Remarks on Modeling the Oil Film Generation of Rod Seals

The oil film generation of a U-cup rod seal and the oil film thickness on the rod after outstroke were analyzed analytically, numerically, and experimentally. The analyzed sealing system consists of an unmodified, commercially available U-cup, a polished rod, and mineral oil. The inverse theory of hydrodynamic lubrication (IHL) and an elastohydrodynamic lubrication (EHL) model—both based on the Reynolds equation for thin lubricating films—were utilized to simulate the oil film generation. In the EHL analysis, physical parameters and numerical EHL parameters were varied. Both the analytical and numerical results for the varied parameters show that the film thickness follows a square-root function (i.e., with a function exponent of 0.5) with respect to the product of dynamic viscosity and rod speed, also referred to as the duty parameter. In comparison to the analytical and numerical results, the film thickness obtained via ellipsometry measurements is a function of the duty parameter with an exponent of approximately 0.85. Possible causes for the discrepancy between theory and experiments are discussed. A potential remedy for the modeling gap is proposed.

Aplicação dos métodos de cálculo aproximado e de Gibbs na determinação das cargas atuantes no bombeio mecânico com hastes

O bombeio mecânico é o método de elevação artificial mais utilizado no mundo e a determinação de seus parâmetros operacionais é de extrema importância para a otimização de seu desempenho. O controle das cargas máximas e mínimas na haste pode garantir um tempo de vida útil maior para as hastes e para todo o sistema de bombeio mecânico (Pons, 2014). A simulação do comportamento da coluna de hastes é o método mais adequado para a descrição deste sistema. Neste trabalho são utilizados o método do cálculo aproximado, e o método de Gibbs para o cálculo dos parâmetros operacionais PPRL – Peak Polished Rod Load, MPRL – Minimum Polished Rod Load e PT – Peak Torque. O método de Gibbs foi aplicado através do software SROD® e os dados reais para o estudo foram obtidos do banco de dados da Petrobras retirados do software TWM® (Total Well Management). É realizada a comparação dos resultados da simulação com duas pressões de sucção diferentes fornecidas pelo software TWM, a pressão de sucção da bomba calculada a partir do teste acústico e a pressão de sucção da bomba calculada a partir da carta dinamométrica. Os resultados mostram que para o método do cálculo aproximado a pressão de sucção da bomba calculada a partir do teste acústico é a mais adequada a ser utilizada, e para a modelagem dinâmica via SROD® a pressão de sucção mais adequada é aquela proveniente da análise da carta dinamométrica.

Judgment method of working condition of pumping unit based on the law of polished rod load data

At present, oil companies are committed to applying the theory and means of mathematics or data science to the research of oilfield data rules. However, for some old oil wells, aging equipment, complex environment and backward management, cause the authenticity and accuracy of the data collected by the equipment cannot be determined. According to the actual engineering demand of the old wells, this paper proposes a method based on principal component analysis, cluster analysis and regression analysis to mine and analyze the data of polished rod load of old oil wells, so as to judge the working conditions of the oil wells. Combined with the application of this study in several operation areas of some oilfields, the findings of this study can help for better understanding of the working condition information hidden in "big data" of oilfield. Meanwhile, the PCA method can reduce the complexity of the original data, the regression equation can calculate the size of the polished rod load more accurately, and the prediction model can effectively judge the working conditions of the old oil wells on site.

Calculating the Load on the Rod Suspension in Unsteady Oscillation Motion of the Well Pumping Unit Rods

The efficiency of a rod pumping unit is determined by the straightness of its rod string, which is impacted by the load when the rod string is in motion. Determining the dependence of the load impacting the rod suspension on the dynamic forces is one of the major issues in ensuring its straightness. In order to provide equal distribution of the stresses along the entire length of the polished rod under dynamic loading, it is necessary to determine the load on its surface, which is impossible without the equation of unsteady motion of the rod string. To this end, the article examines the issues related to the equation of unstable motion of well pumping unit rods. Formulae for calculating the loads acting on the rod suspension point are derived, and the equation of the rod string motion and load on the polished rod after the initial deformation is obtained.

A Novel Method for Diagnosis of Sucker-Rod Pumping Systems Based on the Polished-Rod Load Vibration in Vertical Wells

Summary The pump dynamometer card is a direct reflection of the operating conditions of the downhole pump, which is important for the diagnosis of sucker-rod pumping systems. In this paper, we propose a novel diagnostic method based on the estimation of the parameters from the polished-rod load vibration signal of sucker-rod pumping systems in a vertical well. In this study, we deduce a new analytic solution of the 1D wave equation of the sucker-rod string, which can be used for the predictive and diagnostic analyses. The relationship between the polished-rod load vibration and the pump equivalent impulse load based on the analytic solution is studied, and the diagnostic parameter estimating method is proposed. Therefore, the pump dynamometer card calculated method based on the surface dynamometer card is realized. This study shows that the method is efficient.

Analysis of the Dynamic Response of the Mechanism of Conventional Sucker rod Pumping Units

In the kinetostatic study of the mechanism of the sucker rod pumping units, the cinematic motion parameters of the elements are considered to be known, assuming that the cranks have a constant angular velocity imposed by the operating functioning conditions of the pumping unit. The paper analyzes the dynamic response of the mechanism of these pumping units, which implies the determination of the variation of the angular acceleration of the cranks during the operating cinematic cycle. A series of results regarding the determination of the variation of the angular acceleration of the cranks during the cinematic cycle in the case of the mechanism of a C-640D-305-120 pumping unit are presented. The obtained results are checked by comparing the experimental curves of variations of the acceleration at the polished rod with those obtained by simulation using a computer program developed by the authors in which the angular acceleration of the cranks was taken into consideration.

Multilevel Simulation of Physical and Engineering Problems

This article discusses peculiar features of simulation of physical and engineering problems, criteria for their efficient simulation in development environment are formulated. Software for simulation of complex dynamic objects is briefly analyzed (as superclass of physical and engineering problems). Provisions of the developed approach to multilevel computer simulation of physical and engineering problems in the frames of multilevel component circuits formalism are described. Peculiar features and capabilities of this approach are exemplified by simulation of forces on polished rod of sucker-rod pump for extraction of petroleum

A DAMAGE ANALYSIS OF SUCKER ROD STRING DUE TO EXCEEDS STRESS ON ARTIFICIAL LIFT SUCKER ROD PUMP WELL IR-01 TALANG AKAR PENDOPO FIELD

ABSTRAK Sumur IR-01 menggunakan sucker rod pump sebagai metode pengangkatan buatan dalam memproduksikan minyak. Data riwayat sumur pada tahun 2017 menunjukkan bahwa sering sekali mengalami permasalahan sucker rod putus, sehingga perlu dilakukan upaya pemecahan masalah. Analisis yang digunakan untuk mengetahui penyebab kerusakan rangkaian sucker rod pada sumur IR-01 adalah dengan melakukan perhitungan beban pada polished rod dan kinerja SRP secara teori, serta menggunakan interpretasi data hasil dynamometer test guna mendapatkan data aktual beban polished rod khususnya tingkat stress sucker rod di lapangan. Setelah dianalisis penyebab permasalahan maka dapat dilakukan upaya penanganan masalah dengan memberikan rekomendasi perencanaan ulang untuk mengatasi permasalahan sucker rod pada sumur IR-01.