Laboratory Studies of Water Treatment for Thermal Recovery Use
Authors: Carlberg B.L. , Casad B.M. 
Published: December 2007

American Institute of Mining, Metallurgical and Petroleum Engineers, Inc.

This paper was prepared for the 42nd Annual Fall Meeting of the Society of Petroleum Engineers of AIME, to be held in Houston, Tex., Oct. 1–4, 1967. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor of the appropriate journal provided agreement to give proper credit is made.

Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussion may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines.

Numerous hot water or steam injection projects have been restricted or prevented entirely by a lack of suitable fresh water. Fresh water supplies may become even more restricted in the future. These studies, which are continuing, should provide some of the water treatment answers necessary to permit use of waters and brines now considered unsuitable as feed to conventional heaters and steam generators.

The pilot steam generator used in this research was designed to provide steam at up to 600 degrees F with heat transfer of at least 15,000 BTU's per ft(2) per hour. All steam is confined to 1/2 or 3/8 inch tubes. Areas of study include corrosion and scale deposition as well as treating processes for their control.

The first studies were to determine the effect of an EDTA compound on corrosion in a system of 500 degrees F 80% steam. The presence of the EDTA compound, in any concentration, increased corrosion rates. Above 25 ppm EDTA the attack became severe with pitting at points of turbulence. The effect was the same whether the compound was in the free or chelated form. If EDTA is to be used 10 ppm active ingredient is considered as the safe upper limit.

The present work is concerned with investigating various processes and compounds for prevention of scale deposition. Several high molecular weight polyacrylates have been found to inhibit deposition of calcium sulfate at 350 degrees F and 70% quality. Continuing work along this line is expected to allow the use of many oil field waters as feed to steam generators.

Introduction

Thermal recovery projects, notably hot water and steam injection, to stimulate the production of oil have emphasized a general lack of brackish water treating procedures for elevated temperatures. There has been extensive research on the problems associated with desalting of brackish and ocean waters. Some of this information is pertinent to the problems associated with thermal recovery. There are, however, three significant differences. First, even in the distillation processes desalting temperatures rarely exceed 250 degrees F while 500 degrees F and higher are common in thermal recovery.