• NiSource Inc., Merrillville, Ind., is selling Columbia Energy Resources Inc., including Columbia Resources Canada Inc. and its gas exploration and production business. Columbia Resources has interest in more than 8,000 wells in the eastern U.S., while Columbia Resources has holdings in New Brunswick and Ontario. Columbia is estimated to have reserves of 1.1 trillion cu. ft. of gas. Credit Suisse First Boston is advising NiSource on the divestment. • Unocal Corp., El Segundo, Calif., will acquire Pure Resources Inc., Midland, Texas, for 0.74 share per Pure share. Unocal's 0.70-share offer was rejected. Pure's second-quarter production was 380 million cu. ft. of gas equivalent per day. • CMS Energy Corp., Dearborn, Mich., has sold the remaining assets of CMS Oil and Gas Co. and its affiliate CMS Oil and Gas (International) for $167 million. • Westport Resources Corp., Denver, has acquired southeast Texas oil and gas properties from Smith Production Inc., Houston, for $120 million. The properties produce approximately 29 million cu. ft. of gas equivalent, net, and have total proved reserves estimated at approximately 76 billion cu. ft. of gas equivalent, 82% gas. The assets also include 10,000 net undeveloped acres and an interest in 300 square miles of 3-D seismic data. • St. Mary Land & Exploration Co. unit Nance Petroleum Corp. plans to acquire properties in the Williston Basin of Montana and North Dakota from Burlington Resources Oil & Gas Co. LP for $76 million in cash. The properties produce an estimated 3,100 bbl. of oil and 3.3 million cu. ft. of gas and contain an estimated 61 billion cu. ft. of gas equivalent of proved reserves, 97% developed. • Samson Investment Co., Tulsa, Okla., has acquired gas properties in Sweetwater County, Wyo., for $40 million from EnerVest Energy LP and EnerVest Operating LLC. The properties contain numerous behind-pipe and drilling locations on approximately 55,535 acres of leasehold. • The Houston Exploration Co. has acquired additional working interests in eight offshore producing blocks in the central and western Gulf of Mexico from KeySpan Energy Exploration & Production LLC, a subsidiary of KeySpan Corp., for $26.5 million in cash. Estimated acquired proved and probable reserves are 18.6 billion cu. ft. of gas equivalent and production is approximately 15 million cu. ft. of gas equivalent per day. The assets also include Keyspan's offshore lease holdings of 11,100 net acres. • Ward Petroleum Corp., Enid, Okla., and Output Exploration LLC, Stafford, Texas, have acquired 80 properties in the Golden Trend in Garvin and McClain counties, Okla., from ExxonMobil. The properties are predominantly gas-producing from multiple formations including the Hart, Hunton, Sycamore, Viola and Simpson. • Carbon Energy Corp., Denver, has sold its interest in 20 producing wells primarily in Stanton and Morton counties, Kan., for $2.3 million. The company plans to focus on the development of its gas properties in the Piceance and Uintah basins in the Rockies and in central Alberta and exit the Permian Basin region. • GMX Resources Inc., Oklahoma City, has sold most of its Kansas properties to two Wichita, Kan.-based companies for $3.6 million. The assets comprised approximately 10% of the company's total proved reserves. Proceeds were used to pay debt. The average purchase price for both transactions per thousand cu. ft. of gas equivalent was approximately $0.53, according to GMX. • Invader Exploration Inc., Calgary, plans to acquire Teal Energy Inc., which holds interests in six properties in Texas and six in Canada with total daily production of 87 BOE. • Rocky Mountain Energy Corp., Houston, has acquired U.S. Oil Co., Denver, for $2.9 million. U.S. Oil owns interests in the Ten Mile/Desert Springs Field in Sweetwater County, Wyo., consisting of more than 8,000 acres. • Upton Resources, Calgary, plans to sell its U.S. producing assets to an undisclosed party. Upton produces about 700 bbl. of oil a day.