Polyurethane for Oil Well Refracking

Patent Title: METHODS AND MATERIALS FOR REFRACTURING A PARTIALLY DEPLETED OIL AND GAS WELL

Number/Link: US2018/0346786

Applicant/Assignee:  Covestro

Publication Date: 6 December 2018

“Gist”: Use of low-reactive, low-viscosity PU systems for oil well sealing

Why it is interesting: It is known that partially depleted fracking wells can be “re-fractured” to increase production. Prior to this operation former perforations in the well casing need to be sealed to prevent furthering of existing fractures, by using a chemical “diverting agent”.  According to this invention, the diverting agent can be a polyurethane system with a long potlife and relatively low viscosity, which is prepared from an unblocked hexamethylene diisocyanate and a polypropyleneoxide triol which is miscible with the isocyanate. In the examples an allophanate-modified HDI is used together with a 450-molecular weight PO triol and a delayed-action tert amine catalyst. The system does not de-mix and has a gel time ranging from 30 to more than 1000 minutes.

refracking

Sealing of fracking well

 

 

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Fuel Resistant Polyurea

Title: POLYUREA COMPOSITIONS AND METHODS OF USE

 Number/Link: US20140171587

Applicant/Assignee: PRC DESOTO

Publication date: 19-06-2014 (priority PCT)

Gist”: Sulfur-containing polyformal polyols are prepolymerized with aliphatic diisocyanates and then cured with aromatic amines.

Why it is interesting: Sulfur-containing polyformal polyols are prepared from thiodiglycol and paraformaldehyde using acidic catalysis.  The polyols are then reacted with 4,4′-dicylcohexyl diisocyanate (H12MDI) to form a prepolymer which is subsequently cured with an aromatic amine like dimethylthiotoluenediamine. The resulting material is water and fuel resistant and can be used as a sealant in the aerospace industry.

H12MDI-thiodiglycol-polyformal adduct

H12MDI-thiodiglycol-polyformal adduct