| The petroleum and natural gas is the important energy and strategic resources for the sustainable development of the national economy, the stability of social life and the national security. With the rapid development of China’s national economy, the demand for oil and gas resources grows dramatically and the contradiction between supply and demand is increasingly grim, which has become a bottleneck restricting the future development of the country. With the deepening of China’s oil and gas exploration and development, the focus of China’s oil and gas exploration and development in the future will be all kinds of "difficult to use" oil and gas resources and deep strata, deep-sea exploration and development of oil and gas resources. However, the oil and gas drilling and development in deep strata and deep-sea are faced with many challenges, especially the drilling safety and security. The chance of confronting with pressure-sensitive oil and gas well will increase in deep strata oil and gas drilling. Attaching great importance to the drilling safety, a series of measures to ensure the safety of the drilling at the expense of drilling efficiency are taken, however the uncontrolled blowout accident still can not avoid. For example, in the drilling process in China’s Sichuan yuanba gas field, because of the strata fracture development, the leakage and spray in the same layer and the narrow mud density window, the risk of well control greatly increases, even lead to uncontrolled blowout accident. The traditional process of well control and well control equipment has been unable to meet the drilling safety requirements in sensitivity strata drilling. Therefore, the development of a new set of well control technology and equipment to adapt to the drilling safety in sensitivity strata has become a development direction of the well control study. The underground blowout preventer system as a new well control system can be more "early discovery, early control, quickly and easily snubbing" than traditional well control technology. With the increasing of the sensitivity strata drilling in recent years, the underground blowout preventer system gradually become a hot research topic in well control.In this paper, on the basis of comprehensive investigation of the existing domestic and international well control technology, equipment and downhole communication technology, the advantages and disadvantages of a variety of well control equipment and well control process and underground communications technology were summarized; The composition program of underground blowout preventer system could implementing on the existing technical conditions were presented considering the function requirements and structure composition of underground blowout preventer system; The drill string shock-vibration communication mechanism in this program was analyzed and the process of drill string shock-vibration communication was simulated by finite element method based on the ground tests; a part of the equipments and processes were designed, and the indoor experimental studies of the key equipments were conducted.(1) The full research status investigation of the existing well control technology, well control equipment and down hole communication technology showed that existing well control technology and equipment has been unable to meet the safety requirements of sensitivity strata drilling and the new well control process and well control equipments has become the hot research focus of well control.(2) The underground blowout preventer system was divided into four functional modules, i.e. the packer module, overflow monitoring and early warning module, the down hole communication module and the packer module after killing and the work content and mechanism of each functional module were thoroughly studied based on the detailed analysis of the function requirements of the underground blowout preventer system. By comparing and summing the advantages and disadvantages of the various functional modules achieved by existing technology, combined with the functional requirements of underground blowout preventer system, the composition program of underground blowout preventer system could implementing on the existing technical conditions were presented. The program abandoned the traditional underground two-way communication thinking. This program forecast the bottom hole overflow information by bottom hole pressure monitoring and diagnosis, transmit the overflow warning information up by the shock and vibration of the bottom hole drill string explosion, pass the instruction to the down hole annulus BOP through the drill pipe, pack-off and re-open underground annulus BOP by putting down and lifting the drill string.(3) on the basis of the summary of previous studies, the drill string structure and vibration type was analyzed; the vibration propagation equations of drill string axial vibration, torsional vibration, and lateral vibration were established; the multiple wave effect and attenuation reason of drill string vibration was analyzed.(4) The damping factors of the drill string free vibration kinetic analysis were determined by using finite element analysis method, combined with the outdoor experiments of drill string free vibration, to take a=0 and β=0.0085 as Rayleigh damping parameters, the error was less than 7% as comparing the simulation results with the experimental test results. The acceleration output waveform and the sound pressure curve of different point position on drill string were obtained by applying these damping parameters to the impact vibration simulation of drill string under drilling condition. The sound pressure curve of different point position between the two shock vibrations in a certain interval of time was obtained. The results provide some reference to the application of information transmission of drill string shock vibration.(5) The down hole annulus BOP and down hole pressure monitoring and vibration signal excitation device were designed in detail, drawing processing maps and assembling and interference analyzing by three-dimensional modeling method. The function implementation process down hole annular BOP was simulated under the three-dimensional modeling state.(6) The indoor experimental study of underground annulus BOP was carried out by assembling the underground annulus BOP and testing the basic extrusion function of rubber can. The outdoor experiment of drill string shock vibration transmission was carried out providing some demonstration data for the drill string simulation. |
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