The Research Of Sand Control Technology By Expandable Pre-graved Screen

At present, the existing mechanical sand control methods are unsuitable to competent for sand control of oil field during middle and later oilfield development. It becomes one of key problems of oil field development to improve existing sand control technology and empolder new sand control methods.Combined the pre-grave packed screen and the expandable screen, the pre-graved screen expandable is developed, which includes threeparts: outer protective shell, gravel and inner sustentative slotted screen. The distinct merits of the pre-graved expandable screen are the one-off of gravel packing and expanding, small expandable force and little influence on other download equipments. And the expandable pre-graved screen will become on eof main sand control methods which has low cost and long service term. The inner sustentative slotted screen is the foremost part of the pre-graved expandable screen. Aiming at the current structures of inner sustentative slotted screen, the slotted screen with compound cavity is designed which has remarkable characteristic of narrow outside and capacious inside.It prolongs the sand control period, enlarges the indraft area of pump, and decreases the flow resistance which is furthersome for oil production.It is inevitable for the erosion of the inner sustentative slotted screen with compound cavity. Therefore, the erosion mechanism is studied through experimental simulation and lots of erosion velocity data with different parameters are gained. The erosion prediction model is built adopted BP method. Moreover, the service period forecastable model of inner sustentative slotted screen with compound cavity is built via the conversion between slot width and erosion velocity. The experimental results indicate that the erosion styles contain pitting-type,eploughing groove and slicing-style. And it appears one new style of ravine mark that pitting-type notch and eploughing groove notch connected together. Otherwise, the parameters of inner sustentative slotted screen with compound cavity are closely linked with closely linked with its strength and flow resistance.Aiming at the issues of complicated modeling and long calculational cycle and unsolved given problems, one mesh generation method with dividing the boundary unrestrictedly is put forward. Based on this method, the FEM special software for inner sustentative slotted screen with compound cavity is developed which has virtues such as simple modeling, small kernel and rapid calculational speed et al.. The relations between parameters of inner sustentative slotted screen with compound cavity and its strength and flow resistance are calculated via SFEM and Fluent. The strength forecastable model and flow resistance forecastable model are built through BPmethod.Based on the prediction model of strength, flow resistance and service period, the optimization design is applied on parameters of inner sustentative slotted screen with compound cavity through hybrid genetic algorithm method which changes the traditional method with experiential formulae. The inner sustentative slotted screen with compound cavity after optimized has merits low flow resistance, long service period and high strength which establishes the base for its popularize application.For improving the expandable ability of outside outer protective shell, the special structure is designed which has unequal radius along circumferential direction. The outer protective shell may realize small expanding force and large redeeming displacement which provides guidance for its field application. Moreover, the relation between parameters and expanding ability of outside outer protective shell is analyzed and its expandable theory is described through numerical analytical method.