Houston-based oil-services provider Allis-Chalmers Energy Inc. (NYSE: ALY) has acquired Diamondback Oilfield Services Inc., Conroe, Texas, for $22 million. Assets include personnel and equipment, including approximately 18 directional drillers, 30 downhole motors, five measurement-while-drilling tools and eight wireline-steering vehicles. During 2006, Diamondback generated approximately $15 million in revenues. This expands Allis-Chalmers' directional drilling segment deeper into the Texas Panhandle and Oklahoma.