OCTG Premature failures Due to Metallurgical Variance and Differential Electrochemical Behaviour of Exterior and Interior Walls
Saad M. El-Raghy,
Abdel-Alim H. El-Sayed,
Nabil A. Tayeb
Issue:
Volume 2, Issue 3, May 2014
Pages:
28-35
Received:
27 May 2014
Accepted:
9 June 2014
Published:
20 June 2014
Abstract: Previous studies on oil well’s unpredicted failures referred to uncertainty in interpreting the phenomenon of the prone of the external walls of Oil Country Tubular Good OCTG to the corrosion attacks more than the interior walls. In this study the tubular goods standards, failure analyses procedures and manufacturing tubular processes are reassessed. Theoretically manufacturing processes must show differential metallurgical heredities and residual stresses on OCTG exterior and interior walls. This fact regarded as an insignificant issue on most corrosion failure analyses, whereas any cut of the base metal from anywhere of a pipe, supposed to represents overall pipes in services condition. In this study, Full Ring Corrosion Cell Kit (FRCCK) setup has been built and full ring specimens prepared from L-80 grade tubing. Open circuit and galvanic corrosion tests have been run on exterior and interior walls separately in multi-concentration brines. Metallography shows slight difference of the microstructure and the ferrite/perlite phase’s ratio between inner and outer surfaces, but electrochemically the results indicate that there are significant differences of corrosion behaviors between exterior and interior surfaces. This approach may lead to reassessment of tubular goods corrosion manufacturing processes, inspections, failure interpreting, designing, specifications and quality standards, by cheap, fast, and reliable electrochemical non-destructive testing (NDT).
Abstract: Previous studies on oil well’s unpredicted failures referred to uncertainty in interpreting the phenomenon of the prone of the external walls of Oil Country Tubular Good OCTG to the corrosion attacks more than the interior walls. In this study the tubular goods standards, failure analyses procedures and manufacturing tubular processes are reassesse...
Show More
Investigation of Fluid Properties and their Effect on Seismic Response: A Case Study of Fenchuganj Gas Field, Surma Basin, Bangladesh
S. M. Ariful Islam,
Md Shofiqul Islam,
Mohammad Moinul Hossain
Issue:
Volume 2, Issue 3, May 2014
Pages:
36-54
Received:
23 June 2014
Accepted:
10 July 2014
Published:
20 July 2014
Abstract: The Fenchuganj Gas Field is one of the water-drive gas fields in the Surma Basin, Bangladesh. Due to gas production water saturation is increasing day by day. However, fluid properties of the reservoir at the present state in the gas depleted condition should be addressed with proper prediction. In this paper, we represent some modeling results which evidences that the pore fluids have a significant effect on the acoustic impedance and the Poisson’s ratio of the reservoir rock which is directly correlated with seismic amplitudes at constant pressure with Batzle-Wang model and Gassman-Boit models. Moreover, these models with varying pressure and water saturation conditions show the reasonable predicted fluid modulus against pressure. The reservoir modeling from irreducible water saturation conditions (90% gas saturation) to residual gas conditions (10% gas saturation) provides a pathway to calculate values at reservoir conditions from logging conditions. Fluid bulk density increases when water saturation increases with constant pressure and stay around constant when water saturation increases with pressure fall. But overall it increases through the production path that we assumed. Amplitude versus Offset (AVO) analysis also consistent with other studies models which show that seismic reflection of p-wave changes due to change of pressure and water saturation of the reservoir rock layers. The AVO response decreases with increases of water saturation of the gas zones. The evaluation of fluid properties enables seismic data to be used more powerfully. This study is also showing that both gas zones of the Fenchuganj are under gas sand category 3. We suggest that the modeling of fluid property in determining the usefulness of time lapse seismic, predicting AVO and amplitude response, and making production and reservoir engineering decisions and forecasting in the study field.
Abstract: The Fenchuganj Gas Field is one of the water-drive gas fields in the Surma Basin, Bangladesh. Due to gas production water saturation is increasing day by day. However, fluid properties of the reservoir at the present state in the gas depleted condition should be addressed with proper prediction. In this paper, we represent some modeling results whi...
Show More
