Microencapsulated oil field chemicals

• US 6,326,335 B1
• Filed: 07/13/1999
• Issued: 12/04/2001
• Est. Priority Date: 05/05/1992
• Status: Expired due to Term

• Current Assignee: Ecolab USA Incorporated (Ecolab, Inc.)
• Original Assignee: Corsicana Technologies, Inc. (Ecolab, Inc.)
• Inventors: Pike, Robert Wayne, Kowalski, Thomas Charles
• Primary Examiner(s): TUCKER, PHILIP C
• Application Number:
  US09/360,370
• Time in Patent Office: 875 Days
• Field of Search: 507/241, 507/244, 507/239, 507/261, 507/902, 507/939, 507/129, 507/131, 507/133, 264/4.3, 428/402.2
• US Class Current: 507/241
• CPC Class Codes: C09K 8/536 characterised by their form or by the form of their components, e.g. encapsulated material
• CPC Class Codes: C09K 8/54 Compositions for in situ inhibition of corrosion in boreholes or wells
• CPC Class Codes: C09K 8/92 characterised by their form or by the form of their components, e.g. encapsulated material C09K8/70 takes precedence
• CPC Class Codes: Y10S 507/902 Controlled release agent
• CPC Class Codes: Y10S 507/939 Corrosion inhibitor
• CPC Class Codes: Y10T 428/2984 Microcapsule with fluid core [includes liposome]

Abstract

Gelatin capsules containing oil field chemicals, preferably weighted with a heavy metal compound, are made more stable under certain conditions by the incorporation of a strong chelating agent. The microcapsules can provide an extended treatment period since many materials that would damage the microcapsules are controlled by the chelating agent.

Claims

1. A microcapsule containing from about 5% to about 80% of oil field chemical selected from the group consisting, of:

(A) scale inhibitor;

(B) corrosion inhibitor;

(C) biocide;

(D) chemicals to limit the presence of solid hydrocarbons;

(E) scavengers for H₂S and/or O₂;

(F) demulsifier;

(G) clay stabilizer;

(H) surfactant;

(I) acidizing agent; and

(J) mixtures thereof,

said microcapsules having a wall comprising

a gelatin;

an effective amount of weighting agent;

an effective amount of a chelating agent selected from the acids and salts consisting of;

(1) a compound having the generic formula;

2. The microcapsule of claim 1 wherein the effective amount of the weighting agent is from about 5 percent to about 75 percent by weight.

3. The microcapsule of claim 2 wherein the weighting agent is a barium salt.

4. The microcapsule of claim 1 where in the effective amount of the weighting agent is from about 10 percent to about 50 percent by weight.

5. The microcapsule of claim 4 wherein the weighting agent a barium salt.

6. The microcapsule of claim 1 wherein the wall is formed by precipitating the gelatin with at least one salt selected from the group consisting of sodium sulfate, ammonium sulfate and mixtures thereof.

7. A mixture of microcapsules comprising

a first microcapsule defined by claim 1 which contains an a first oil field chemical;

a second microcapsule defined by claim 1 which contains a second oil field chemical that is different from the first oil field chemical.

8. The mixture of microcapsules of claim 7 wherein the first and second microcapsules contain different oil chemicals selected from the group consisting of corrosion inhibitors, scale inhibitors and biocides.

9. A composition comprising a slurry of microcapsules at a level from about 10 percent to about 80 percent by weight in the supernatant liquid used to form the microcapsules, the microcapsules defined by claims 1, 6, 7 or 8.

10. A method of treating an oil well, comprising the step of:

treating an oil well having high levels of brine and/or heavy metals with a composition of microcapsules that is defined by claims 1, 6, 7 or 8, the treating provided for a period of time of at least about one month.

11. A method of treating an oil well, comprising the step of:

treating an oil well having high levels of brine and/or heavy metals with a composition of microcapsules that is defined by claim 9, the treating provided for a period of time of at least about one month.