Ardian Nengkoda, Abdulla Harthy, Wael Afify Taha, Hendrikus Reerink, Moh’d
Hajri, Petroleum Development Oman, Hase Alfred, Champion Technology, Lamda
Muchjin, Crescent Petroleum, Supranto, Suryo Purwono, Gadjah Mada
Currently, there are more than 10 oil producing station, in both North and
South area operation of Petroleum Development Oman, which facing a unique gas
hydrate problems. Most of these wells are producing by the support of gas lift.
Therefore, it is very important that the gas lift network is kept optimally
operating to maintain the intended production. The ambient temperature in
Sultanate of Oman desert drops to as low as 5°C during the coldest 3 months in
winter, when hydrates form in several gas lift lines. This causes affected
wells to cease production and results in unscheduled deferment. So far, the
problem was partly controlled by the use of methanol as hydrate inhibitor (a
proven method used worldwide to restrict gas hydrate formation), however there
are resulted many issues mainly HSE associated with the use of methanol. The
main objectives of this project are to look the other chemicals alternative as
hydrate inhibitor – move from methanol to another cost effective and safe
chemical inhibitor and the goal is to ensure that the system is adequately
inhibited against hydrate formation and that inhibitor injection is optimized.
The second goal is to develop a warning system should hydrate start to form
(prior to hydrate build up and pipeline blockage). The paper also defines
laboratory testing as mandatory requirement to test an alternative hydrate
inhibitor and practical facilities up grade.
For many years, hydrate formation is a substantial problem oil and gas
production, once plugs have formed; there are limited possibilities for
removal. Common hydrate problem occur at sub sea pipeline, top side facilities
or cold environment. Since the 1970's, the oil and gas industry has faced
increasing costs associated with inhibition of gas hydrate formation, due to
the development of offshore gas reservoirs. Gas hydrates are likely to form in
subsea flowlines unless the water is removed down to the lowest dew point
encountered, highly effective insulation is in place, or inhibitors are used.
The first option is difficult when supersaturated condensates exist in the
flowline even after the gas phase is stripped to saturation levels. Stripping
condensate completely of water is prohibitively expensive and effective
insulation is beyond current economic limits. Therefore, the most effective
solution appears to be the use of inhibitors. Generically, there are two kinds
of hydrate inhibitors: thermodynamic inhibitors, and the more recently
identified low-dosage inhibitors.