The Study And Application Of Acidification System In Qianan Oil Field

Qianan daqingzi well is located in qianan daqingzi in Jilin province,The lithology of reservoir is composed of a large number of siltstone and a small amount of fine-grained sandstone.The main mineral composition of sandstone is quartz,feldspar and cuttings.The cement is mainly increased quartz,Illite/smectite mixed-layer,Illite,chlorite and carbonate minerals.The distribution of pore throat radius is 0.063-4μm on average,so the reservoir permeability is low and is vulnerable to fouling,pollution damage.In addition,the reservoir of wellbore area produces fouling seriously influenced by high salinity of formation water and water reinjection,which exacerbates the reservoir plugging further,It leading to yield decline of the wells finally and Invalid capacity.So we need new breakthroughs in acidizing plugging technology.According to the current situation of qianan daqingzi oil wells,we make it dear what is the main causes of pollution leading to yield decline of the wells,beginning with the study of reservoir damage mechanism in daqingzi well.By doing so,we provide a theoretical basis for acid formula and conform five kinds of basic acid formula system adaptable to physical properties of different reservoir and different wells preliminarily.In order to increase acid distribution further,to enhance efficiency of forming etching holes,thus to create deeper penetration of the acid,we start the research of selective oil external phase emulsified acid,potent acid and solution plugging technology under strong negative pressure.We have also entered field test and obtain a better effect of increasing oil.We have tested 90 wells in daqingzi oil field,73 wells are effective,the efficient is81.1%.Cumulative oil has been added to 3133 t by the end of November,2011.By now,the increasing oil for a single well is 34.8t on average and is effective eontiniously.