Defoaming Agents for Increased Oil Production Rates of Foamy CrudesLaboratory Screening Tests and Field Results
Authors: Fallin Steve , Sharp Shelby P. , Wolfe Jim L. 
Published: December 2007

Defoaming Agents for Increased Oil Production Rates of Foamy CrudesLaboratory Production Rates of Foamy CrudesLaboratory Screening Tests and Field Results

In the East Velma field of southern Oklahoma defoaming agents have resulted in substantial increases in productivity. Of the 43 wells field-tested with dimethyl silicone, 21 successful tests have yielded a total production increase of 1,360 BOPD.

Introduction

Since the East Velma field, located in southern Oklahoma, was unitized in the early 1960's, production has increased substantially. Gross operated production increased from 7,850 BOPD during the last half production increased from 7,850 BOPD during the last half of 1963 to 20,710 BOPD in late 1969. Relatively large investments were made for various types of lift equipment, including beam pumping units, hydraulic pumping equipment, and electric submersible pumps. pumping equipment, and electric submersible pumps. In certain cases, the equipment failed to pump larger volumes of crude, and monitoring data indicated substantial fluid levels above the pump. In late 1967, in an effort to lower pumping fluid levels by depressing foam columns, defoaming agents were first tried in the East Velma field. The objective was to either verify or eliminate the image of high working fluid levels. The defoaming agents were successful in lowering fluid levels to a certain extent; however, during the period immediately following the use of defoamers for fluid column depression, an increase in production was noted. After analyzing data obtained during the tests, a field-wide testing program was initiated to determine if the initial production increases could be reproduced and economically sustained over a period of time. Concurrently, laboratory tests were started to determine if the most effective defoaming agents were being used.

Description of Defoaming Compounds And How They Work

There are many commercially available defoaming agents. Examples of several family types are phosphate esters, metallic soaps of fatty acids, and organic phosphate esters, metallic soaps of fatty acids, and organic silicone compounds. The organic silicone compounds are the most ideally suited for use in crude oil as defoaming agents for the following reasons.They are effective at concentrations of only a few parts per million.They are chemically inert and do not contaminate oil.They are soluble in the lighter ends of crude fractions.They exhibit only sought change of properties over a wide range of temperature.

In foamy crudes, gas is broken up into small bubbles of various sizes separated from each other by a thin oil film. These films are often so tough and resilient that the entrapped gas is not easily released. Oil does not foam by itself; however, when a very small quantity of surface-active agent is added to the oil that is being agitated in the presence of gas, foam is generated. Wellbore foaming of oil, therefore, requires two things: the presence of a surface-active agent in the oil and availability of a gas. Some oils are known to contain natural surface-active agents and some may become surface active by mixing with oilfield chemicals. (Velma crudes have been found to be naturally surface active.) The stability of the resulting foam depends upon the nature of the oil and the nature and concentration of the surface-active agent.

JPT

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