Research and development and application of PGA modified temporary plugging agent
The acid soluble temporary plugging agent is more damaging to the formation and difficult to solve,while the oil soluble is not suitable for the oil reservoir with high water content.The temperature of low-permeability reservoirs in Henan Oilfield is 50 to 120℃,and water flooding occurs quickly,and con-ventional water-soluble hydrolysis temperature of polylactic acid(PLA)and polyglycolic acid(PGA)is greater than 80℃,which cannot fully meet the needs of temporary plugging and fracturing of low permeabili-ty reservoirs.By combining the characteristics and temporary plugging principles of particulate PLA and PGA,catalysts and inhibitors are used to cause esterification reaction between polyglycolic acid and polylac-tic acid,generating a fusion of polyglycolic acid and polylactic acid.By adding nucleating agents and crys-tallization promoters,a modified polyglycolic acid temporary plugging agent can be obtained.The test results show that the modified polyglycolic acid temporary plugging agent has the solubility and temporary plugging strength of conventional polyglycolic acid temporary plugging agent at 50～120℃.When the total dosage of polyglycolic acid modified temporary blocking agent reaches 18%,and the dosage of coarse and fine tempo-rary blocking agents is close to 1∶1,the temporary blocking strength is greater than 40 MPa,and the tem-porary blocking performance is good.In the field test of 7 wells,after adding temporary plugging agent,the maximum construction pressure of single well increased by 6.1 MPa,the daily oil increase was 5.3 t,and an obvious oil increase effect has been achieved.
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