Hydrates are one of the most serious issues in deepwater production systems. Remediation operations are usually time-consuming and expensive, especially if the low-cost methods using the existing infrastructure e.g. injecting thermodynamic hydrate inhibitor (THI) at the vicinity of the hydrates are not feasible or have been tried without any success. Nonetheless, in most cases, should the incident occur, the benefits of removing the blockages and resuming production outweighs the cost of intervention. There are a variety of techniques for hydrate remediation such as using chemicals, mechanical, depressurization and thermal methods. Hydrate remediation operations usually constitutes of a method whereby the ins-situ temperature or pressure conditions are changed in a way that the condition is outside hydrate formation region (HFR). Alternative methods are using THI's to shift the hydrate curves to the left so that the hydrates are dissociated at a lower pressure at the same temperature.

One of the scenarios that carries a relatively high level of hydrate blockage risk is the initial start-up of a brand new well. This work describes a hydrate blockage incident in a West African deep-water infill well tubing, and associated attempts in remediation. The remediation work included forming a team of experts to investigate the root cause of no-flow during the initial start-up, propose the feasible methods to unblock and re-establish the flow using the existing infrastructure such as methanol injection from the wellhead. However, given that methanol could not reach the depth at which the blockage(s) were formed, a Hydrate Remediation Skid (HRS) was hired from the relevant contractors, adequate system isolations were made and depressurization carried out which eventually removed the hydrates and unblocked the production tubing. There has been a number of lessons learnt from this remediation operation which can be extended to other hydrate remediation activities with minor adjustments.

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