Halliburton Co (HAL.N) filled a gap in its offering of oil and gas extraction services with a deal to buy Multi-Chem Group LLC, North America's fourth-largest production chemicals company.

Halliburton, the world No. 2 in oilfield services, sees increasing demand among all its customers, including the leading integrated oil companies, for more services under one roof, Chief Executive David Lesar said.

It has been frustrating pumping competitors' chemicals with our equipment, he told investors at the Barclays Capital 2011 CEO Energy-Power Conference in New York on Tuesday.

The acquisition of San Angelo, Texas-based Multi-Chem, announced earlier on Tuesday, was for an undisclosed price. It is expected to receive regulatory clearances in the fourth quarter, Halliburton said in a statement.

According to a business group promoting the area around San Angelo, Multi-Chem has 650 employees, 750 customers worldwide, and operates in North America, Western Europe, Indonesia and Argentina. A Multi-Chem spokeswoman was not available for comment.

Halliburton shares fell 3 percent on the New York Stock Exchange, while the Philadelphia Stock Exchange oil service index .OSX was down 2 percent, in line with oil prices.

Chief Financial Officer Mark McCollum told the conference that Halliburton's outlook had not changed, with North America set to grow more as clients base their plans on oil prices substantially below current prices, while the improvement in international markets remained slow and steady.