El Paso Natural Gas to Buy Tenneco Energy for $4 Billion: The sale of Houston-based Tenneco Energy Co. will further the evolution of Tenneco Inc. from a conglomerate with roots in the natural gas business to a leading auto parts and packaging supplier. Tenneco Energy has 18,710 miles of pipeline, the company said. Its assets include major interstate gas pipelines and gas pipeline projects in Australia, South America and Asia. The interstate pipelines include the Tennessee Gas Pipeline, which transports gas from the Gulf of Mexico to the Northeast. El Paso Natural Gas Co.'s pipeline network stretches from west Texas to California. By acquiring Tenneco’s energy assets, El Paso will have a pipeline system reaching from coast to coast.