Abdennour Seibi

Dynamic effects of mandrel/tubular interaction on downhole solid tubular expansion in well engineering

The expansion process subjects a solid tubular to large plastic deformations leading to variations in tubular thickness and length, which may result in premature and unexpected failures. It was noticed that the expansion process induces wall thickness imperfections due to excessive local plastic deformation as a result of mandrel sticking and slipping relative to the expanded tubular; such irregularities increase the probability of failure. Mandrel sticking may be the result of lack of enough lubrication, tubular surface irregularities, and the presence of welded and/or threaded connections, which require higher drawing force to push the mandrel forward. When the drawing force required to overcoming the maximum static friction and the mandrel forward motion is assured, the mandrel slips relative to the expanded tubular. This “stick-slip” phenomenon results in mandrel oscillations that affect the tubular response in terms of further reduction in thickness and may jeopardize the tubular capacity under normal operating field conditions. Therefore, the present work studies the mandrel dynamics and their effect on the tubular structural response. A mathematical model, which is an extension of the quasistatic tubular expansion analysis, has been developed to describe the dynamic friction effects of the stick-slip phenomenon. A special case of tubular expansion consisting of 25% expansion ratio of a 4/12 in. liner hanger was considered. It was found that the level of mandrel oscillations is in the order of 1–2 mm around its equilibrium position resulting in tubular thickness reduction of approximately 9% on top of its variation caused by the steady state expansion process. This increase in thickness reduction may affect the postexpansion collapse strength of the tubular. DOI: 10.1115/1.3066412

Post-Expansion Tube Response under Mechanical and Hydraulic Expansion - A comparative Study

This paper presents a mathematical model of post-expansion tube response under mechanical expansion. The stress, pressure, and displacement waves propagating through the tube-fluid system and their effect on the tube response are studied. The model takes into account coupling between the solid tube and surrounding fluid at the borehole/ expanded tube annulus, as well as the damping effect on tube structural response. The paper also conducts a comparative study aiming at studying the post-expansion tubular fluid response and identifying the different features between hydraulic and mechanical solid tube expansion. The results showed that the mechanical expansion is less harmful to the tube structural integrity. Unlike the hydraulic expansion, which resulted in local stress buildup along the tube, the mechanical expansion was characterized by low equivalent stress throughout its length and a smooth dying out response.

Shape Factors for Irregular Glass Reinforced Plastic Pipes – An Analytical and Numerical Approach

This paper presents the development of a mathematical model based on curved beam theory of composite pipes with irregular shapes under diametral loading. The analytical solution was validated through finite element models of the same pipe shapes under similar loading conditions. Four shapes (circular, elliptical, rectangular, and egg shaped pipes) were considered in this study. The analytical and finite element results were used to estimate the shape factor defined by the ratio of the maximum tangential stress of an irregular shape over the maximum tangential stress for a circular pipe. Comparison of the load-deflection curves for the four different shapes revealed that the egg pipe is the stiffest among the rest of the pipes while the square shape is the most flexible one. The analytical solution and finite element results were used to determine the shape factor for the four pipe shapes taking into account the circular pipe as the base shape. Both results were in good agreement and can be used as design guidelines for the irregular shapes without resorting to the conduct of any further testing.

Combined Effect of Temperature and Soil Load on Buried HDPE Pipe

HDPE pipes，mostly buried underground, have been widely used in industry. Much research has been done on pipe property changing with time or temperature. But thermal expansion of pipe was neglected. This paper investigated the combined effect of soil load and temperature on HDPE pipe with introduction of thermal expansion. Stress and deflection variation with time of buried HDPE pipe were studied in ABAQUS. Result showed pipe temperature had great influence on buried HDPE pipe performance. Thermal stress was much larger than stress caused by soil load. And thermal expansion prevented pipe from deflecting due to soil load, which can protect HDPE pipe in applications.

Analytical Method for Temperature Distribution in Buried HDPE Pipe

HDPE pipes have been widely used in industry, which were mostly buried underground. Because of special material properties, which were affected by temperature, it is necessary to get the temperature profile of buried HDPE pipe. Most past solutions for temperature distribution in buried pipe were numerical ones. The aim of this paper was to present a simple analytical model under steady-state heat transfer condition with a new special heat transfer coefficient introduced. FEM method was used to check this model. The influences of fluid temperature, soil surface temperature and soil depth on pipeline temperature were also analyzed. The results showed a good agreement between the analytical model and FEM method. And fluid temperature in pipe was proved to be the key factor that affected the pipe temperature .

Vibration Analysis of Thick Arbitrarily Laminated Plates of Various Shapes and Edge Conditions

Free vibration analysis of arbitrarily laminated plates of quad, penta and hexagonal shapes, which have combinations of clamped, simply supported and free edge conditions is performed. The finite element formulation is based on first and higher order shear deformation theories to study the free vibration response of thick laminated composite plates. A finite element code is developed incorporating shear deformation theories using an 8-noded serendipity element. The effect of plate shape, arbitrary lamination and different edge conditions on natural frequencies and mode shapes are investigated. A systematic study is carried out to determine the influence of material orthotropy and aspect ratio on free vibration response. For various cases, the comparisons of results from present study showed good agreement with those published in the literature.

Damping effect on mechanical waves in an elastic solid expanded tubular

The present paper studies the dynamics of submerged expanded elastic tubes due to postexpansion sudden mandrel release known as pop-out phenomenon. A mathematical model describing the dynamics of the borehole-fluid-tube system is presented. Coupling of the fluid-structure interaction and damping effects were taken into consideration. An analytical solution for the displacement, stress, and pressure wave propagation in the fluid-tube system was obtained. The developed model predicted localized critical regions where the structure might experience failure.

Dynamics of Submerged Expandable Tubes in Borehole Wells

Solid Expandable Tubular Technology (SETT) is a new development in the petroleum industry. It consists in accomplishing hydraulic expansion of a submerged tube by propelling a mandrel through it using a differential pressure. The progress of the mandrel deforms the tube beyond its elastic limit. Towards the end of the expansion process, the mandrel pops out of the tube resulting in displacement, stress and pressure waves. A mathematical model is developed to describe the dynamics of the tube-fluid system due to the pop-out phenomenon. The model takes into consideration the effects of the coupling between fluids and structure as well as the inherent system damping on the response. Through a specific field case, the model provides an analytical solution describing the wave propagating in the tube-fluid system and identifies the potential failure locations.Copyright