Micro-fractures are developed in volcanic layers of Cretaceous Yingcheng Fm in the deep part of Xujiaweizi fault depression,Songliao Basin.In the process of well drilling,various complex problems happen,such as boreho...Micro-fractures are developed in volcanic layers of Cretaceous Yingcheng Fm in the deep part of Xujiaweizi fault depression,Songliao Basin.In the process of well drilling,various complex problems happen,such as borehole wall slabbing and collapse and serious fluid leakage.Based on conventional drilling fluid plugging evaluation methods,the real situations cannot be presented accurately,especially in fracture feature simulation and plugging effect evaluation.Therefore,a specific micro-fracture plugging evaluation method was put forward especially for high-temperature deep wells in the paper.It is a new type of micro-fracture core model with the fracture apertures in the range of 1-50 mm.It is made of aluminosilicate that is compositionally close to natural rocks.It is good in repeatability with fracture-surface roughness,pore development and fracture-surface morphology close to natural fractures.Obviously,this new model makes up for the deficiencies of the conventional methods.A new micro-fracture plugging evaluation instrument was independently designed with operating temperature of 200℃ and operating pressure of 3.5-5.0 MPa.It can be used to simulate the flow regime of downhole operating fluids,with the advantages of low drilling fluid consumption,convenient operation and low cost.The plugging capacity of the organo-silicone drilling fluid system was evaluated by using this instrument.It is shown that the grain size distribution of the drilling fluid is improved and its anti-collapse capacity is enhanced.Based on the field test in Well XSP-3,the safe drilling problems in volcanic layers with developed micro-fractures are effectively solved by using the drilling fluid formula which is optimized by means of this evaluation method.And the safe drilling is guaranteed in the deep fractured formations in this area.展开更多
In view of the fact that most of the filter media of existing plugging evaluation instruments use steel plates or steel balls, which cannot truly simulate the characteristics of the formation, a new type of TL-1 high ...In view of the fact that most of the filter media of existing plugging evaluation instruments use steel plates or steel balls, which cannot truly simulate the characteristics of the formation, a new type of TL-1 high temperature and high pressure plugging instrument has been developed. The filter medium of the instrument is the natural stone with different cracks and quartz sand beds with different particle sizes, which can better simulate the adsorption and hang-up effect of the formation on the plugging agent. It is possible to evaluate the plugging effect, pressure-bearing capacity and return pressure of the plugging slurry for different cracks and sand beds of different sizes under different temperatures and pressures. Using new and old instruments to evaluate the plugging effect of the same plugging slurry, it is found that the plugging effect is different from the distribution of the plugging material on the crack surface, the plugging effect and the pressure bearing capacity. The instrument is stable and reliable in operation and simple in operation. It is a new instrument for conducting research on anti-leakage plugging materials and anti-leakage plugging drilling fluid systems.展开更多
基金Project supported by CNPC Scientific Research and Technical Development Project“Research and Application of Supporting Drilling/Completion Techniques for Wells Treated with Special Technologies”(Grant No.2013T-0308-001).
文摘Micro-fractures are developed in volcanic layers of Cretaceous Yingcheng Fm in the deep part of Xujiaweizi fault depression,Songliao Basin.In the process of well drilling,various complex problems happen,such as borehole wall slabbing and collapse and serious fluid leakage.Based on conventional drilling fluid plugging evaluation methods,the real situations cannot be presented accurately,especially in fracture feature simulation and plugging effect evaluation.Therefore,a specific micro-fracture plugging evaluation method was put forward especially for high-temperature deep wells in the paper.It is a new type of micro-fracture core model with the fracture apertures in the range of 1-50 mm.It is made of aluminosilicate that is compositionally close to natural rocks.It is good in repeatability with fracture-surface roughness,pore development and fracture-surface morphology close to natural fractures.Obviously,this new model makes up for the deficiencies of the conventional methods.A new micro-fracture plugging evaluation instrument was independently designed with operating temperature of 200℃ and operating pressure of 3.5-5.0 MPa.It can be used to simulate the flow regime of downhole operating fluids,with the advantages of low drilling fluid consumption,convenient operation and low cost.The plugging capacity of the organo-silicone drilling fluid system was evaluated by using this instrument.It is shown that the grain size distribution of the drilling fluid is improved and its anti-collapse capacity is enhanced.Based on the field test in Well XSP-3,the safe drilling problems in volcanic layers with developed micro-fractures are effectively solved by using the drilling fluid formula which is optimized by means of this evaluation method.And the safe drilling is guaranteed in the deep fractured formations in this area.
文摘In view of the fact that most of the filter media of existing plugging evaluation instruments use steel plates or steel balls, which cannot truly simulate the characteristics of the formation, a new type of TL-1 high temperature and high pressure plugging instrument has been developed. The filter medium of the instrument is the natural stone with different cracks and quartz sand beds with different particle sizes, which can better simulate the adsorption and hang-up effect of the formation on the plugging agent. It is possible to evaluate the plugging effect, pressure-bearing capacity and return pressure of the plugging slurry for different cracks and sand beds of different sizes under different temperatures and pressures. Using new and old instruments to evaluate the plugging effect of the same plugging slurry, it is found that the plugging effect is different from the distribution of the plugging material on the crack surface, the plugging effect and the pressure bearing capacity. The instrument is stable and reliable in operation and simple in operation. It is a new instrument for conducting research on anti-leakage plugging materials and anti-leakage plugging drilling fluid systems.
