Preparation method for fumaric acid pour point depressant for crude oil

A preparation method for a fumaric acid pour point depressant for crude oil, comprising the following steps:

• pre-polymerizing vinyl acetate and a first monomer having a weight ratio of (1-10):1 to obtain a first prepolymer with a degree of polymerization of 20-40;
• pre-polymerizing fumaric acid and a second monomer having a weight ratio of (10-50):1 to obtain a second prepolymer with a degree of polymerization of 18-50;
• and
• adding a third monomer to the second prepolymer, performing esterification for no more than 1 hour, then adding the first prepolymer and a fourth monomer, and performing polymerization for at least 3 hours to obtain the fumaric acid pour point depressant for crude oil;
• the first prepolymer, the second prepolymer, the third monomer and the fourth monomer have a weight ratio of (5-25):(10-80):(5-20):(2-25);
• the first monomer is a mixture of N-vinylpyrrolidone and 2-(N-acryloyloxy)ethylpyrrolidone;
• and the N-vinylpyrrolidone and the 2-(N-acryloyloxy)ethylpyrrolidone have a weight ratio of (1-6):1;
• the second monomer is a mixture of allyl polyether and allyl alcohol polyether;
• and the allyl polyether and the allyl alcohol polyether have a weight ratio of 1:(10-35);
• the third monomer is a mixture of tetradecanol, hexadecanol, octadecanol and eicosanol;
• and the tetradecanol, the hexadecanol, the octadecanol and the eicosanol have a weight ratio of (1-10):1:(1-5):(1-5);
• the fourth monomer is a mixture of acrylamide and N-(hydroxymethyl)acrylamide;
• and the acrylamide and the N-(hydroxymethyl)acrylamide have a weight ratio of (1-15):1.