Deep Hard Formation Drilling Stick-slip Vibration Characteristics And Vibration Reduction Method

The stick slip vibration of the bit is a technical difficulty in the drilling of the deep and tough formation. With the developments of oil and gas exploration in our nation, it turns into deep formation or deep sea, and stick slip vibration of the bit has become a bottleneck that restricts the process of efficient drilling. It is difficult to research the stick slip vibration of the bit because it relates to factors such as faraway from the surface or high temperature and high pressure, which results into slow progress of the research. In this paper, the research statuses are going to be investigated and influences of the vibration will be obtained. Characteristics of the stick slip vibration and movement pattern of the bit are going to be researched, suppression methods of the vibration and high frequency torsional impact drilling will be analyzed. Research contents in this paper are shown as follow:(1) Combining the research status and field cases of the stick slip vibration to obtain the influences of the stick slip vibration.(2) Nonlinear contact between rock and the bit and the damage value of the rock will be analyzed to obtain the interaction mechanisms of the rock and bit; obtaining the formation mechanism of the stick slip vibration by researching the rock breaking process and function mechanism by simulating the rock breaking and effect raw.(3) Simplify the drilling system into a single freedom model, analyze the single freedom without damping free vibration, single freedom free vibration with damping and single freedom forced vibration with damping; simplify the drilling system into a two freedom model and infinite freedom model to obtain the kinetic characteristics of the stick slip vibration.(4) Analyze the suppression methods of the stick slip vibration, including changing the drilling parameters by using MWD, shock and vibration mitigation process, active damping controlling system, PI controlling system, decoupling stick slip from the whirling, combining the RSS with MWD, optimizing the drilling parameters.(5) Design the torsional impact drilling assembly and conduct the feasibility measures both on simulation and test to obtain the characteristics of the rock breaking and bit vibration of high frequency torsional impact drilling.In the paper, interaction between bit and rock, mechanisms of the stick slip and dynamic characteristic of the bit, mechanism in enhancing the ROP of high frequency torsional impact will be researched, the research achievements provide theoretical basis and scientific guidance for the future work.