Health Safety & Environment:
Zero-Discharge Rigs

The industry has applied its considerable ingenuity and determination to protect the environment so that oil and gas wells can be safely constructed offshore. An example of this effort is the development of the Mobile Bay area, offshore Alabama. Zero-discharge means exactly what it says—nothing will be allowed to fall into the sea after it has touched the rig. This includes indigenous rainwater. Also included in the rules are 3 categories of solid discharge—industrial waste, sanitary waste and wellbore cuttings—and 7 categories of liquid discharge. Besides weather runoff, these include cooling water, sanitary water, waste oil, drilling fluids, and machinery deck and mud processing drainage. 

Meeting these exacting requirements were rigs contracted by the developer, ExxonMobil. These included the Rowan 4, Penrod 65 (now Noble Bill Jennings), GlobalSantaFe High Island IV, Penrod Portal 202 (now Noble Joe Alford), Chiles Seabee (now Noble Tom Jobe) and the Penrod Prober 94 (now Ensco 94).  It should be noted that in addition to operating under zero-discharge rules, the rigs had to contend with dangerous hydrogen-sulfide gas, necessitating stringent safety regulations for personnel and equipment. 

The State of Alabama should be justifiably proud of its role in developing the zero-discharge regulations, and the success it has achieved in safely producing hydrocarbons from beneath Mobile Bay. ExxonMobil is to be commended for its role in proving that the petroleum industry can safely drill and produce offshore while protecting the environment. 

Recognizing the pioneering efforts of the following individuals and companies who contributed to the development of this technology: 

The State of Alabama, Chiles Drilling (now Noble Corporation), ExxonMobil, Global Marine (now GlobalSantaFe), Penrod, Rowan Companies, Transworld Drilling (now Noble Corporation)