Gas hydrate inhibition is a serious concern for operators who produce or transport natural gas at pressure and temperature conditions favorable for hydrates formation. As production goes into deeper water, hydrate control grows in importance. Ideally, operators want total hydrate control without the problems associated with Thermodynamic Hydrate Inhibitors (THI), mainly methanol and/or Low Dose Hydrate Inhibitors (LDHI). Past laboratory studies and field experience indicated that hydrate inhibition synergy is gained through the combination of Thermodynamic Inhibitors and Kinetic Inhibitors (KHI). This is termed a Hybrid Hydrate Inhibitor (HHI). Because of the performance, logistical and cost drivers presented by the use of methanol, any alternative approach would have to consider these three factors.
Detailed studies were performed on several mixtures of polymeric and non-polymeric KHI, and THI to find best performing combinations of hydrate inhibitors. The objective of the study was to provide all of the benefits of the existing technology with improved performance, improved logistics and at a cost not to exceed hydrate prevention with methanol. It was uncovered that some KHIs combined together supplement each other to offer synergistic performance for significantly lower cost than single KHI products. The work to be presented resulted in discovery of few KHI/KHI/THI combinations that outperformed any previously used product.
Oil and gas industry is continuously looking for more cost-efficient and safer technologies. This work offers another improvement in flow control assurance.
Laboratory studies and past field experience indicated that hydrate inhibition synergy is gained through the combination of Thermodynamic Inhibitors (THI) and Kinetic Inhibitors (KHI) [1]. This is termed a Hybrid Hydrate Inhibitor (HHI). Because of the performance, logistical and cost drivers presented by the use of methanol, any alternative approach would have to consider those three factors. The performance has to do with hydrate dissolution in the event a hydrate formed during operations. A Kinetic Inhibitor (KHI) can prevent hydrates formation but cannot dissolve already formed hydrates. Anti-agglomerant inhibitors (AA) allow hydrates to form but keep the hydrate particles dispersed in the fluids. The logistical has to do with pump sizing; i.e. conventional Low Dosage Inhibitor (LDHI) applications require new pumps and configurations.
Potential synergy in gas hydrate inhibition between polyether amines (PEA) and polymeric type kinetic hydrate inhibitors (PHI) has been reported before [2, 3]; however, this phenomenon was not studied thoroughly. PHIs are very costly chemicals, about five times more expensive than PEAs. The cost of methanol is far less than specialty LDHI chemistry.
