Cement compositions containing degradable materials and methods of cementing in subterranean formations

a technology of degradable materials and cement compositions, which is applied in the direction of ceramicware, sealing/packing, and well accessories, etc., can solve the problems of inability to meet the requirements of subterranean cementing operations

Inactive Publication Date: 2007-05-03
REDDY B RAGHAVA +4
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The degradable cement compositions effectively reduce cement slurry loss, enhance zonal isolation, and improve the ability to withstand cyclic stresses and impacts, ensuring better well integrity and operational efficiency.

Problems solved by technology

Subterranean formations traversed by well bores naturally may be weak, extensively fractured, and highly permeable.
In some cases, if the fracture gradient of the formation is exceeded by the hydrostatic head pressure normally associated with cement pumped into the well bore, the formation will fracture.
This may result in the loss of cement into the extensive fractures of the formation.
This can be problematic because, inter alia, less cement composition will remain in the annular space to form the protective sheath that bonds the pipe string to the walls of the well bore.
However, the use of polypropylene flakes may be undesirable because the polymer is not biodegradable.
Mineral flakes such as mica often have unsuitable sizes that preclude their use.
However, these methods may be problematic because, inter alia, they can require elaborate and expensive equipment, which may not be accessible for use in remote areas.
Certain conventional cement compositions also may become brittle and / or inelastic at some point after setting into a cement sheath.
This may be problematic because, inter alia, an excessively brittle or inelastic cement sheath may become unable to provide desired zonal isolation, and may require costly remediative operations.
This may be particularly problematic in the case of multilateral wells.
If the cement sheath in the area of the junction between a principal well bore and a lateral well bore in a multilateral well is excessively brittle or inelastic, it may be unable to withstand impacts that may occur, e.g., when tools used in drilling and completing the well collide with casing in the junction area as the tools are moved in and out of the well.
Well bores that comprise an expandable tubular present another scenario where an excessively brittle or inelastic cement sheath may be problematic.
The expansion of an expandable tubular inadvertently may crush at least a portion of the cement sheath behind the tubular, thereby impairing the cement sheath's ability to provide the desired zonal isolation.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

[0033] Sample cement compositions were prepared in accordance with API Recommended Practice 10B, Twenty-Second Edition, 1997.

[0034] Sample Composition No. 1 comprised Class A cement and about 37.85% water bwoc. Sample Composition No. 1 was cured for 1 day at a temperature of 210° F. and a pressure of 1000 psi.

[0035] Sample Composition No. 2 comprised Class A cement, about 8% bwoc polylactic acid (“PLA”) in bead form (about 0.75 mm in diameter), and about 37.85% water bwoc. Sample Composition No. 2 was cured for 1 day at a temperature of 210° F. and a pressure of 1000 psi. The density of Sample Composition No. 2, upon setting, was measured at 16.4 lb / gallon.

[0036] Sample Composition No. 3 comprised Class A cement, PLA at about 8% bwoc and about 37.85% water bwoc. Sample Composition No. 3 was cured for 14 days at a temperature of 210° F. and a pressure of 1000 psi. The density of Sample Composition No. 3, upon setting, was measured at 16.3 lb / gallon.

[0037] The sample cement compos...

example 2

[0039] The Young's Modulus of Sample Composition Nos. 1 and 2 was determined after each Sample Composition had cured. The Young's Modulus was measured by performing Load vs. Displacement measurements on MTS Load Frame equipment under unconfining conditions. The results are set forth in Table 2.

TABLE 2Degradable materialComposition(% bwoc)Young's Modulus (psi)Sample CompositionNone  2 × 106No. 1Sample CompositionPLA1.22 × 106No. 28% bwoc

[0040] The above example demonstrates, inter alia, that the cement compositions of the present invention possess improved elasticity and resiliency.

example 3

[0041] Sample cement compositions were prepared that comprised Class A cement, about 0.375% bwoc CFR-3 dispersant, PLA at about 15% bwoc, and about 33.8% water bwoc. The sample cement compositions were cured for 3 days at a temperature of 190° F. and a pressure of 1000 psi.

[0042] Sample Composition No. 4 did not comprise a retarder.

[0043] Sample Composition No. 5 comprised about 0.5% bwoc HR®-5 retarder.

[0044] Sample Composition No. 6 comprised about 1.0% bwoc of HR®-5 retarder.

[0045] Thickening times at 190° F. were measured according to API procedure. The results of the testing are set forth in the table below.

TABLE 3Retarder concentrationThickening TimeSample Composition(% bwoc)(hrs:min)Sample Composition No. 400:31Sample Composition No. 50.51:00Sample Composition No. 61.01:18

[0046] The above example suggests, inter alia, that the compositions of the present invention can be designed to set at a desired time.

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Abstract

The present invention provides cement compositions that include degradable materials, and methods of using such compositions in subterranean cementing operations. An example of a method of the present invention includes: providing a cement composition that includes a hydraulic cement, and a degradable material; placing the cement composition in a subterranean formation; allowing the cement composition to set therein; and allowing the degradable material to degrade. Another example of a method of the present invention is a method of enhancing the mechanical properties of a cement composition including adding a degradable material to the cement composition and allowing the degradable material to degrade.

Description

CROSS-REFERENCE TO RELATED APPLICATION [0001] This application is a divisional of U.S. patent application Ser. No. 10 / 802,340, filed Mar. 17, 2004, entitled “Cement Compositions Containing Degradable Materials And Methods Of Cementing In Subterranean Formations,” by B. Raghava Reddy, et al., which is incorporated by reference herein for all purposes, from which priority is claimed pursuant to 35 U.S.C. § 120.BACKGROUND [0002] The present invention relates to methods and compositions for use in subterranean cementing operations. More particularly, the present invention relates to cement compositions comprising degradable materials, and methods of using such compositions in subterranean cementing operations. [0003] Hydraulic cement compositions are commonly utilized in subterranean operations, particularly subterranean well completion and remedial operations. For example, hydraulic cement compositions are used in primary cementing operations whereby pipe strings such as casings and li...

Claims

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Application Information

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Patent Type & AuthorityApplications(United States)
IPC IPC(8): C04B24/26C04B14/34C04B28/02C04B38/00C04B38/02C04B40/06C09K8/473C09K8/487E21B33/13
CPCC04B28/02C04B38/02C04B2103/0067C09K8/473C09K8/487E21B33/13C04B24/06C04B24/24C04B24/26C04B24/2611C04B24/2676C04B38/103C04B24/2652C04B2103/40C04B2103/46C04B2111/503
InventorREDDY, B. RAGHAVAZAMORA, FRANKNGUYEN, PHILIP D.MUNOZ, TRINIDAD JR.PALMER, ANTHONY V.
OwnerREDDY B RAGHAVA