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Synthesis of Degradable Polymers Downhole for Oilfield Applications

a technology of polymerization and oilfield, applied in the direction of fluid removal, wellbore/well accessories, chemistry apparatus and processes, etc., can solve the problems of coiled tubing or surface equipment, reducing the concentration of solids and the velocity of slurry pumping, and difficult control of solid placemen

Inactive Publication Date: 2012-10-25
SCHLUMBERGER TECH CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0005]One embodiment of the invention is a method of downhole treatment that includes pumping a fluid containing a polymerizable monomer downhole, initiating downhole polymerization, and allowing decomposition of the resulting polymer under downhole conditions. The monomer contains at least two polymerizable chemical groups and one or more degradable chemical groups and, optionally, one or more water-soluble groups linking the polymerizable...

Problems solved by technology

There are several problems in common for most of the applications here.
First of all, pumping of solids increases the risk of bridging and plugging in the wellbore, fracture, coiled tubing or surface equipment.
Second, there are always limitations on the concentrations of solids and on the velocity that can be attained during slurry pumping.
Third, placement of solids is difficult to control.
Fifth, if the polymer is soluble, the viscosity of the fluid may make pumping difficult and expensive.
All of the methods mentioned above for downhole polymerization assume permanent polymer placement, and application of the methods is limited to situations in which irreversible polymer placement is acceptable.

Method used

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  • Synthesis of Degradable Polymers Downhole for Oilfield Applications
  • Synthesis of Degradable Polymers Downhole for Oilfield Applications
  • Synthesis of Degradable Polymers Downhole for Oilfield Applications

Examples

Experimental program
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Effect test

example 1

[0057]It is well known that methacrylates cannot undergo thermal self-initiation of polymerization. Thus, for the polymerization of these monomers, radical polymerization initiators were employed. The number of polymeric chains in the polymerization is in direct proportion to the initial concentration of initiator. As polymerization proceeds up to a monomer conversion of 100%, then for a given polymer concentration, the larger the initial initiator concentration, the larger the number of growing polymer radicals that will be formed and be able to grow; thus there is a smaller number of monomeric units in each polymer chain. Thus, by varying the initiator / polymer concentration ratio, one can control the polymer molecular weight, and therefore the ease of polymer hydrolysis.

[0058]Polymerization of M1 in the presence of 10% of ammonium persulfate as the initiator was performed by the standard procedure described above, yielding white flakes of dry polymer. Hydrolysis of the polymer was...

example 2

[0059]Samples containing 0.5 M monomer in 5 ml of water were prepared with double the critical micelle concentration of surfactant (0.015 M for SDS and 0.007 M for TTAB) and treated with an Ika-Werke T 10 basic emulsifier for 5 minutes. The stability of the emulsions vs. time was checked; the results are sown in Table 1:

TABLE 1M1M2M4timeSDSTTABSDSTTABSDSTTAB5minStableStableStableStableStableStable10minStableStableStableStableStableStable20minStableStableAA——30min————BB1hourBBBBBB2hoursBBBBCB5hours————CB6hours————D24hoursEFCGGGA: White precipitate formed as emulsion begins to separate and disappears after mixing; emulsion was white.B: White precipitate which disappeared after mixing; solution was white.C: White precipitate which disappeared after mixing; solution was transparent.D: Emulsion nearly completely separated.E: Emulsion started to separate.F: Emulsion stared to separate; less stable than E (with SDS).G: White precipitate which disappeared after mixing; solution was transpar...

example 3

[0060]Emulsion polymerization experiments were carried out as follows: Samples containing 0.5 M monomer in 5 ml of de-ionized water were prepared with double the critical micelle concentration of surfactant (0.015 M (0.0217 g / 5 ml) for SDS and 0.007 M 0.0118 g / 5 ml) for TTAB). The mixture was stirred with an emulsifier for 5 mm. Ammonium persulfate initiator (2.5 10−3 mol / l (0.0029 g / 5 ml)) was added. The mixture was degassed by argon bubbling for 10 min and then heated in an oil bath to 60° C. for about 10 min to about 7 hours, depending on the monomer. The polymers obtained were dried at 100° C. The results are shown in Table 2.

TABLE 2M1M2M4SDSTTABSDSTTABSDSTTABTime of polymerization556.56.5Rapid*Rapid*hourshourshourshoursPhysicalClottedClottedCloudyCloudyCloudyCloudystate ofwhitewhitesolu-solution withsolu-solutionthepolymerpolymertionmaterialtionwithpolymerinsoluble,glass-in waterlikedropletsparticles*Mixture polymerized during bubbling of argon in less than 5 min.

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Abstract

A method is given for polymerizing monomers downhole to create well treatment polymers. The monomers each contain two polymerizable groups and a degradable group or groups which allow the polymer to degrade under downhole conditions, for example by hydrolysis. Polymerization downhole allows easier, more precise, placement of polymer. Polymer obtained from monomers pumped downhole may be used, for example, for fluid diversion plugs, isolation plugs, formation consolidation, flowback control, and fluid loss control. Synthesized polymer may form gels, films, solids or other structure in treated wellbores, fractures, and / or formations. After the desired effect is achieved, the deposited polymer degrades and the polymer degradation products dissolve, leaving the wellbore, fracture and / or formation clean, with no damage that might have decreased fluid flow.

Description

BACKGROUND OF THE INVENTION[0001]This invention relates to well completion, stimulation and remediation. More specifically, it relates to a method of polymerization of monomers downhole to create responsive polymer structures to provide a temporary or reversible treatment in a wellbore or in a fracture. The method includes irreversible polymerization of monomers under downhole conditions. The resulting polymer slowly degrades after it has performed its function, such as fluid diversion, wellbore isolation, proppant aggregation, formation consolidation, and fluid loss prevention.[0002]Degradable polymers have found many uses in the oilfield. As non-limiting examples: They may be used as diverting or isolating agents, for example in the form of ball-sealers, polymer fibers, flakes, and fine powders, and as a coating on proppant particles. They have been delivered downhole in the discontinuous (internal) phase of emulsions. They have also been used as acid precursors, and fluid loss ad...

Claims

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Application Information

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IPC IPC(8): E21B43/25
CPCC09K8/508C09K8/68C09K8/887C09K8/88C09K8/805
Inventor KHLESTKIN, VADIM KAMIL'EVICH
Owner SCHLUMBERGER TECH CORP
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