Schematic of oil and gas transportation from Nam Rong - Doi Moi to RP-1 of Rong oil field subsea pipelines from a marginal offshore oil field

Tóm tắt

In the last few years, Petrovietnam has discovered some marginal oil fi elds such as Nam Rong, Doi Moi, Ca Ngu Vang, Hai Su Den, Hai Su Trang, and Gau Trang, etc. Most of the oil and gas will be produced from the basement reservoir, but the oil and gas reserves from these fields are modest. The test results of wells during drilling showed that the maximum production rate from the wells of these fi elds is expected to be about 20,000 barrels/day (3,000 tons/day). The efficient development of these off shore oil fields will be problematic for the engineers. Oil production practices around the world show that, if the production of an offshore oil field is not more than 20,000 barrels/day, then the tie-in of the marginal fields to the nearest larger oil field will be a more effective way to produce the oil and gas.

In some cases, it will be a larger challenge because of the high pour point (~36oC) and high wax content (19 - 25%) of the crude oil produced from these fields. In addition, the wellhead temperature may be lower than the wax appearance temperature (WAT), which is in the range of 45 - 50oC. The offshore transportation of this oil and gas through long distance pipelines together with conditions of relatively low seabed temperatures (~21oC) will pose serious problems due to the deposition of paraffin wax.

The decision to tie-in smaller, marginal fields with high pour point and waxy crude to adjacent oil production platforms through subsea pipelines is very important for future oil production in Vietnam. This paper will describe the complexities and problems associated with oil and gas transportation from Nam Rong - Doi Moi oil field to the Rong oil field of Vietsovpetro.