Coated Fracking Proppants

Patent Title: AMIDE BASED COATING

 Number/Link: WO2017/213855

Applicant/Assignee:  Dow

Publication date: 14 December 2017

Gist”: Proppant particles are coated with polyamide based on isocyanate and carboxylic acids

Why it is interesting: Proppant particles are used in the hydraulic fracturing process to force open rock fissures to extract gas and oil – as discussed before in this blog. According to this invention the proppant particles are coated with a reacting mixture of a polyisocyanate (e.g. polymeric MDI) and polycarboxilic acids (e.g. a blend of citric acid and an acid-terminated polyether triol). Under the high pressure and temperature of the fracture, the coating will bond the proppant particles together, thus preventing flow-back of the proppant and the blocking of the well. The coating can contain additives to capture heavy metals like radium and sulfides like hydrogensulfide to reduce contamination of the fracture fluid.

citricacid

Citric acid

Polyurethane-Polyamides from Dimer Diacids

Title: A POLYOL BASED ON DIMER FATTY ACID RESIDUES AND THE CORRESPONDING POLYURETHANES

 Number/Link:WO2015/097433

Applicant/Assignee: Croda

Publication date: 2-07-2015

Gist”: Polyurethane/polyamide elastomers based on dimer diacids and long chain dicarboxylic acids

Why it is interesting: Polyurethane elastomers (and thermoplastic elastomers) based on dimer diacids or dimer diols are very hydrophobic and hydrolysis resistant but are relatively soft with lowish mechanical properties. According to this invention, using a blend of a dimer diacid (or -diol) and a (semi-) crystalline C17 to C32 dicarboxilic acid (or -diol) results in elastomers with greatly improved hardness and tensile strength while retaining flexibility and hydrolysis resistance. The C17 to C32 dicarboxylic acids can be prepared by a self-metathesis reaction of unsaturated fatty acid esters.  In the examples a C36 dimer diacid is used together with 1,18-octadodecanoic acid (prepared by metathesis from methyl oleate).  This is reacted ‘one shot’ with 4,4′ MDI and hexanediol or DEG, resulting in 85 shore A elastomers with high elongation and hydrolysis resistance.

A C36 dimer diacid

A C36 dimer diacid