Mexico’s oil industry regulator CNH (Comisio Nacional de Hidrocarburos) on Friday announced a few more changes to the bidding rules to determine the partner for state oil firm Pemex in next month’s auction for deep-water oil-drilling rights, according to Reuters.

It will be the country’s first deep-water project and will mark a major step in the energy reform process started in 2013, a process that essentially breaks down Pemex’s monopoly in a bid to improve efficiency and output.

The field at stake is called the Trion block located in the Perdido Fold Belt near the maritime border with the US. It is believed to contain around $480m barrels of oil equivalent worth about $11bn.

The new rules changes announced by CNH include: removing Pemex’s right to unilaterally remove whichever company is chosen as its joint venture partner; and removing a cash bond that was included in the joint operating agreement.

Last month CNH had made another significant change that allowed a single company alone to bid to become Pemex’s JV partner, where previous rules had required a minimum of two firms in a consortium.

And prior to that CNH had reduced Pemex’s minimum stake in the project from 45% to 40%.

The licence contract will be awarded on December 5.