Xinmin Ultra-low Permeability Reservoir Acidizing Technology Research And Application

The sandstone reservoir of Xinmin Oilfield is a typical low abundance and low permeability. The heterogeneity of reservoir is serious and the single well production is low. In the process of oilfield development, the phenomenon of reservoir pollution was quite common and restricted the oil well productivity seriously, which influenced the oilfield development. As one of main oilfield development measures, acid treat is able to dissolve the grains and impurities in the process of drilling, completion, well repair etc through flowing and reacting of acid among pore space and micro-fracture. It can dissolve the damage of formation permeability and ball out the flow matrix, then recover and improve well productivity.This paper analyzed geology situation of Xinmin oilfield. In order to study the reservoir damage mechanism of Xinmin oilfield, it evaluated velocity sensitivity, water sensitivity, salt sensitivity, acid sensitivity and alkali sensitivity of permeability and porosity of reservoir, it analyzed scaling situation, composition and its reason, and it researched production well blocking and scaling and some potential hazard like this. The results showed that the factors of damaging reservoir formation contained internal factor like reservoir rock, reservoir liquid and reservoir situation and external factors like man made measurements in operation process. In addition, Two acidizing formula systems suited for Xinmin oilfield were optimized by studying ultralow permeable acidizing system, emulsified acidizing system, strong acidizing system and screening of acid additive. They were emulsified acidizing system, which included preparing fluid containing0.5%surfactant,1.0%clay stabilizer,2.5%organic solvent, operation fluid containing3%0#diesel,8%hydrochloric acid,1%corrosion inhibitor,2%emulsifier agent,1%discharging aiding agent,1%ferrous stability, and subsequent fluid0.2%demulsifier. And the other was strong acidizing formula system, which included preparing fluid containing1.5%emulsifier agent,3.5%surfactant,1.0%strong effect agent, operation fluid containing3.5%sulphamic acid,0.2%demulsifier agent,1.5%corrosion inhibitor,0.5%clay stabilizer,0.5%ferrous stability,0.5%discharging aiding agent, and subsequent fluid water. Aiming at the two systems, it determined and optimized the acidizing dosage, acidizing radius, interjection pressure, maximum pump injection displacement and injection technology. Finally, it proved that the production gain improved more than12%and increased economic benefit of whole oilfield through the laboratory analysis and field test research.