On the Physical Properties of Oil from the Lomovoye Field
Abstract Generated abstract
This paper reports laboratory measurements of the physical properties of oil from the Lomovoye field in northern Tomsk Oblast, based on ungassed samples from well 201 under formation conditions of 274 ati and 106°C. Using standard reservoir oil analysis and viscometric measurements, the study determines saturation pressure, gas content, volume coefficient, density, compressibility, shrinkage, and viscosity in ungassed and partially degassed states. The oil is found to be broadly similar to other Tomsk Oblast oils, but with high gas content and a substantial volume coefficient, while viscosity measurements show lower viscosity for ungassed oil than for partially or fully degassed oil, increasing with pressure at constant gas saturation and decreasing with temperature.
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ON THE PHYSICAL PROPERTIES OF OIL FROM THE LOMOVOYE FIELD
G. N. CHERTENKOVA
(Presented by Professor A. V. Aksarin)
The Lomovoye oil field is located in the northern part of Tomsk Oblast. Its oil-bearing capacity is associated with bed Yu-1 (Vasyugan suite). The oil for analysis was sampled from well 201 in the bottom-hole zone and delivered to the laboratory of oil-reservoir physics of the Tomsk Polytechnic Institute in an ungassed state. The formation pressure measured in this well proved to be 274 ati; the formation temperature was 106°C.
The oil was studied on a UIPN-2M apparatus according to the method described by V. N. Mamuna and others [1]. The principal physical properties of the oil from the Lomovoye field are given in Table 1. In its physical properties, the oil of this field differs little from
Table 1
Physical properties of oil from the Lomovoye field, Tomsk Oblast
(sample taken from well 201; formation pressure 274 ati; formation temperature 106°C)
| Parameters, units of measurement | Sample No. 1 | Sample No. 2 | Mean values |
|---|---|---|---|
| Date of sample taking | May, 1972 | May, 1972 | |
| Saturation pressure, ati | 128 | 126 | 127 |
| Compressibility coefficient of oil, 1/at | 15.5·10⁻⁵ | 16.56·10⁻⁵ | 16.03·10⁻⁵ |
| Gas content referred to unit volume, m³/m³ | 113.89 | 123.99 | 118.94 |
| Gas content referred to unit weight, m³/t | 135.74 | 147.53 | 141.63 |
| Volume coefficient | 1.365 | 1.376 | 1.370 |
| Shrinkage, % | 27.3 | 26.3 | 27.0 |
| Density of separated oil, g/cm³ | 0.839 | 0.840 | 0.840 |
| Density of formation oil, g/cm³ | 0.722 | 0.727 | 0.725 |
| Gas density, g/liter | 1.292 | 1.294 | 1.293 |
| Mean gas solubility coefficient, cm³/cm³·at | 0.890 | 0.984 | 0.937 |
| Viscosity of ungassed oil under formation conditions, centipoises | 0.61 | 0.63 | 0.62 |
| Viscosity of separated oil under surface conditions, centipoises | 5.49 | 5.49 | |
| Final separation pressure, mm Hg | 760 | 757 | |
| Final separation temperature | 20°C | 20°C | |
| Date of completion of analysis | 5 June 1972 | 22 June 1972 |
oils from other fields of Tomsk Oblast. Nevertheless, it should be noted that it belongs to the group of oils with a high gas content, exceeding 100 cm³/cm³, and a considerable volumetric coefficient—1.370.
Special attention in the study was given to the viscosity of the oil in the ungassed and partially degassed states. This property was studied on a VVDU viscometer at several temperatures and pressures. The results of these studies are given in Tables 2 and 3.
Table 2
Results of the study of the viscosity of oil from the Lomovoye field
in the ungassed state (1st sample)
| Pressure at which viscosity was determined, \(ati\) | 23°C | 30°C | 40°C | 60°C | 80°C | 106°C (reservoir temp.) |
|---|---|---|---|---|---|---|
| 274 (reservoir pressure) | 0.75 | 0.74 | 0.71 | 0.67 | 0.62 | 0.61 |
| 200 | 0.74 | 0.72 | 0.70 | 0.65 | 0.61 | 0.59 |
| 150 | 0.72 | 0.71 | 0.69 | 0.62 | 0.59 | 0.57 |
Table 3
Results of the study of the viscosity of oil from the Lomovoye field (well 201)
in the partially degassed state (second sample)
| Degassing pressure, \(ati\) | Pressure at which viscosity was determined | 25°C | 40°C | 60°C | 80°C | 106°C (reservoir temp.) |
|---|---|---|---|---|---|---|
| 50 | 274 \(ati\) (reservoir pressure) | 1.09 | 0.98 | 0.91 | 0.86 | 0.85 |
| 50 | 200 \(ati\) | 1.08 | 0.96 | 0.90 | 0.85 | 0.84 |
| 50 | 100 \(ati\) | 1.05 | 0.95 | 0.89 | 0.84 | 0.82 |
| 50 | 60 \(ati\) | 1.03 | 0.94 | 0.88 | 0.82 | 0.81 |
From an analysis of these tables it is evident that completely ungassed oil, at the same temperatures and pressures, proves to be less viscous than partially degassed oil. Fully degassed oil, by comparison with them, proves to be several times more viscous. An increase in pressure at constant gas saturation is accompanied by an increase in viscosity; an increase in temperature, by a decrease in viscosity, as has been noted by many investigators.
LITERATURE
- V. N. Mamuna, G. F. Trebin, B. V. Ulyaninskii. Experimental Study of Reservoir Oils. GOSINTI, 1960.