Gas hydrates are a major challenge in oil and gas production systems and hydrate inhibitors are typically injected in large quantities to avoid potential pipeline blockage.

The hydrate inhibitor injection rates generally remain fixed for long periods and are usually determined based on a number of parameters including, the hydrocarbon composition, worst case operating conditions, inhibitor loss to hydrocarbon phases, water production rate and so on.

Currently there is no means of measuring and optimising inhibitor injection rates in response to changes in production parameters. This can result in over inhibition, which is costly and carries a number of HSE risks or more importantly, under inhibited systems, which can result in hydrate blockages.

In July 2007, ITF launched a Joint Industry Project (JIP) with support from five major oil and gas operators. The HydraCHEK device was developed as part of the project in conjunction with Hydrafact.

HydraCHEK provides the actual concentration of hydrate inhibitor and salt through downstream analysis of produced water samples. Combined with operating parameters, the output data allows the operator to continuously monitor and optimise inhibitor injection rates.

Unique and highly innovative, HydraCHEK is revolutionising the way in which hydrate risks are managed and gives operators confidence that a system is not at risk of hydrate formation that has not been previously possible.

Data Capture and Analyses

HydraCHEK measures the acoustic velocity, electrical conductivity and temperature of a produced water sample and an artificial neural network (ANN) is used to correlate the results and develop robust calibrations for detecting different organic hydrate inhibitors and their concentrations.

This output data is then fed into a customised version of Hydrafact’s thermodynamic gas hydrate prediction model HydraFLASH. Combined with the hydrocarbon composition and system pressure/temperature data, the hydrate stability zone and hydrate safety margin can be determined at the push of a button.

Optimising Inhibitor Injection Rates

HydraCHEK can be used to constantly monitor the inhibitor concentration in a system and ensure a suitable hydrate safety margin is maintained relative to operating conditions.

Using HydraCHEK, inhibitor injection rates can be continuously monitored and adjusted to avoid hydrate blockage due to under-inhibition or costly wastage as a result of over-inhibition a system.

Rapid and Accurate Inhibitor Concentration Measurements

To determine salt and hydrate inhibitor concentrations by conventional methods requires a number of different, time consuming tests (e.g. GC, titration, gravimetric) and the associated equipment. In contrast, HydraCHEK offers equal or in most cases better accuracy in a very simple and rapid direct measurement, saving both time and cost for the operator.

To date HydraCHEK been successfully implemented by the participants of the JIP and is in regular use by a number of major operators worldwide.

HydraCHEK has a number of benefits, which include the speed and ease of use of the device, the ability to monitor and optimise hydrate inhibitor injection rates and also the ability to work with various salts and inhibitors (MEG, methanol, KHIs, AAs).

HydraCHEK helps mitigate hydrate risks, reduce operating costs, and provides a rapid and highly accurate means to measure inhibitor concentrations. The tool is flexible, user friendly and can be tailored to suit different production systems. It can also be used for monitoring other chemical streams, e.g., umbilicals, gas dehydration & inhibitor regeneration units.