Mechanism Analysis Of CT During Horizontal Annular-delivery Sand Fracturing

Annular sand, tubing into the equilibrium solution of coiled tubing annular sandfracturing technology to solve the hydraulic fracturing process nozzle low life, constructioncapacity is small shortcomings, is to require large discharge, large amount of liquid,continuous multistage fracturing features of "network fracturing technology" and "bodybacklog of splitting technique" for the implementation of the new approach. However, thecoiled tubing annular sand fracturing technology currently has the following problems: largecapacity injection fracturing fluid is easy to cause the wellbore temperature change greatly,resulting in fluid flow friction complex changes, changes can be determined by the groundpressure reflect the bottom hole pressure; at the same time in the process of fracturing packerunder larger piston force there exists the possibility of moving or breaking, directly affect theaccurate positioning of fracturing and fracturing construction safety. In view of the aboveproblems, this paper carried out the following research:(1) through the accurate calculation of fracturing fluid temperature fracturing process,based on the experimental results of flow characteristics of temperature and sand ratio on thefracturing fluid, the annulus fracturing fluid flow friction calculation method of segmentation,accurate calculation of different factors (different displacement, deep well, fracturing fluiddensity) flow friction of fracturing fluid, and based on this chart making annulus and tubingground pressure oil sleeve pressing process and the bottom hole pressure.(2) for the mechanics analysis of coiled tubing annular sand fracturing process, a set ofdifferential equations of deformation of coiled tubing. And according to the judgment of thecoiled tubing buckling deformation differential equation, analysis of downhole condition ofcoiled tubing. Establishment of annulus fracturing process of coiled tubing load and stresscalculation model, and the difference of coiled tubing load and the numerical calculationmodel of stress method.(3) using the force of the annulus fracturing process sealing packer rubber and casingbetween the contact stress is simulated by finite element software Ansys, get different throttlepressure of packer rubber tube anchor. Combined with the results of field test, theestablishment of different throttle nozzle pressure difference hydraulic anchor forcecalculation model.(4) in the annulus fracturing process of coiled tubing end axial force and anchoring forceequal principle, process of establishing fracturing packer does not occur to ensure mobilecoiled tubing critical injection rate calculation model. Then the one annulus fracturinghorizontal well as examples, discharge and stress analysis of coiled tubing critical injection onthe well.Therefore, the accurate calculation of bottomhole pressure annulus fracturing process,establish the relationship chart of ground pressure and bottom hole pressure, ensure the packerdoes not move the coiled tubing rehydration capacity as well as through the coiled tubing stress analysis was carried out on pressure field ground construction, convenient choice, toimprove the accuracy of ring empty sand fracturing fixed-point construction and ensure thesafety of the fracturing pipe column construction has important significance.