Problems in Gas Hydrates: Practical Guidelines for Field Remediation

Abstract

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractNatural gas hydrate formation is a costly and challenging problem for the oil and gas industry. In recent years, two new families of chemical additives have been commercially developed to prevent hydrate plugging problems in production lines. This approach is commonly known as low-dose inhibition, and the two families are kinetic inhibitors and antiagglomerants. Evolution of these new products is proceeding at a rapid pace, in order to meet goals of covering a greater range of operating conditions and finding an economically and environmentally attractive alternative to thermodynamic inhibition. Successful deployment of low-dose inhibitors depends on an appropriate selection of inhibitors and a complete understanding of the system. Based on a synthesis of available literature on application of low-dose inhibitors to hydrocarbon processing equipment and handling facilities, this paper describes a methodology for designing a deployment strategy. This guide provides a systematic approach to aid production engineers in deploying low-dose inhibitors in existing facilities and new developments. An easy-to-follow flow chart is given. The information provided in this article was compiled from published data, and experience provided by several companies in the oil and gas industry.

AdaBoost Metalearning Methodology for Modeling the Incipient Dissociation Conditions of Clathrate Hydrates

“…One of the most commonly used methods is the injection of inhibitors. Typically, there are two main categories of inhibitors: low-dosage hydrate inhibitors (LDHIs) and thermodynamic inhibitors . Thermodynamic inhibitors can shift the stability zone of the hydrate to low temperatures and/or high pressures.…”

Polymer Flooding in Artificial Hydrate Bearing Sediments for Methane Gas Recovery

“…In the thermal stimulation method, severe heat losses have been accounted which can lead to several other operational challenges affecting energy efficiency. ,− Although depressurization is relatively an energy efficient process, the hydrate may reform during methane gas production and choke the wellbore and production tubing. ,,, Also, the depressurization process may weaken the formation. , Alternatively, hydrate inhibitor injection can be a potentially efficient method due to its ease of operation. This process can have several advantages such as increased energy efficiency, decreased risk of hydrate reformation, and helps in maintaining the formation stability by altering the properties of the wellbore and reservoir matrix. ,, Generally, two types of inhibitors are used: thermodynamic inhibitors and low dosage kinetic hydrate inhibitors (LDHI). ,, The thermodynamic inhibitors shift the phase stability of hydrate to higher pressure and lower temperature thereby dissociating hydrates. LDHI can be categorized into two parts: antiagglomerate (AA) and kinetic hydrate inhibitors (KHI), where AA prevents the agglomeration of small hydrate particles into a bigger form, while KHI prevents the hydrate formation for a longer duration. ,, The common thermodynamic inhibitors are monoethylene glycol, diethylene glycol, triethylene glycol, and methanol, which are mostly used to prevent hydrate formation and deposition in pipelines thereby resolving flow assurance issues. ,− Some dissolved salts (for e.g., NaCl, CaCl 2 , KCl, NaBr) are also used as thermodynamic hydrate inhibitors. ,, …”