Pemex employs about 140,000 workers, most of which are members of the union.
The new head of PMI Comercio Internacional Isaac Volin Bolok will start the post on June 27.
Pemex, which has suffered from a prolonged oil rout, will sell some of its infrastructure assets to the fund, but will continue to operate and maintain them for 15 years and pay rent to KKR.
Gulf Mexico plans to open 100 gas stations this year in Mexico's 18 biggest cities, and ramp up to about 17 percent of the national market in three years.
President Enrique Peña Nieto traveled to the site of the blast accompanied by federal authorities.
Due to a prolonged rout in global oil prices, Pemex said last month it would put billions of dollars worth of projects on hold, including those focused on exploration.
The company, which operates six domestic refineries, will refine 1.134 million barrels per day (bpd) this year, compared with 1.066 million bpd in 2015.
Pemex data showed average exports rose to 1.12 million barrels per day (bpd) from 1.008 million bpd in December.
The auction makes the third phase of the so-called Round One tender.
Pemex has entered into a partnership with Global Water Development Partners (GWDP) that aims to invest US$800 million in water treatment infrastructure projects.