Nabors Industries Limited is an American global oil and gas drilling contractor that has operated since 1972. Based in Houston, Texas, Nabors operates the world’s largest land drilling rig fleet, with around 500 rigs operating in over 25 countries – in almost every significant O&G basin on the planet. It also has the largest number of high-specification rigs and custom rigs, built to withstand challenging conditions such as extreme cold, desert and many complex shale plays. Wikipedia