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ABSTRACT V.S. Sastri discusses the ?Comparison of Techniques for Monitoring Corrosion Inhibitors in Oil and Gas Pipelines,? by S. Papavinasam, R.W. Revie, M. Attard, A. Demoz, and K. Michaelian, which was published in CORROSION 59, 12 (2003), p. 1,096-1,111. A reply from S. Papavinasam, R.W. Revie, M. Attard, A. Demoz, and K. Michaelian follows. KEY WORDS: electrochemical impedance spectroscopy, electrochemical noise, general corrosion rate, inhibitors, linear polarization, pipelines, pitting corrosion rate DISCUSSION Recently, a publication appeared with the title ?Comparison of Techniques for Monitoring Corrosion Inhibitors in Oil and Gas Pipelines,?1 in which the authors used weight loss, linear polarization resistance (LPR), electrochemical impedance spectroscopy (EIS), electrochemical noise (EN), and hydrogen probes to monitor corrosion inhibitors in oil and gas pipelines. The conclusions reached by the authors are such that the weight loss data gave 90% MRT (most repeated trend), LPR gave ~70% MRT, EIS gave 33% MRT, and EN gave 90% MRT. The authors also state that reliable EIS data could not be obtained on localized corrosion. The authors also point out that collection of EIS data requires a long measurement time, the need to get data at 20 frequencies, and the failure to model the system in terms of an equivalent circuit. The following are the comments on the use of EIS and EN in monitoring corrosion. EIS has been successfully applied to monitor corrosion systems for more than three decades, since the technique is capable of giving information on the corrosion mechanisms involving small amplitude signals without disturbing the properties of the system and the applicability to low-conductivity environments.2-4 The two fundamental difficulties in the application of EIS to the field monitoring of corrosion are the time involved in obtaining a full-impedance diagram and the interpretation of the EIS data. The difficulties were overcome by a method consisting of finding the geometric center of an arc formed by three successive data points on a complex impedance diagram.5-6 This analysis was further developed by permuting the data points involved in the projection of centers to obtain a population of projected centers, which could be used in evaluating the parameters behind an RC behavior.7-8 Field monitoring of corrosion using EIS and electrochemical noise was done at two sites, consisting of the evaluation of inhibitors in oil pipelines and the evaluation of biocides in reducing microbiologically induced corrosion. The results of the . eld tests have been documented in the literature.9-10 The results obtained from the field tests showed that the two inhibitors tested in the oil. eld operations were equally effective. Some data are given in Table 1.
Abstract. Technology has affected almost all aspects of now-a-days way to life of human beings and the economic activities globalwise. Technologically developed nations have been able to control effectively the trend of global economic growth and industrial development. Certainly, technology offers diversified opportunities for both developing and developed nations to achieve advanced levels of development. Therefore, technology transfer is becoming a strategic goal of developing nations. Several models of technology transfer are available for adaptation. However, successful technology transfer depends, to a large extent, on the individual sectors of technology application, and upon the effort of the recipient in acquiring the adequate infrastructure needed for adapting transferred technology. The petroleum sector in Saudi Arabia is the focus point of its economic activities and industrial development. Oil production in Saudi Arabia, beside being the main source of wealth, it is also the source of raw materials and energy requirement of various up-to-date petrochemical industries. In developing its petroleum and petrochemical industries Saudi Arabia has applied several models of technology transfer. In this paper we present the experience of Saudi Arabia in technology transfer in the upstream and downstream sectors of its petroleum industry, and describe the extent of its success in adapting advanced technologies. 502 BLOCK IX-TRANS PO RTATION Topic 6-Forum with Poster Sessions Shipping and Pipelining Chairman: M. DURNIN, Senior Vice President TransCanada Pipelines, Canada Vice Chairmen: A. WEGENER, Director, International Division, Norwegian Shipowners Association, Norway and D. ATTARD, International Marine Law, Inst., Malta Paper 1: The Shifting Trading Patterns for Tankers and the Aging Fleet, a Challenge for Tanker Owners and Charterers J. E. Sundnes, First Olsen Tankers Ltd., Norway Paper 2: Marine Oil Spill Response in Australia: A Model of Government and Industry Cooperation D. J. Blackmore, Australian Marine Oil Spill Center, Australia 513 Paper 3: Computer Aided Minimization of Crude Oil and Product Pipeline Transport Costs Paper 4: Transneft Economic Strategy on the Eve of 21st Century V. D. Chernyaev, E. M. Yasin and N. M. Cherkasov, Rosneft, Russia 525 505 A. Linke, Pichler Engineering GmbH, Germany 519 Paper 5: Stress Corrosion Cracking on Canadian Oil and Gas Pipelines J. McCarthy, National Energy Board, Calgary, Poster 1: Researches on Rhelogical Characteristics of Chinese Waxy Crude Oils Lu0 Tanghu and Zhang Yucang, CNPC, China Poster 2: Pipeline Transportation of Waxy Crudes in China Jiqing Chen, CNPC, China, Dafan Yan and Jingjun Zhan, University of Petroleum, China Poster 3: Kuwait Experience in Dealing with Oil Lakes/Oil Well Fires Mohammed A. R. Taleb, Kuwait Oil Co., Kuwait Alberta, Canada 537 541 548 550 503 B
van der Zwaag, C.H. (ResLab Reservoir Laboratories AS) | Stallmach, F. (SINTEF Unimed) | Basan, P.B. (Applied Reservoir Technology) | Hanssen, J.E. (Anchor/MI Drilling Fluids AS) | Soergaard, E. (Norsk Hydro A.S.) | Toennessen, R. (Saga Petroleum ASA)
