Research On Surface Cracks And Reliability Of Residual Life In Sucker Rods

There are about 80% using sucker rod pumping technology in the oil- field production of our country. There are about 75% producing oil to use the sucker rod .Yet, there are about last ten million of meters increasing sucker rods every year. So, it is important for the sucker rod to produce oil in the country.The sucker rod is the main bearing structure member in the sucker rod system. There happened frequently to be fracture and disconnected accidents during its working time. It influences oil production seriously and it causes great economic loss. How to prevent or reduce the accidents in the oil wells, and how to promote its reliability when it is working, it is worth researching.In this paper, the main study follows: (1) According to the investigation and researching on the oil-produced wells history, collect the failure phenomenon, arrange analysis data, set up failure tree of the sucker rod system, do qualitative and quantitative analysis, and find out the weak link when it works . (2) To the weak link, study its material and its member by experiments. Find out probability distribution regularity of every parameters (fracture toughness, mechanical strength, crack defect fatigue growth rates and thresholds.). (3) Study stress-intensity factor of the sucker rod surface crack fatigue. (4) Calculate the sucker rod remaining life and its reliability based on rupture-mechanics and reliability theories. (5) Ensure the threshold and reliability of the sucker rod crack size.In this paper, the main research fruit and its application range are: (DSet up failure tree of the sucker rod system and calculate several importance quantitative index . It indicates the direction to improve its reliability for its design, production and application. (2) It provides the quantitative basis for reliability analysis of the...