DETAILED ASSAYS CONDUCTED ON VIETNAMESE CRUDE OILS

Pham Quang Du
Petro Viet Nam
Ho Chi Minh City

More oil property data, in the form of recent crude oil assays, have been made available for two Vietnamese crude oils, Bach Ho (White Tiger) and Dai Hung (Big Bear).

Crude oil data presented earlier (OGJ, Nov. 6,1989, p. 39) gave limited properties of the crudes, which are from the Miocene formations.

Further analyses have been conducted on Bach Ho crude from the Oligocene formations. Production from Oligocene is far more representative of the oils produced from the Bach Ho field and marketed worldwide.

Currently, Bach Ho is the only producing field. Dai Hung is expected to be in production during the next few years.

Bach Ho is currently producing at the rate of 20,000 b/d. That figure is projected to grow to 100,000 b/d by 1992 and to 120,000 b/d by 1995.

Detailed assays of both crude oils are presented here.

NAPHTHA PROPERTIES

A comparison of the naphtha cuts of both crude oils shows that the paraffin content, particularly of n-paraffin, of Dai Hung is much lower than that for Bach Ho (Table 1). But the aromatic content of Dai Hung is much higher than that for Bach Ho.

The difference between hydrocarbon group distributions of the naphtha cut compositions of Bach Ho and Dai Hung has a primary importance for gasoline-cut processing. Catalytic reforming of the gasoline cuts will be different for the two crudes.

The distribution of hydrocarbon groups of the Vietnamese crudes, particularly the distribution of n-paraffins, also has a large effect on transportation and processing of the these highly waxy crudes.

Fig. 1 shows the n-paraffin distribution of the two crude oils. It is clearly seen that for the naphtha cut, n-paraffin is higher for Dai Hung than for Bach Ho.

But for the diesel (gas oil) cut, the n-paraffin content (C12-C18) is similar for both crudes at about 9.5 wt %. With such a high n-paraffin content in the diesel cut, it is highly advisable to expect paraffin separation processing to decrease the pour point of the diesel and to supply the n-paraffins as raw material in petrochemical processing.

High-value petrochemical products could be: Sodium alkyl sulfonate, di-carboxilic acid, and cyclo pentadecanone.

Fig. 2 compares the paraffin distribution of the Vietnamese crude oils to the distributions of Taching (China), Minas (Indonesia), and Bombay High (India). Complete assays of these crudes can be found in OGJ, Sept. 5, 1983, pp. 144 and 148, and OGJ, Nov. 21, 1983, p. 78.

Although Minas, Taching, and Bombay High are of high paraffin contents and have similar pour points, their n paraffin distributions are completely different (Table 2). This greatly affects pour point depressant utilization.

For example, the IFP pour point depressant TPE101 used at 500 ppm can lower the pour point of Bombay High to 12 C. from 30 C., according to IFP. But the same depressant used at 3,000 ppm in Bach Ho, reduces the pour point to only 27 C. from 33 C.

However, two pour point depressants, Chem Link P 7599 and P-7590, used at 500 ppm are able to reduce the pour point of Bach Ho to 21 C. from 33 C., according to experiments at Vietsovpetrol in April by Chem Link.

The differences in the effects of the IFP and Chem Link depressants when they are applied to Vietnamese crude oils show different mechanisms of action of chemicals on the n paraffin distribution of the crudes.

In conclusion, the study of hydrocarbon group distribution, particularly the n-paraffin distribution in Vietnamese crude oils, has an important practical importance in the selection of the proper additives for transportation and production, but also for determination of processing orientation in view of obtaining high-value raw materials for petrochemicals production.

BACH HO (WHITE TIGER) VIET NAM

Floating storage in South China Sea southeast of Ho Chi Minh city.

(See original document for statistics)

ACKNOWLEDGMENT

The author thanks J.P. Durant of IFP and his colleagues for their permission to use the n-paraffin distribution data on the crude oils used in the comparisons.