Diagnosis Of Leakage Loss Of Drilling And Completion Fluids In Horizontal Wells In Tight Sandstone Reservoirs

Horizontal well technology is one of the key technologies to exploit tight sandstone reservoir. In tight sandstone oil reservoir, the development of natural fractures is the main channel of hydrocarbon migration. When the horizontal well is drilled into the reservoir, the drilling and completion fluids have a large contact area and long contact time with the formation. Leading to a high probability of the occurrence of mud lose. If mud lose accident treatment is not timely, a large amount of drilling and completion fluids will quickly invade the formation under the pressure of the drilling, causing the damage of solid phase and liquid phase retention and the stress sensitivity of reservoir. And the development efficiency of oil reservoir was reduced finally.With the southern Erdos basin typical tight sandstone oil reservoir's Yanchang formation in Honghe oilfield as the research object, using indoor experiment and numerical simulation method, the characteristics of leaky layer leakage channel are analyzed. The dynamic damage experiment was carried out, and the prediction model of the invasion damage zone of the leakage damage is deduced, then the damage pattern of drilling and completion fluid loss in the horizontal well of the tight sandstone reservoir was constructed. Through calculation examples, the horizontal well leakage damage with solid/liquid space distribution and evolution was quantitatively described, which supplied the theoretical basis for drilling fluid system's optimization and improving the post acidification measures.The temporal and spatial distribution of the invasion damage zone of the fluid solid/fluid leakage loss in the horizontal well drilling completion fluid is defined. Based on the solute transport model, the drilling completion fluids' solid/liquid leakage loss of damage with predictive model was deduced. According to the results of field data and laboratory evaluation, the Honghe oilfield drilling and completion fluid solid/liquid leakage loss damage with temporal and spatial distribution was calculated through difference instance methods. The simulation results show that when the D90 in drilling and completion fluid is much smaller than the leakage layer dynamic fracture width, then the solid leakage loss of damage zone radius with solid phase particle size increases and increase, and the maximum value is 0.57m; liquid leakage invasion damage zone radius has a positive correlation with leakage pressure differential, leakage loss of layer crack width, leakage and the leakage amount. The radius was negatively correlated with the drilling and completion fluid viscosity, leakage loss of layer thickness, and the leakage loss of damage zone radius is mainly distributed in the 12-17m; leakage loss of damage flowback after the recovery rate of concentration distribution between 37.78%-57.41% and the maximum coefficient of epidermal is 12.26, resulting in serious damage in the leakage loss formation.The calculation method of the damage zone of drilling and completion fluid in tight sandstone is improved. According to the industry standard, design and develop the drilling and completion fluid dynamic damage experiments with the tight sandstone oil formation block rock samples of permeability between 0.1?1 mD; combined with the rock electricity experiment results, the inversion of water saturation changes of the block rock samples in the leakage invasion zone is conducted; the radius size of the drilling completion fluid filtrate in the block formation leakage damage zone would increase with the leakage positive differential pressure and formation permeability get larger. The experimental results show that the thickness of the solid phase cakes of drilling fluid in the block rock samples'end average at 2.2mm; drilling and completion fluid filtrate invasion damage zone's radius is mainly between 35.06?44.82cm. The epidermal coefficients change between 0.14-0.23. The maximum flowback recovery rate mainly distributed between the 48.92-71.82%, and the liquid phase retention in the reservoir block formation cause serious damage.The damage pattern of drilling and completion fluid loss in the horizontal well of the tight sandstone reservoir was constructed. Combined with horizontal well leakage damage characteristics, the drilling and completion fluid invasion damage zone's solid/liquid space distribution characteristics and leakage damage's multi-scale feature are analyzed; the wells that have mud leakage are classified according to their output, by considering about the porosity and permeability of the leakage loss wells'formation and these wells' production recovery curve, then the horizontal wells drilling completion fluid leakage loss damage model is constructed for different formation conditions of tight sandstone oil reservoirs; through the comprehensive analysis on the leakage process description and leakage damage removing process, the different leakage damage models of are applied in oil field.