| Since the middle of the twentieth century, with the rapid development of world economy, the demand for oil and other energy has risen sharply, thus the amount of oil exploitation increased rapidly. With the increase in the number of drilling, blowout out of control accident sometimes occurs in the process of drilling, has become the biggest threat to the drilling safety factors. Wellhead blowout preventer has been widely used in drilling construction. In order to prevent the blowout from the source near the source, downhole annulus blowout preventer arises at the historic moment. The downhole annulus blowout prevention device is a well controlled tool which is used to prevent well blowout during downhole drilling. The equipment is installed between the drill pipes. The main role of downhole annular blowout preventer is is to prevent the liquid flow from the ring to the wellhead when the wells surge or blow up, to prevent the occurrence of blowout out of control. Rubber cylinders are the main downhole annulus BOP sealing element; the sealing performance will directly determine whether the downhole annular BOP can work. In order to improve the downhole annulus BOP sealing performance, make it play a good role on preventing blowout out of control, the study of downhole annulus BOP rubber cylinder sealing performance is very important. This paper studies downhole annular blowout preventer compression type rubber cylinder sealing performance.In this paper, based on the FPQ-178type downhole blowout preventer rubber cylinders as an example, using a flexible sealing theory to analyze the forces at work in the plastic tube, based on the factors affecting the downhole annular BOP rubber cylinders sealing performance is analyzed. Through the use of cylinder rubber material analysis, evaluation of the mechanical behavior of flexible sealing methods was studied. And on the basis of performance factors of influence on the sealing rubber ring, combined with the actual situation of underground air defense preventer is put forward to evaluate the method of sealing performance evaluation of underground ring air defense preventer rubber tube.Using the finite element analysis method, the various factors influencing the sealing performance of the adhesive are analyzed in the simulation. Get the influences of the thickness, length, friction factor, loading cones and rubber hardness of the plastic tube sealing performance. And analyzes the compression cones wellbore casing and sealing performance in the borehole wall. Put forward new outburst prevention device, and makes a comparison with the sealing property of the non outburst prevention device of rubber cylinder. Through the above analysis, it is concluded that the degree of various factors that affect the sealing performance of the adhesive, so as to improve sealing performance downhole annular BOP provides a theoretical basis.Based on the working actual situation of downhole annular BOP, rubber cylinders need to achieve a greater amount of expansion and contact stress, presented the new rubber cylinder for steel tape and rubber compound. Structure of steel strip has been optimized, and using the finite element analysis software, the composite sealing property of rubber tube under different conditions was studied. Obtained increased load packer cones can effectively increase the contact stress; contact stress adhesive tube is much larger than the same operating conditions, such as non-adhesive rubber cylinders conclusions.Through the annulus BOP rubber cylinders sealing performance analysis, the following ways can effectively increase the sealing performance of cones:1. Select the appropriate thickness and length of the plastic tube;2, two-way plastic tube loading packer load;3, increasing effective conflict prevention device;4, under construction permitting increased load packer;5, Using compound rubber cylinders, etc. |
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