C.H. van der Zwaag, ResLab Reservoir Laboratories AS, F. Stallmach, SINTEF Unimed*, P.B. Basan, Applied Reservoir Technology, J.E. Hanssen, Anchor/MI Drilling Fluids AS, E. Soergaard, Norsk Hydro A.S., R. Toennessen, Saga Petroleum ASA Abstract The objective of the study was to test a new methodology that combines non-destructive, high-precision analytical techniques to detect and quantify formation damage introduced by drilling fluids. Reservoir core material and standard Berea sandstone samples were exposed to synthetic oil based and water based drilling fluids under downhole conditions simulated by radial drainage, dynamic filtration experiments. Alterations in the rock pore structure were investigated using non-destructive methods including 10-MHz Nuclear Magnetic Resonance (NMR) relaxation measurements, NMR Imaging and Computed Tomography (CT) Scanning. Backscattered Electron Imaging (BSEI), core analysis and mercury porosimetry provided additional, quantitative information on baseline rock properties. Results show that several types of damage can be identified and quantified. Mud solids (barite) caused shallow, partially irremovable internal filtercakes. Polymers accumulated deeply inside core plugs and are considered to be potentially damaging. The synthetic oil based fluid introduced surfactants into the rock which could not be removed by backflooding. The study demonstrates the high potential of the methodology to generate comprehensive data on the type and distribution of components that can cause formation damage in reservoir rocks. Introduction Formation damage is the impairment to the productivity of hydrocarbon bearing rock formations caused by the combination of mechanical and chemical activities required to drill or complete wells or stimulate reservoirs. Wellbore damage occurs where introduced or released particles, water, emulsions or scaling products alter the hydrocarbon delivery system. Recognition and treatment of formation damage typically rely on core displacement tests in combination with traditional core analysis and petrographic analysis methods. Coreflood experiments are useful indicators of the changes in the baseline permeability, yet, they provide no direct insight into the causative and triggering mechanisms controlling damage. At present, any evaluation of the causative mechanisms combines coreflood experiments with petrographic procedures like secondary electron microscopy, cryogenic electron microscopy, thin section observation, X-Ray diffraction or X-Ray Fluorescence". Such approaches have either observational value, i.e. they are non-quantitative, or they may require to break the rock material prior to the analysis. CT-Scanning, on the other hand, is a well established quantitative and non-destructive analytical method in formation damage analysis. Furthermore, NMR relaxation measurements (cf. Attard et al.), as well as NMR-Imaging have been applied to investigate a large range of petrophysical phenomena, transport processes and chemical reactions inside rocks. Earlier applications of MR-Imaging in non-destructive formation damage analysis have, for example, been reported by Fordham et al. Basan and Pratt combined Backscattered Electron (BSE) Microscopy with image analysis to both identify drill mud components in pore structures and quantify their abundance. Using any of these methods alone, will produce information limited to the individual character of the method. In combination, however, these non-destructive methods will provide comprehensive, quantitative data on the type and distribution of formation damage in a rock. P. 173^
Attard, M., Amoco (UK) Exploration Co. SPE Member Abstract This paper discusses the occurrence of annulus pressures in the North West Hutton oilfield, offshore UK, and how the problems associated with these pressures have been addressed. Several wells have experienced annulus pressures in this field, where production is exclusively via gas lift. The causes of annulus pressures are discussed in the context of the mechanical configuration of the wells. An evaluation of the safety aspects and concerns associated with these pressures is then presented. Annulus pressure monitoring and operating procedures have been developed for use by offshore production personnel. These procedures contain a list of criteria which, when exceeded, require some type of action to remedy the problem in the well. Some of these criteria are based on a maximum pressure limitation for each well annulus. The derivation and application of these pressures is explained. The final section describes the changes made to the drilling and completion design of wells, in order to prevent or minimise the occurrence of annulus pressures. Introduction The North West Hutton oilfield, operated by Amoco (UK) Exploration Company ("Amoex") is located in the East Shetland Basin offshore UK, approximately 300 miles (483 km) north east of Aberdeen in licence block 211/27. Water depth is 475 ft (145 m). The reservoir is of Middle Jurassic Brent sandstone, and lies at an average depth of 11,500 ft (3 500 m) subsea. It is characterised by a series of tilted fault blocks and extreme lateral and vertical heterogeneity in its five major sand units. The field was discovered in 1975 and commenced production in April 1983 from seven pre-drilled wells, following the installation of a 40-slot fixed steel platform with two drilling rigs. Peak oil production of 86,000 BOPD (13 672 m3/d) was achieved the next month. Initially, reservoir pressure and oil production declined rapidly, and water injection was initiated in February 1984 to arrest this decline. In October 1984, gas lift was commenced to increase production rates, and by the end of 1985 all producing wells were on continuous gas lift. The current production rate from the field is approximately 20,000 BOPD (3 180 m3/d), and a continuous infill drilling program is currently underway to increase reserves and maintain production from the field. HISTORICAL OCCURRENCE OF ANNULUS PRESSURES The procedures for drilling and completing wells are designed such that no pressure should be seen on any well annulus. The exception is in gas-lifted wells, where gas is injected under pressure into the tubing-production casing annulus. Thermal expansion of the tubing and casing when wells are first placed on production may cause pressure to build up in one or more annuli; however these pressures should not recur once they are bled off and the well is in a normal production mode. P. 307^