OREANDA-NEWS. Colombia's state-controlled Ecopetrol reported an 11pc decline in proven crude, condensate and natural gas reserves to 1.849bn bl of oil equivalent (boe) at the end of 2015, down from 2.084bn boe a year earlier.

The decline cut Ecopetrol's reserves-to-production ratio to 7.4 years, down from 8.6 years in 2014.

"The reduction in proved reserves was mainly driven by the plunge of hydrocarbon prices," Ecopetrol said.

The reserves data also reinforces a declining trend that reflects a lack of significant discoveries in recent years.

A negative effect of 404mn boe from low oil prices was offset by additions of 275mn bl tied to "cost optimizations and higher efficiencies," 67mn bl from drilling at key fields Castilla and Rubiales, and from "positive revisions of some fields such as Chichimene," Ecopetrol said.

Another 47mn boe positive effect was attributed to the inclusion of gas self-consumption on proved reserves.

"The highest contributions to the reserve balance were from the Castilla and Chichimene fields, both directly operated by Ecopetrol, and from the Rubiales field, which will be operated by Ecopetrol as of July 2016," the company said.

Unless the company reduces production this year, it could post another downward revision of reserves-to-production at the end of 2016, a local financial analyst says.

The company has already suspended some production this year because of the low oil price scenario.

Ecopetrol said today it received authorization from Colombia's oil regulator ANH to temporarily suspend the Akac?as oil field on block CPO-9 in Meta province, following the suspension of the Ca?o Sur field on 18 February.

Ecopetrol operates 6,699 b/d Akac?as with Spanish partner Repsol, which holds a 45pc stake.

ANH told Argus that it is reviewing requests from various operators to temporarily suspend production because of sustained low oil prices.

The lack of significant onshore discoveries in recent years is spurring Ecopetrol and other companies operating in Colombia, including US independent Anadarko, Shell, ExxonMobil and Repsol, to explore offshore Caribbean areas.

Of total reserves, 99pc were audited by Ryder Scott and DeGolyer and MacNaughton, Ecopetrol said.

Ecopetrol S.A. contributed 95pc of proved reserves, with subsidiaries Hocol, Ecopetrol America, and interest in Equion and Savia Peru contributing the balance.