Evaluation of the Customer Satisfaction Index for Wellhead Blowout Preventers of China’s Petroleum Industry——A new method based on PLS

This paper establishes an evaluation model of the customer satisfaction index for the wellhead blowout preventers of China＇s petroleum industry based on evaluation models of the customer satisfaction index at home and aboard, and by considering the consuming situation in China and the features of the China＇s petroleum industry. For the existence of： （1） multiple correlations among the factors in the model; （2） the variables need to be explained, but that are hard to observe; （3） the customer satisfaction degree of observation variables appears the shape of skewness or two or three peaks, the correlations between the satisfaction index and its factors cannot be described by common multiple regression. This paper uses a partial least squares （PLS） method based on principal components and typical correlative analysis to solve the problem. When PLS is used in the model of the customer satisfaction index of the wellhead blowout preventers, the latent variables and the explanation degree coefficient of the manifest variable to the corresponding latent variables are estimated by PLS path analysis, and the influencing coefficient among the latent variables in the model is estimated by PLS regression analysis. PLS is also be used to calculate and analyze the model and disclose the correlations among the structural variables as well as the correlation between structural variables and its corresponding observation variables, evaluating results of which provide useful information for petroleum industry to improve the product quality and to the enhancement of the customer satisfaction to the product.

BOP shear force evaluation under complex scenarios

As the“throat”of the drilling well control system,ram blowout preventers(BOPs)can effectively prevent blowout accidents.However,the ram shear mechanism under complex working conditions is unclear,and it is difficult to evaluate the ram BOP shear force,leading to frequent shear failure accidents in oilfields.Aiming at the above problems,this paper takes the double-V ram BOP as the research object,and integrates the methods of theoretical analysis,simulation modeling,and test verification to analyze the shear force in the pipe shear process under both static and moving conditions.A ram BOP shear force evaluation method is proposed based on equivalent stress.Finally,by comparing with calculation data and experimental data,the error between them is less than 5%,demonstrating the applicability and effectiveness of the proposed method.The research results can provide a theoretical basis for oilfield operations of ram BOPs.

Sealing performance analysis of rubber core of annular BOP:FEM simulation and optimization to prevent the SBZ

The present work studies the influence of oil pipe joint passing through annular blowout preventer(BOP)on its sealing performance in high pressure gas wells under snubbing service.When the oil pipe joint passes through the BOP,due to the change of its structure,it is easy to cause the rubber core seal failure of the BOP,resulting in the leakage of toxic and harmful gas in the well,which seriously threatens the safety of the operators.Aiming at the problem of gas leakage caused by rubber core seal failure of annular BOP,based on the rubber large deformation theory and rubber core seal mechanism,a dynamic finite element model of rubber core-oil pipe joint is established,and the correctness of the model is verified by comparing the failure of rubber core on site;The results show that when the oil pipe joint passes through the BOP,a sealing buffer zone(SBZ)will be formed at the upper and lower shoulder of the joint,and the contact stress of the rubber core will decrease by 10 MPae30 MPa;Because of the funnel effect of the rubber core,the damage of the rubber core caused by the running oil pipe joint of the BOP is greater than that caused by the lift oil pipe joint;When lifting oil pipe,the existence of SBZ is easy to cause gas leakage in the well;The optimized structure of oil pipe joint with small inclination and long shoulder can significantly reduce the influence of SBZ on the sealing performance of BOP.The research work in this paper is of great significance to improve the dynamic sealing performance of BOP.