Aquathermolysis and Sources of Produced Gases in SAGD

Abstract

It has long been known that heavy oil and bitumen recovery by SAGD and CSS processes is accompanied by significant production of acid gases, as well as solution gas. Since the old laboratory studies of aquathermolysis from the 1970's and 1980's, there has been considerable development in the knowledge concerning production of methane and acid gases from Athabasca, Cold Lake, Peace River, Venezuela and Utah oil sands. It is found that both GOR and gas composition may vary with the deposits concerned. There is considerable divergence of opinion about the chemical origin of some gases, notably carbon dioxide. This affects the methods of control that may be available in operating individual reservoirs, and the matter is discussed. Also discussed will be the means of taking advantage of aquathermolysis phenomenon. It has been shown that both the GOR and gas composition of a SAGD project can be calculated from first principles. This permits estimation of the daily throughput of hydrogen sulphide and therefore allows a prediction or control of the requirements for sulphur recovery. The control of scale in SAGD plants has also been achieved by application of the current state of knowledge. Finally, there are implications for hydrogen sulphide release during loss of well control, an important regulatory aspect.

Combining Steam and Flue Gas as a Strategy to Support Energy Efficiency: A Comprehensive Review of the Associated Mechanisms

“…The aquathermolysis phenomenon involves a series of chemical reactions between the organosulfur compounds of crude oil, water, and certain minerals in the rock acting as natural catalysts in a temperature range between 250 and 300 °C. The sequence begins with the breakdown of the organosulfur compounds of the crude oil through hydrolysis reactions that produce H 2 S. R  C H 2  S  C H 2  normalR ′ ↔ R  C H 2  S H + H 2 O ↔ R C H 2  O H + H 2 S This is followed by a reorganization of the unsaturated alcohols and the formation of aldehydes, which then give way to the formation of carbon monoxide R  C H 2  O H ↔ R  C H 2  C H O − ↔ R C H 3 + C O Carbon monoxide undergoes water–gas shifting reactions forming hydrogen and carbon dioxide C …”

Studies of Aqueous Hydrogen Sulfide Corrosion in Producing SAGD Wells

“…In SAGD, a process known as aquathermolysis [3,4] takes place and leads to the formation of aqueous acidic gases, including H 2 S and CO 2 , both of which are known to be highly corrosive when dissolved in water. Such conditions can be present in SAGD wells, specifically in the annulus of production wells where these gases are able to concentrate in a low flowing or stale environment.…”

“…Tubular and completion components and materials commonly used in SAGD are shown in Table 1.1: and hydrogen (H 2 ) are also produced. The ratio and quantities of these gases can vary from site to site depending on reservoir properties, production conditions, and asset age [4].…”

Influence of Metal Oxides and Their Precursors on the Composition of Final Products of Aquathermolysis of Raw Ashalchin Oil

“…Thermal and hydrothermal transformations of organic matter and petroleum hydrocarbons in a water vapor medium in a closed system are considered in the scientific literature as one of the methods for modeling processes of hydrocarbon conversion during generation, migration, production by thermal steam extraction methods, as well. First experimental studies on high-temperature transformations of petroleum hydrocarbons in the presence of water vapor and mineral compounds were carried out in the early 1970s and 1980s and called aquathermolysis [28]. Harald Thimm's work was mainly focused on gas formation.…”