| With the increasing of oil and gas exploration,deep oil and gas resources has become the focus of major oil production and storage.The exploration and development strategic objectives of Tarim Oilfield are also turned to the deep oil and gas reservoirs which are geological complex and difficult to mining.However,due to the complicated geological conditions and strong anti-drilling characteristics in the deep stratigraphic oil and gas reservoir drilling,the problems such as low drilling rate and frequent drilling accidents are caused in the mining operation of Tarim Oilfield,which leads to a significant increase in drilling costs.In this paper,a new drilling technology based on torsional impact rock breaking is proposed,and the mechanism of torsional impact rock breaking is studied by methods of theoretical research,numerical simulation and field experiment.The main research contents and research results are as follows:1.Based on the geological characteristics of the Tazhong formation in Tarim Oilfield,the present drilling status is analyzed,and the drilling difficulties are further summarized.The torque shock drilling speed-raising technology which can greatly improve the drilling rigging speed in the Tazhong formation and reduce the cost of drilling was put forward by comparing the advantages and disadvantages of the drilling speed application technology has been applied and field applications conditions.2.The relationship between the anti-drilling parameters of the rock in the Tazhong formation and the depth distribution is analyzed statistically and the logging interpretation model of rock mechanics parameters is established.Application of R/S analysis shows that the stratigraphic logging data in the Tazhong formation have good fractal characteristics and correlation.In addition,The self-similarity of the macroscopic change trend and the fine change of the internal spatial structure is confirmed based on the stochastic midpoint displacement method.3.The physical model and mathematical model of the single-blade rock breaking rock and the multi-blade rock breaking are established.The governing equations of the bit movement under the torsional impact are deduced,and the trajectories of the drills under the torsional impact are analyzed.It is confirmed that the torsional impact rock breaking can reduce the slippage of the drill bit and improve the crushing efficiency of the rock.4.Based on the theory of vibration,the physical model and mathematical model of the torsional impact drilling system are established to solve the dynamic model of the two working states which includes stabilized drilling and unsteady drilling of torsional shock drilling.The influence factors of the torsion impact drilling process dynamic characteristics is analyzed from five factors such as drilling parameters,drill string characteristic parameters,Bit characteristics parameters,rock characteristic parameters and the characteristic parameters of the interaction between the bit and the rock.5.The theoretical basis,working principle and technical characteristics of the design of the torque impact tool was introduced.The field application effect of the J13 well of a block in the Tazhong area through the torque impact tool proves that the torque impact tool can improve the PDC bit drilling speed,reduce drilling time and drilling costs.Torsional impact rock breaking is an important direction for development of drilling technology in the future.The research on rock breaking mechanism of torsional impact can provide strong theoretical guidance for oil extraction of Tarim Oilfield.At the same time,the self-developed torsional impactor also provides technical support for oil exploitation in major oil fields. |
PDF Full Text Request