A Laboratory Investigation Into The In-Situ Recovery Of Bitumen From An Oil Sand Formation Using Hot Water And Naphtha
Authors: Harris P. , Toma P. , Livesey D. 
Published: March 2010

A laboratory investigation into the recovery of bitumen using hot water and naphtha was carried out in 1981 and 1982 by the Alberta Research Council under contract of Texaco Canada Resources Ltd.

An oil sand formation which was assumed to contain a highly permeable zone exposed to a hot water-naphtha injection was simulated in the laboratory using a Hassler type cell. The cell could accommodate a core 9.2 cm in diameter and 17.8 cm long. An axial, 13 mm diameter communication path was filled with frac sand, and hot water and naphtha flowed through at a known rate.

The study presented in (his paper aims to offer a simple estimation of the economics of a hot water-naphtha process. Data collected from ten runs were processed in order to calculate the most characteristic parameters for the process. A multiple linear regression technique was applied to obtain simple linear equations subsequently used for the optimization study. An analogy between rates of production obtained in the physical simulator and those obtained in the field was heuristically assumed. This assumption permits the extension of the study to a field process. Within the limitations of the study the linear model approximated the real data and, as might be expected, recommended as high an injection temperature as possible regardless of the amount of naphtha added.

Introduction

Diluent naphtha and other light hydrocarbons are being considered as potential additives to stearn and hot water in order to enhance the in-situ recovery of bitumen from oil sand reservoirs(1, 6). Insufficient information regarding the use of the naphtha as an additive in a hot water process required a dedicated laboratory study.A physical simulator was extensively used to provide information on the recovery process.

Experimental

An oil sand formation*, containing a highly permeable zone exposed to a hot water-naphtha injection was simulated in the laboratory using a pressurized Hassler-type cell as illustrated in Figure 1. The system consisted of a reconstituted core of surface-mined Athabasca oil sand contained within a deformable lead sleeve. The diameter of the core was 9.2 cm and the length was approximately 17.8 cm. An axial communication ath was constructed by drilling a 13 mm diameter hole and filling it with clean water-wet frac sand (10 – 20 mesh). A pressure vessel containing the oil sand sample simulated a 90 m overburden pressure through the use of nitrogen gas at 2.1 MPa. A constant injection rate of 3.0 kg/h of hot water and naphtha was used throughout the series of experiments. Differential pressure across the core was continuously recorded.

The produced fluids, consisting of free bitumen, a bitumen-water emulsion and naphtha, were collected and analyzed. A back pressure control valve prevented flashing of the produced fluids.

The flow rate was chosen as a compromise between realistic field data and the principal function of the laboratory facility, which was to rapidly screen a large number of variations on a particular recovery scheme.