Karthik Annadorai

SPE 147205 - Materials Selection: A Systems Engineering Approach

2011 Abstract, Eric Caldwell, Karthik Annadorai, Grant Gibson, Lee Jordan

Subsea and topsides materials selection is becoming a vital part in the development and long term sustainability of deepwater oil and gas production facilities. Increasing challenges associated with capital and operating cost constraints, schedule compression, remote locations, and the need to deploy materials ever closer to their known limits makes fit for purpose materials selection a complex and difficult issue that crosses many different discipline boundaries. Materials selection is primarily governed by corrosion engineering principles and applied chemical inhibition practices, and then by project specifics. However, there are two different practices that are generally followed that dictate how materials are ultimately selected. The first is by a standard materials selection process using guidance such as that provided in NORSOK M-001, and the second is by using a more informal system with limited guidance that involves individually selecting materials for a specific project.

 In actuality, the materials selection process is a combination of both. The selection process to identify which materials are considered appropriate is routine and straightforward and is dictated by various corrosion parameters and associated risks. Often this high-level assessment does not appropriately address project specifics, so causing the final material selections to be substantially different from those initially proposed.

One of the specific items that often drives this change in materials selection philosophy is the use of chemical inhibitors for corrosion inhibition and the perceived feasibility and level of risk associated with this. Use of a systems engineering approach to material selection can be used beneficially as a process that accelerates the determination and initial optimization of the materials, and the selection of chemicals and their injection locations, and associated monitoring methods and locations in a given topsides, subsea or water injection system design.

Source: SPE Annual Technical Conference and Exhibition, 30 October-2 November 2011, Denver, Colorado, USA

Copyright 2011. Society of Petroleum Engineers

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SPE 147552 - Integrated Field Optimization Strategy Applied to an Offshore Water Injection Project

2011 Abstract, F.R. Chaban, SPE, L.C. Jordan, SPE, and K.M. Annadorai, SPE, Gibson Applied Technology and Engineering; T.W. Wilkinson, SPE, and P. Myers, Energy XXI

 Some of the most significant challenges faced with respect to the management of offshore water injection projects are associated with maintaining injectivity into the reservoir and with handling H2S produced due to reservoir souring. This paper presents the process followed and findings generated by a comprehensive review of a mature water injection project performed with the goal of delivering a coordinated operating strategy that would maximize the life of field revenues associated with water injection.

An integrated and comprehensive field optimization approach to maximize the whole-life value of the total asset was undertaken. Aspects covered included water injection system operating practices, mechanical design and integrity management of the injection system, the chemical treatment program followed for both the injection and production streams, and reservoir modeling and production management.

Recommendations resulting from this review were prioritized based on their impact on the whole-life performance of the asset, rather than the more common practice of separating the injection and production system reviews or the assessments of reservoir management and facility operation. Areas of particular benefit were identified in association with implementation of an active souring control strategy to reduce future risks to the production system metallurgy by sulfide stress cracking (SSC), a focus on integrity management of the water injection system to maximize long-term system availability, and the implementation of an inter-well water tracer injection program to enable the validation of current reservoir models and support the placement of future injectors and producers.

Source: SPE Annual Technical Conference and Exhibition, 30 October-2 November 2011, Denver, Colorado, USA

Copyright 2011. Society of Petroleum Engineers

SPE 125785 - Effect of THPS on Discharge Water Quality: A Lessons Learned Study

2010 Abstract, Karthik Annadorai, SPE; Adam Darwin, GATE, LLC

Biocides typically have an adverse impact on overboard water. THPS (tetrakishydroxymethyl phosphonium sulfate), one of the most commonly used biocides offshore has a similar effect on produced water. The effect of THPS on seawater used for hydrotesting and bulk storage is seldom studied and rarely documented. The effect of temperature, pH, water depth, dissolved oxygen concentration and various ions in the system is important to note. Once a certain volume of water is treated with any chemical, it is now deemed to be chemically treated seawater which cannot be discharged unless verified using the NOEC (No Observable Effect Concentration) testing method.

This experience will provide a detailed understanding of the discharge of chemically treated seawater as well as the interaction of THPS with potential ions in the matrix. Additionally, regular sampling and associated analyses will be presented that demonstrate the degradation and half-life of the THPS molecule in varying temperatures.

Periodic sampling of the THPS chemical in the seawater has provided a detailed understanding of the half-life degradation of the chemical. The interaction of the chemical with the cations present in the system and subsequent aversion to the neutralization reaction with hydrogen peroxide has also been studied and presented.

Source: SPE International Conference on Health, Safety and Environment in Oil and Gas Exploration and Production, 12-14 April 2010, Rio de Janeiro, Brazil

Copyright 2010. Society of Petroleum Engineers

NACE 10401 - Prevention Of Corrosion In Carbon Steel Pipelines Containing Hydrotest Water - An Overview

2010 Abstract, Adam Darwin, Karthik Annadorai, Gibson Applied Technology and Engineering, LLC; Krista Heidersbach, Chevron Energy Technology Center

A critical step in proving a pipeline is fit for operational use is the hydrostatic test, in which it is filled with water and pressurized to 125% of its Maximum Allowable Operating Pressure (MAOP). The water that is used in this testing can cause corrosion of the pipe, potentially leading to failure early in its operating life. Failures have occasionally been reported even before a pipeline enters service.

The most common mechanisms by which carbon steel pipelines may undergo corrosion on exposure to hydrotest water are Microbially Induced Corrosion (MIC), oxygen-related corrosion, galvanic corrosion and under-deposit corrosion. An overview of these mechanisms is presented, along with a discussion of the influence of different environmental factors on them. Factors considered include water source, degree of filtration, exposure period and temperature, air pockets, presence of internal pipe coatings and future pipeline service conditions.

Maintaining the risk of pipe corrosion from hydrotest water within acceptable limits is discussed. Factors considered are:

How long the untreated water may be allowed to be present in the pipeline.

Should water treatment be required, what must be used?

Disposal requirements for the treated water, including chemical treatments.

Source: CORROSION 2010, March 14 - 18, 2010 , San Antonio, TX

Copyright 2010. NACE International

SPE 110205 - Successful Application of Chemical Injection Rate Control Valves

2007 Abstract, H.J. Duhon, SPE, and K.M. Annadorai, SPE, Gibson Applied Technology and Engineering

This paper presents an overview of a systems approach to the design and troubleshooting of IRCVs (Injection Rate Control Valves) used in deepwater chemical injection systems.  The inherent problems associated with these simple flow regulators stem largely from the failure of design engineers to take a systems view in design.  Along with the application of lessons learned from previous IRCV system failures, this systems approach provides a design method which will allow users to avoid many of the pitfalls inherent in design, installation, testing, commissioning and operation of IRCV systems.

Source: SPE Annual Technical Conference and Exhibition, 11-14 November 2007, Anaheim, California, U.S.A.

Copyright 2007. Society of Petroleum Engineers