Abstract

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.

Introduction

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.

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