The multiphase transportation of gas, crude oil, and brine without blocking of pipelines, caused by precipation of gas hydrates, waxes, and asphaltenes Is required to exploit marginal or deep offshore field economically. Since a kinetic Inhibition of gas hydrates to be the most promisisng way the research has now concentrated on hydrate formation kinetic. For both phases of the hydrate formation process, the nucleation phase and the growth phase, different parameters were determined with respect to multiphase now conditions. The duration of the induction period and the hydrate growth rate were determined u a function 01 now velocity and pi composition.
Gas hydrates are solid crystalline materials belonging to the group of inclusion compounds. They form when gas and water are brought together under pressure at suitable temperatures and are therefore a crucial problem in oil and gas transport and processing where they cause blocking of pipelines and field equipment. Typical countermeasures are the gas drying for the separation of a free water phase or inhibition with alcohol or glycols. Insulation or pressure reduction are in most cases not economical. In the current offshore oil and gas production a platform is used for the separation of the well stream consisting of crude oil, gas, and brine. With the trend going to greater depths, marginal fields, and polar regions the use of a platform quickly will become economical or technically impossible. An alternative to on-site separation is the multiphase transportation of the unprocessed well stream to the nearest separation facility through a pipeline directly from the production manifold at the sea bottom. Due to the prevailing pressure and temperature conditions one· will normally encounter -severe problems with gas hydrate, asphaltene, and paraffin precipation as well as with the formation of emulsions.