenite sample and the results are summarized in Table 1, below:

TABLE-US-00001 TABLE 1 Lassenite Composition Oxide Amount (Mole %, by weight) SiO.sub.2 70.54 Al.sub.2O.sub.3 12.44 Na.sub.2O 3.82 MgO 0.82 SO.sub.3 1.6 K.sub.2O 1.48 CaO 2.32 TiO.sub.2 0.62 Fe.sub.2O.sub.3 6.36

Phase Analysis of Lassenite

[0027] An X-Ray Diffraction (XRD) analysis was performed on an exemplary sample of Lassenite. The results are summarized in Table 2, below.

TABLE-US-00002 TABLE 2 Phases present in Lassenite Phase Concentration (%) Clay 54 Quartz 8 Sodium Feldspar 19 Potassium Feldspar 16 Gypsum 3

Pozzolanic Behavior of Lassenite

[0028] In order to assess the pozzolanic behavior of Lassenite, a slurry was formed in which a Lassenite sample was reacted with lime. The composition of the slurry is summarized in Table 3 below:

TABLE-US-00003 TABLE 3 Slurry Design (Density: 13.00 ppg) Materials Amount Water 98.83% by weight of Lassenite (bwol) Lassenite 100% bwol Lime 30% bwol Micromax 20% bwol Coatex XP 1629 0.3 gal/sk CFR-3L 0.3 gal/sk Crush strength at 180 F 24 hours 654 psi 96 hours 1264 psi

[0029] Micromax is a weight additive and CFR-3L is a dispersant that reduces the apparent viscosity and improves the rheological properties of cement slurries. Micromax and CFR-3L are commercially available from Halliburton Energy Services, Inc. Coatex XP 1629 is a carboxylate ether dispersant that reduces the apparent viscosity and improves the rheological properties of a cement slurry. Coatex XP 1629 is commercially available from Coatex, LLC.

[0030] The slurry was cured in a water bath at 180 F. As shown in Table 3, the crush strength of the cured composition was 645 psi and 1264 psi at 24 and 96 hours, respectively. These results confirm the pozzolanic activity of Lassenite.

Cement Slurry Preparation

[0031] Three cement slurries, each having a density of 15.8 ppg and a composition as set forth in Table 4 below, were prepared for testing purposes.

TABLE-US-00004 TABLE 4 Cement Slurry Compositions POZMIX Coatex Water A Lassenite XP Class G (% (% (% 1629 Cement (%) bwoc) bwoc) bwoc) (gal/sk) Cement 100 45.1 Slurry A (No additive) Cement 100 52.8 30 Slurry B (POZMIX A) Cement 100 49.6 30 0.3 Slurry C (Lassenite)

[0032] Cement Slurry A included only cement and water. Cement Slurry B included cement, water and Pozmix A, a pozzolanic cement additive (fly ash) that is made from burned coal and is commercially available from Halliburton Energy Services. The composition of Pozmix A is set forth in Table 5 below.

TABLE-US-00005 TABLE 5 Oxide Composition of POZMIX A Oxide POZMIZ A (% Weight) Al.sub.2O.sub.3 22.3 SiO.sub.2 60.5 K.sub.2O <0.0001 CaO 0.76 Fe.sub.2O.sub.3 3.72

[0033] Cement Slurry C included cement, water, Lassenite and Coatex XP 1629. Cement Slurries A, B and C were dry blended according to API procedure RP 10B-2.

Rheology of the Cement Slurry Containing Lassenite

[0034] The rheology of Cement Slurry C in Table 4 was measured using a Fann 35 viscometer. The results are summarized in Table 6 below.

TABLE-US-00006 TABLE 6 Rheology of Cement Slurry (75 F.) Fann 35 Viscometer readings RPM 3 6 30 60 100 200 300 600 Dial Readings 18 24 27 41 57 97 148 252

[0035] In Table 6 above, a higher Dial Reading indicates a higher viscosity, and therefore less pourability and pumpability. The results shown in Table 6 are within the range that demonstrate that Cement Slurry C which includes Lassenite, was pourable and could be pumped easily.

Compressive Strength Test

[0036] Cement Slurries A, B, and C from Table 4 were cured at a constant temperature of 190 F. The compressive strength of the cured samples of Cement Slurries A, B and C from Table 4 were tested for the time it took the samples to reach a compressive strength of 50 psi, and again for their compressive strength at 24 hours using a UCA (Ultrasonic Cement Analyzer). According to typical oilfield processes, a cement slurry must develop a compressive strength of at least 50 psi before commencing further drilling of a well. Therefore, the shorter the time it takes for a cement slurry to reach a compressive strength of 50 psi, the more desirable that cement slurry is for use in oilfield processes. Table 7 summarizes the results of the compressive strength testing.

TABLE-US-00007 TABLE 7 Compressive strength at 190 F. Time for 50 24 hours psi compressive HR:MM strength Cement Slurry A 2:19 2517 Cement Slurry B 2:03 3493 Cement Slurry C 2:53 3277

[0037] The results shown in Table 7 demonstrate that Cement Slurry C which includes Lassenite develops compressive strength at a rate and amount which is comparable to Cement Slurry B which includes Pozmix A. The initial strength development (50 psi) of Cement Slurry C which includes Lassenite was slightly delayed compared to Cement Slurry B which includes Pozmix A. It is suspected that this is due to the presence of Coatex XP 1629 in Cement Slurry C.

Strength Retrogression Test

[0038] Cured samples made from Cement Slurries A, B, and C from Table 4 as well as Cement Slurry D which had a density of 15.8 ppg and included Class G cement, 35% bwoc of SSA-2 and 56.03% bwoc of water and was prepared in the same manner as Cement Slurries A, B, and C, were tested for strength retrogression. SSA-2 is coarse silica flour comprised of Oklahoma No. 1 dry sand and is commercially available from Halliburton Energy Services. Strength retrogression was determined by measuring the compressive strength of each of Cement Slurries A, B, C and D at 24 hours and 72 hours and determining the percent change in compressive strength over this time period. Table 8 summarizes the results of the strength retrogression testing.

TABLE-US-00008 TABLE 8 Strength Retrogression at 300 F. Compressive Strength (psi) 6 12 24 48 72 % Hours Hours Hours Hours Hours Change Slurry A 1731 2442 2748 2609 2470 10.12 Slurry B 2058 2510 2648 2350 2418 8.69 Slurry C 1710 1957 2205 2416 2384 +8.12 Slurry D 1569 2023 2267 2292 2275 +0.35

[0039] As shown in Table 8, Cement Slurry C which included Lassenite did not experience strength retrogression and actually increased in compressive strength from 24 hours to 72 hours. This is a significant result compared to the results for Cement Slurry B which included Pozmix A which experienced a decrease in compressive strength or a strength retrogression of 8.69% from 24 hours to 72 hours.

[0040] While the present invention has been described in terms of certain embodiments, those of ordinary skill in the art will recognize that the invention can be practiced with modification within the spirit and scope of the appended claims.

[0041] The present disclosure has been described relative to certain embodiments. Improvements or modifications that become apparent to persons of ordinary skill in the art only after reading this disclosure are deemed within the spirit and scope of the application. It is understood that several modifications, changes and substitutions are intended in the foregoing disclosure and in some instances some features of the invention will be employed without a corresponding use of other features. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention.