Many oil fields producing waxy crude, face severe wax deposition problem in down hole tubulars and surface flow lines. Sometimes this problem is also encountered at the face of producing zone in the well bore region due to changes in temperature & pressure conditions. This problem frequently results in complete blockage of the crude passage and poses severe production problem. Conventional methods such as thermal, magnetic, mechanical scraping, solvent cleaning and chemical treatment etc. are not only cumbersome, costly and hazardous but provide only temporary respite. Two separate microbial systems, capable of mitigating the vexed problem of paraffin deposition in oil well tubulars and surface flow lines have been developed.
The microbial system for down hole tubular comprises of paraffin degrading bacterial (PDB) consortium named as PDS-10, nutrient supplements and growth enhancer. Laboratory studies showed significant reduction in pour point and flow behaviour of the crude. The process is effective up to 900C but maximum efficiency was observed at 550C. Field trial in 100 wells of different fields of Western & Eastern sector has shown that the treatment not only checked the paraffin deposition in all the treated wells but also improved oil production by 20-80 % in many wells. Most of the treated wells flowed without any wax deposition for 6-8 months after the treatment.
For flow assurance in surface flow lines bacterial consortium named as FIB-19, which shows high degree of wax degradation capability has been developed. The bacterial consortium is aerophilic, mesophilic and remains active upto 430C. Field trial in surface flow lines of twelve wells of Ahmedabad Asset was quite successful resulting in elimination of requirement of line flushing for considerable time along with reduction in pressure in the flow line. The average period of effectiveness of the jobs has been found to be around 4-5 months.