Research And Application Of Drilling Fluid Filtration Technology For Horizontal Wells In Dagang Oilfield

While drilling reservoirs, due to positive pressure and capillary force, the solid phase in the drilling fluid invades and blocks the reservoir pore throat, and meanwhile the liquid phase reacts with formation rock and fluid, breaking the original reservoir balance, which will induce potential reservoir damage and make permeability decrease. Since the horizontal well development has its particularity (chanllenging drilling process, larger contact area, long contact time, screen completions of production wells through long sections, and large drainage area to enhance well production), formation damages are generally more serious in horizontal wells.This academic dissertation is based on Dagang oilfield drilling fluids used in recent years as the main object of study. The original mud cake removing technology and the shortcomings of the original drilling fluid system are analyzed through the experiments. On the basis of GC series of horizontal well drilling fluid, filter cake removing research and developing evaluation techniques were carried out.Three horizontal wells drilling fluid filter cake removing technology has been researched and developmented. After the core is treated by the system, permeability recovery rate reaches more than 91%. The system functions using a variety of components combining with each other to form a compound effect of the working fluid manner, improving the effect while reducing the kinds of working fluid. The system reduces the cost of field application basis. Its main performance index was far more than the active system (cleaning, corrosion, broken plastic), assisting performance indicators (anti-swelling, steady iron, cleanup, corrosion) is also in the forefront, achieving the desired purpose. Also, the system has a response rate fast, simple construction process, and short construction time.Completing pilot tested 14 wells, and the test wells success rate reaches 100% without a leakage or other accident. The pump pressure decreased and the displacement gradually increased, indicating that with the progress of construction, drilling fluids and drilling fluid in the wellbore and the cake near the wall at the blockage releasing back out of the flow channel is clear. After the commissioning of the liquid sufficient amount of fluid level is high, the yield reached or exceeded with a basic level of production. The production rate index per meter for compaison wells and testing wells increased by an average of 94.2% and 53.8%, respectively.