The gas to shore project must consider an optimum path to shore

Jan 14, 2021 Letters

Dear Editor,

Guyana government is increasingly considering a gas to shore project to support the growing energy needs, faced since mid-2015. According to previous reports, ExxonMobil offered in 2018 to bring 30 million cubic feet per day (MMScfD) of gas to shore, to meet Guyana’s energy needs. Private sector has shown interest in the project, as thermoelectric generation, domestic, and vehicle gas consumption could translate into a growing business.
Since production startup, producing gas oil ratio (GOR) has been consistently increasing, at an average rate of 12% to 14% per month, from around 450 Scf/Stb initially, to around 1.150 Scf/Stb more recently. Although doubtful, assuming December 120.000 BPD production estimate informed by Exxon was correct, the equivalent gas production should be at present in the neighbourhood of 110 to 130 MMScfD from 30 to 40 MMScfD initially.

As previously mentioned in February’2020, both Liza and Payara assets [https://kaieteurnewsonline.com/2020/02/03/guyanas-offshore-facts-risks-and-challenges/] are mainly volumetric, meaning there is no natural pressure support, demanding fluid injection to compensate for the energy lost during production. But the case of Liza seems particularly complex, as it apparently was initially thermodynamically placed exactly at the saturation point, prompting segregated gas production since project inception.
Further complications could rapidly arise for the Liza production, as reservoir energy rapidly dissipates in spite of gas recycling/injection, as fill up time, and/or uncontained injected fluids leaked outside the reservoir, work against pressure maintenance. This is precisely the reason why the GOR has been consistently increasing, and expecting to continue to expand with time.
Liza project only includes three gas injectors. Disposed gas volume into the reservoir is limited besides by the number of injectors, by the injectivity rate, and the formation fracture pressure. Exceeding these latest parameters could lead to complex environmental hazards. Although injection rate tends to diminish with time, for the Liza project gas injection rates could top from 8 to 14 MMScfD per well, equating into a maximum gas injection volume of 24 to 42 MMCsfD.
Besides the gas that is being utilized as process feedstock, the rest is considered a “liability” and a cost centre for Exxon. If the above assumptions are correct, current Exxon gas liability from Liza asset amounts between 50 and 60 MMScfD. This is the volume of gas that Exxon actually could be forced to invest additional unexpected funds into, to be able to reutilize it, unless the PSA allows them to fully flare it.
For the case of Liza Phase II some 15 injection wells will be considered, allowing more room to disposed produced gas through 6 gas injectors. In the meantime, as Exxon is not willing to expose any additional unplanned capital, is looking for ways to lead Guyana into a possible dead end, where the country will be forced to finance their expenses and costs, selling the gas to shore project as a solution to Guyana, when actually is a solution to their own growing problems. Guyana should patiently await, and at the same time enforce the environmental law to limit Exxon’s flaring and pollution practices.
The gas to shore project must consider an optimum path to shore, to allow for future interconnection of multiple fields through a gas ring and not a single route. As more assets are developed, and mature, more gas volumes will be available to satisfy not only Guyana energy needs, but perhaps some of its neighbours.

Millan Arcia Einstein
Senior Upstream Oil & Natural Gas Global Adviser and Subject Matter Expert.

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