Study And Development Of High Viscosity Polymer Gel Plugging Agent For High Temperature Fracture Reservoir

Oilfields used waterflood for exploration increasing sharply at present.And water flooding and water channeling increasing due to waterflood development.Therefore,how effectively control water in high-temperature,high-salt fracture reservoirs has become a difficult study.Relevant research has been carried out to solve this problem wordwide.However,a few water blocking agents with high temperature resistance,good injection performance and high pressure bearing capacity were development nowadays.In order to fill the technical blank of water shut off in high-temperature fractured reservoirs,this paper developed a high-viscosity blend gel hydrogel plugging agent.The development was based on the theory of gelation kinetics,combined with the characteristics and development status of high temperature fractured reservoirs,using inorganic composite intercalation technology,through changing the crosslinking mode and crosslinking structure to develop high viscous hydrogel plugging agent in high temperature fractured reservoir.And this paper provided a technical support for high temperature fractured reservoir exploration.The mainly completed works and corresponding research results of this article are as follows:(1)The system composition material optimization experiments were carried out by observing the preparation and gelation of each pre-selected material system.The apparent viscosity,gel strength,and adhesion performance of each initial solution were compared.A high-viscosity blended gel system was established.The system formulation was polymer Y5(2 wt%)+crosslinker S4(1 wt%～1.5 wt%)+ toughening material P5(5 wt%)+additive(0.02 wt%);And the screening system has good gel strength and adhesion performance.(2)The rheological properties of high-viscosity blended gel water-retaining agent for high-temperature fractured reservoirs were studied.The influences of composition concentration,gelation temperature and salinity on the gelation time and gelation performance of the high viscous gel were clarified.The polymer gels developed in this article have good salt resistance properties and maintain good gel performance for 120 days at 130℃.(3)DSC,XRD,SEM and viscoelastic heating tests were used to study the gelation mechanism and the blending mechanism of polymer gels.The polymer can effectively enter the layer of inorganic toughening materials and form a polymer gel water-blocking agent with high strength and good adhesion performance;the thermogravimetric analysis of the polymer gel shows that the thermal stability of the gel increases with the concentration of the cross-linking agent.What’s more,the weight loss peak temperature is 109℃ for a crosslinker system with a 1.5%trainer concentration.(4)The physical simulation experiment of fractured core is carried out,and the resistance coefficient of high viscous hydrogel plugging agent is between 235.3～139.7 in the range of fracture width 0.72mm～1.41mm.The drag coefficient decreases with the increase of the fracture width;Polymer gel has a good injection performance;For the core with a fracture width of 1.41mm to 0.72mm,the polymer gel breakthrough the pressure gradient up to 60.05MPa/m and 108.27 MPa/m.The high-viscosity blended gel developed in this paper has a good ability to fractures;the high-viscosity blend gel poccess good sealing performance that a plugging rate of 91.41%for cores with a width of 1.41mm;There are obvious residual gels after breakthrough of the simulated formation water,and good adhesion to the fracture wall.