Study On Well Control Technology For Cracking Of Cracked Reservoir

Since the narrow safety density window of drilling fluid and the gravity displacement between drilling fluid and formation fluid, well kick and lost circulation always happen at the same time when drilling fractured reservoir. The main solution is using bullheading push the gas back into the reservoir. However, it might cause inevitably damage of the reservoir as well as rise of the reservoir pressure which could lead to a vicious circle, so the original well control technology needs to be improved.The solution of this situation in fractured reservoir in this thesis is plugging first and then killing the well. Research mainly includes:1) The difference between porous reservoir and naturally fractured reservoir has been proved by analog calculate their safe density window;2) Bullheading and the problems it may cause when dealing with complicated well control issues in naturally fractured reservoir has been analyzed and different well control technology for different type of fractured reservoir has been proposed, which could be concluded as a widely applicable well control method of naturally fractured reservoir;3) The characteristics and the ability of bearing pressure of special gel (ZND) have been researched and the executive parameter and the design flow of the well control technology of gel slug packer have been designed;4) The feasibility of implement the well control technology of fractured reservoir has been testified by applying it in7wells in Tazhong area.The results show that the advanced well control technology of fractured reservoir applied well in the fields. This technology could not only reduce the risks of drilling but also increased productivity of an individual well, which may play an important role in well control in fractured reservoir.