* Gas exporting countries hold summit in Bolivia this week
* Energy ministers from countries with 70 pct of world gas reserves to discuss policy
* Executives from major gas producers meet during forum (Updates with event kickoff, quotes, background)
By Marianna Parraga and Alexandra Alper
SANTA CRUZ, Bolivia, Nov 21 (Reuters) - Top officials of major gas producing countries are meeting this week in Bolivia to weigh how to shore up prices that have been hammered by expanding supplies of the fuel that are giving global buyers greater sway over purchase and contract terms.
The Gas Exporting Countries Forum (GECF), which aspires to be the OPEC for natural gas suppliers, kicked off the event on Tuesday with calls for cooperation. The four-day meeting is expected to draw energy ministers from Qatar, Iran, Russia and Venezuela to Santa Cruz, Bolivia.
They gather as gas prices have stabilized over the last year, after plunging more than 80 percent in the prior decade. However, prices remain under pressure due to growing supplies of shale gas and more competition from liquefied natural gas (LNG).
The group is modeled after the Organization of the Petroleum Exporting Countries (OPEC), whose 12 member nations manage oil supply to control prices. "We have to defend our resource, which is gas, and we need to work together so that in the future, gas will be as valuable as oil," Equatorial Guinea's Mines and Energy Minister Gabriel Obiang Lima told reporters as he arrived on Tuesday in Santa Cruz, Bolivia's hub for gas development.
GECF countries increasingly are competing with exports from and prices set in the United States, which is on track to become the world's third largest exporter of LNG after Qatar and Australia.
But GECF Secretary General Seyed Mohammad Hossein Adeli said he saw no global glut of natural gas, pointing to both growing demand and supply.
Global consumption of natural gas grew about 1.5 percent in 2016 to some 3.54 trillion cubic meters (TCM) driven by unconventional gas production, according to BP Plc's statistical review.
Adeli said he expected gas consumption to grow another 2 percent this year, primarily driven by strong demand in Europe and Asia.
At least 25 countries are now capable of receiving LNG supplies and new regasification plants are expected to start operating in the coming months, giving buyers greater flexibility and increasing competition among suppliers.
Even though LNG represents only about 10 percent of the world's gas trade, new suppliers are willing to offer sweeter terms to customers, roiling traditional markets and turning up the heat on some producers trying to hold onto more rigid terms.
That has "buyers in a better position to make contracts with shorter terms and more customized to their demand profile, without risking money in high take-or-pay clauses," said Mauro Chavez, a senior research analyst at consultants Wood Mackenzie.
The United States has been the most aggressive in shaking up the market, through flexible contract terms.
Its rise as a force in global LNG markets and its growing gas sales to Mexico via pipeline have contributed to greater price certainty, according to analysts. This is reflected in a long and flat North American dry gas cost curve that should limit abrupt price increases, they added.
Price indexes are becoming a factor not only in LNG contracts but also in sales via pipeline.
In markets such as the Caribbean, some sellers also are customizing their gas supplies by linking contracts to fuel oil prices, which is also used for power generation. The gas oversupply has fueled some mergers among producers, just as the terms of some of the world's most important gas trade deals are being renegotiated ahead of their expiration dates, including some contracts between Qatar and Japan, South Korea and Taiwan.
Other traditional gas suppliers such as Russia, Norway and Algeria seem determined to maintain market share in key markets such as Europe.
In Latin America and the Caribbean, where U.S. LNG supplies have lowered prices for importers such as Chile and Argentina, traditional suppliers Trinidad and Bolivia need to attract upstream investments, cut costs and offer consumers more pricing flexibility to remain competitive. (Reporting by Marianna Parraga and Alexandra Alper; Editing by Gary McWilliams and Richard Chang)