Background

The Sudan export pipeline from Heglig to the port Sudan has a designed throughput of about 220'000bpd and the desired throughput is now about 240'000bpd. In order to achieve this increase in throughput, two methods can be adopted. One is to construct new pump stations to improve the hydraulic condition of the pipeline. But that involves a huge equipment investment and operation expenses. Considering the unpredictable yield of the oil field, there is arisk of wasting money. Another method is to utilize drag reducing agent. Which only needs a small amount of money every year. When the DRA is injected into this pipeline, the anticipated effect will exhibited just within a few days. And when the throughput is reduced to a normal level, all that should t\be done is only to stop the injection equipment. Without doubt, adopting DRA is the best choice. So the industrial test of using EP-W203 DRA in Sudan Pipeline was implemented during July 29 to August 03 in 2001.

Basic test conditions

The basic operation parameters without DRA injection are as follows:

  • PS-01(pump station#1)
    • Suction pressure: 500kPa
    • Discharge pressure: 9600kPa
    • Temperature of the crude oil: 69°C
    • Flow rate: 220'000bpd or lower
  • PS-02(pump station#2)
    • Station pressure: 3356kPa
  • PS-03(pump station#3)
    • Suction pressure: 304kPa
    • Discharge pressure: 7223kPa
    • Flow rate: 205'000bpd

The industrial test was carried out in two stages, as follows:

  • Flow rate controlled and allowing pressure to decrease at PS-01.
  • discharge pressure controlled and maximizing the flow at PS-01.

DRA EP-W203 injection skid

Observations and conclusions

The test duration of drag reduction was 86 hours, and the average concentration of DRA in the crude oil was 19.3 ppm. The discharge pressure of PS-01 was reduced from 9600 kPa to 8848kPA. The R.P.M of PS-01 was reduced from 9600kPa to 8848kPa. The R.P.M of PS-01 was reduced from 738 to 711. The drag reduction of the segment from PS-01 to PS-02 was 21.14%, corresponding to the possible throughput increase of 15%. And the drag reduction of the segment from PS-02 to PS-03 was about 2.12%, no evident drag reduction has been observed so far.

The test duration of throughput increase was 35 hours. And the average concentration of DRA in the crude oil was 23.80 ppm. The throughput of the pipeline segment from PS-01 to PS-03 is increased from 220'000 bpd TO 228'000 bps, corresponding to a throughput increase of 5.13%.

Based on the main observations above, it is suggested to provide DRA injection points at two places: one at PS-01 and second at PS-02.

The readings during the test were recorded by MCC and are enclosed Attachment.

Economical evaluation

Even under a throughput increase of 5.0% with one DRA injection point at PS-01 ,more than 3'850'000bbl of extra oil will be transported and US$77 million will be saved and only at an expense of about US$2.5 million every year.

If the throughput has been increased by 12% with two DRA injection points at PS-01 and PS-02under the basis of 220'000bpd, more than 9'240'000bbl of extra oil will be transported and US$185 million will be saved and only at an expense of about US$5.8 million at the most every year .

In addition, the need of pump stations extension will be eliminated if DRA is applied to the pipeline. That will save huge investment and operation expenses in the future.