Preparation And Evaluation Of Composite Water Shutoff Profile Control Agent

With the exploitation of oilfields in the middle and late stages,most oilfields use water flooding in the middle and late stages,resulting in an increase in oil injection in the oilfield.Due to the non-uniformity of the oil layer geology,the oilfield is prone to "waterlogging"and needs to block the "water raft".Change the water absorption profile.The water shutoff and profile control technology of medium and high temperature reservoirs has gradually developed and matured,and the development of water shutoff and profile control technology for medium and low temperature reservoirs is slow,especially the low temperature oil storage and profile control technology.The low temperature water shutoff and profile control technology has always been a technical problem.In this paper,the middle temperature low temperature and low salinity reservoir bottom layer was developed,and the medium temperature composite gel water shutoff profile control system and low temperature water shutoff profile control system were developed to obtain the superior gel ratio.The effects of various factors on the gel properties were investigated.Performance evaluation of the gel under optimal conditions.In this study,gel strength and gelation time were evaluated as evaluation indexes.The distribution ratio of each group of medium temperature composite gel system was selected by single factor experiment.The concentration of inorganic polymer was 6%,the concentration of crosslinking regulator was 2%,and organic polymer.The mass concentration was 0.3%,and the mass concentration of the cross-linking agent was 0.3%.In order to study the effect of various factors on gel strength,orthogonal design was carried out.The results of orthogonal test showed that the influence of various factors on gel strength:crosslinker>crosslinking regulator>organic polymer>inorganic polymer.The optimal gel formula:the inorganic polymer mass concentration is 8%,the crosslinking regulator has a mass concentration of 4%,the organic polymer mass concentration is 0.3%,the crosslinker mass concentration is 0.3%,and the temperature is 60-90?;The distribution ratio of each group of low temperature composite water shutoff profile control system was prepared,the organic polymer mass concentration was 0.2%,the inorganic polymer mass concentration was 12%,the crosslinker mass concentration was 0.3%,the catalyst mass concentration was 0.05%,and the adaptation temperature was 25-50?.The gel application performance was investigated.The results show that the medium-low temperature gel system is suitable for mineralization less than 10000mg/1.The shear resistance evaluation shows that the gel system has good shear resistance.The gel is placed in a water bath for 40 days.The water content is less than 35%and has good thermal stability.The structure properties of the gel were investigated.The internal structure of the gel was observed by scanning electron microscopy,which indicated that the gel structur exhibited a three-dimensional network structure.Thermogravimetric analysis showed that the gel structure temperature was above 300?.Investigate the gel plugging performance,simulate the core experiment with sand filling tube,and determine the gel plugging rate.The experiment shows that the two plugging and profile control systems are blocked more than 95%,and the medium temperature composite profile control system breaks through the pressure gradient 5.163MPa/m.The composite gel profile control system broke through the pressure gradient of 3.93 MPa/m,indicating that the two profile control systems have good plugging properties and strong pressure resistance.