Theoretical And Parameters Research On Processing Technique Of Adjacent-well Stratum By Abrasive Jet

The technology of abrasive jet deposing near well stratum is a new and high technology which was developed in recent years to restore and improve the permeability near well stratum, increase production and injection and raise the oil output. We have performed the experiment on the spot and applied this technology on 200 more wells in Daqing, Shengli, Liaohe, Henan oil field and so on, and have achieved the good results. This thesis does theoretical research on the main scientific problems in the technology.First, the block caused by fluid production, solid particles and plastic precipitation which are produced in the process of drilling, completion, silo operating, long-term oil production and injection water increases the stratum stress around the wells, leads it to redistribute, reduces the pore slit and destroys the near well stratum. Stress redistribution and the slit reducing can be respectively viewed as the effluent seepage of movable boundary and compressive frame. We can get the changeable law and influence scope of permeability near well stratum which provides a theoretical basis for construction technology.Abrasive jet is solid-liquid two-phase fluid. In the constitution of abrasive jet, the quality of sand is 5%, and volume is 3%comparing with the same quality and volume water, particles are far less than it. Thus the interaction between particles and fluid and between particles can be ignored, so sand and water, the two-phase fluid can be simplified as the equivalent one-phase fluid to find solutions according to the ordinary one-phase fluid mechanics. Since the particles interaction can be ignored, solid as Newtonian viscosity fluid. Considering the speed of jet is high (generally is turbulence flow) by applying slip-stick model, ignoring the gravity, and regarding fluid flow as incompressible stationary flow, we get the stationary equivalent turbulence differential equation under the hypothesis conditions as remarked above. According to the principle of common fluid mechanics, we can find the solutions of equivalent fluid by using singular perturbation. That is, the differential equation of free turbulence jet boundary layer of two-phase fluid pore or differential equation of pore free turbulence abrasive jet.By using similarity solution and momentum integral method to find the solution of differential equation of abrasive jet as mentioned above, we can conclude the law that axial flow speed and the jet radius change along the axial line which provides a basis for analyzing that abrasive jet impacts on material and the surface of target.The research shows, the destruction of adapting pipes influenced by abrasive jet is mainly that abrasive jet imposes pulse loading on materials by continual rapid impact, but the continual impact of water plays the role in the process of material destruction. So jet stress is able to be reduced significantly for cutting. Contact force generated by particles imposing on the surface of material can form contact shear stress and radial tensile stress. Under the influence of jet, rock layer's destruction is the abrupt cut-off of block which is produced by jet when it contacts with rock layer, with the production of hydraulic pressure which spreads to rock layer in the form of wave named loading waves. When hydraulic pressure instantly disappears, unloading waves, because of producing tensile stress, the rock layer is destructed.The jet which plays a role on the internal surface of metal adapting pipe can be seen as free submerged jet. Abrasive particles impact on the metal adapting pipe at the same rate of the equivalent fluid jet. Generally, metal material's pull-resistant strength is the equal to the compressive strength, but both of them are far stronger than shear strength. So contact shear stress generated by abrasive particles impacting on the surface of the pipes is stronger than contact shear strength and results to destruction. According to the contact theory of Elastic Mechanics, establish the cutting formulation of abrasive jet of metal adapting pipe. Containing hydraulic, abrasive, cutting and adapting pipe material parameters which can be used to study the parameter changes which influence the abrasive jet cutting the pipes and confirm the injury cutting technology parameter. Abrasive jet cutting has certain reference significance for other metal materials.Under wells, rock cutting continues to impact the rocks in the slits which are formed in the process of abrasive jet cutting the metal adapting pipes and in the slits of having cut rock layer. Influenced not only by the notch of metal adapting pipes, but also by the wall of rock layer on its bottom and both sides, efflux flow can not be seen as free jet. Under that condition, we can establish the differential equation of abrasive fluid flow by using dimensional analysis method to find the solutions, we can get the changeable law that the largest axial-oriented flow speed of jet change along the jet orientation and the law of distribution that jet half width is along jet-orientation. According to Rock Mechanics, the rock's pull resistant strength is far less than compressive strength and shear strength, at the same time, according to the theory of stress waves in Elastic Plastic Mechanics, we can know the largest pull stress produced by unloading waves. When the largest pull stress exceeds the rock's pull-resistant strength, the rocks will be damaged, at the same time, we can get the equation of abrasive jet cutting rocks including hydraulic, abrasive, and cutting parameters and the physical qualities of rocks. By using the equation, the parameter's influence on the cutting can be shown. The equation also provides the basis to determine the parameters of cutting technology for depositing near well stratum.According to the ground imitative tests of the abrasive jet disposing near well stratum, we can find the results of the tests conform to the theoretical computational results established by this thesis, which can be utilized in practical project. Finally, the thesis discusses the selection and confirmation of cutting technology parameter of abrasive jet on the basis of established computational formulation of abrasive jet cutting metal adapting pipe and rock theory and the ground imitative tests.