Viscoelastic Surfactant Self-shunt Acid Developed And Acidification Model

In the process of matrix acidizing,happened in the carbonate reservoir,when the acidcomes into the reservoir with high injectability,it will give birth to a flow channel injectivityalso called wormhole which possess the high-flow capability.So injectivity willincrease,whereas the other layers remain undone. In order to gain an effective acidizing,it iseaaential to distribute the reaction acid effectively.The acid reacts in the porose and channelsamong the carbonate matrix,which will greatly increase the permeability. So the diversion incarbonate rocks is more difficult than in the sandstone.For exsample,most oil resin can't beapplied into carbonate reservoir,because the resin particles fail to flug up the floeing spacecreated by acid.And other solid objects,such as naphthalene/albocarbon are restricted inapplication.The solid grains of fitness size are adopted into use because they couldeffectively get through the gravel zones and perforation tunnels.But there is also oneproblem that they would be absorpted on the surface of the rocks,grains of unfitness size cancause depth invasion,which will be harmful to the formation and bring more difficulties inflowback.foam and polymer gel is limited by temperature and the differeness inpermeabiliry,furthermore,in the high permeability formation there are a great number ofsuch diverting agents leakoff and would cause damage.These mentioned above are adversein the carbonate matrix acidizing.Viscoelastic surfactant self-diverting acid(VES-SDA) is a brand new technology recently developed abroad.It is fit for carbonate diversion acidizing.In the process of acid reaction,it can let the acid come to the formation,which need stimulation. It enjoy so manyadwantages,such as wonderful diverting,causing no damage,easy flowback,reguiring few addition agents.There is a good prospect for its application. Oversea companies adop this techniqu successfully.It is still of very hot research avroad. But in china,this research areais blank.In this dissertation,first studied the diverting process and explored the gelled mechanism of viscoelastic surfactant self-diverting acid,and get to know what kind of surfactants could meet the requirements of viscoelastic surfactant self-diverting acid.Based on the understanding of the mechanism, this thesis composed the new main agents of VES-SDA in the laboratory,and optimize the synthesis conditions for the main agents by orthogonality experiment.This thesis got to know the rheological characterization of VES-SDA and the properties of the acid system by experiments. These knowledge would be essential to guid the application of VES-SDA at the scene.This thesis analysis the diversion mechanism of VES-SDA and simulate the diverting process of VES-SDA,it is required to ascertain the flow and concentration of VES-SDA in the matrixes andwormholes. In the acidizing, the growing wormhole is influenced by the flow,which brings some changes in the pressure field distribution and control the wall surface of wormhole and acid fluid loss,and vice versa.This thesis established and simultaneously calculate the wormhole developing model in the process of matrix acidizing and acid three-dimentional flowing reaction model.