20-Plus Years of Tuscaloosa Drilling: Continuously Optimizing Deep HTHP Wells

Abstract

fax 01-972-952-9435. AbstractDrilling the Tuscaloosa formation in Louisiana was as challenging as any area drillers worked 20 years ago. It was one of the most active areas in the U.S. Problems that were new at the time such as gas solubility in oil base mud, sulfide stress cracking of tubulars, pressure regressions and low margins between the fracture pressure and pore pressures resulted in numerous well control problems and high cost wells. Activity decreased in the mid 80's when the gas price did not encourage operators to challenge the drilling risks. BP Amoco is still successfully drilling to 22,000' into to 16,000 psi, 380°F reservoirs that are now depleted over 10,000 psi. This paper will address steps taken to optimize the drilling operation and continue making the wells economical. First, drilling problems such as stuck pipe, lost returns, drill string failures and well control had to be minimized. Next, successful cement jobs were required and have resulted in the highest rate completions in the history of the Trend. All objectives had to be achieved in a safe manner with little impact on the environment.