Study On The Technology Of The Oil Well Perforation In The Offshore Oil Well

With the decrease of reserves in land oil field,the development of offshore oil field has become the focus of oil exploitation in China.However,the development and exploitation of offshore oilfields are different from those of terrestrial oilfields,and are influenced by various factors such as technical level and marine environment.Especially,there has not been a complete method of depth calibration in the pre-perforation deep-tuning operation.The lack of accurate location of the target zone limits the development of offshore oilfields to a large extent.According to the actual situation of field operation in offshore oil field,this paper puts forward the technology of pipe string depth correction while drilling,locates the pre-positioned radioactive source when casing is lowered by gamma detector,and transmits the position information to the ground by means of acoustic wave with drill rod as the medium.Based on the investigation and analysis of offshore oil field,the scheme of pipe string depth calibration while drilling is designed,the transmission characteristics of sound wave in drill pipe are analyzed,the down-hole transducer model is established,and the possible errors of depth calibration system are analyzed.On the basis of the research and analysis,the down-hole system including down-hole high voltage power supply,transducer and gamma detector,and the ground system used for acoustic wave reception are designed and completed.An experimental platform has been set up in the laboratory,and simulated experiments have been carried out on the deep-tuning system of pipe-string while drilling,and repeated experiments have been carried out by constantly changing the position of radioactive sources.The experimental results show that the depth calibration technique of pipe string while drilling can effectively locate the target layer and transmit the position information to the ground with the error range within 20 cm.This method provides the basis for the deep-tuning operation of offshore oil field and lays the foundation for the practical application in the field.