Patterson-UTI Energy ( PTEN), a contract oil and natural gas driller, said earnings rose sharply in the fourth quarter compared with a year ago. The company earned $134.2 million, or 77 cents a share, in the quarter, compared with $34.2 million, or 20 cents a share, a year ago. Adjusted for items, earnings were 80 cents a share in the most recent quarter, surpassing the expectations of analysts surveyed by Thomson First Call by 7 cents. Fourth-quarter revenue rose 84% from a year ago to $531.2 million, topping analysts expectations of $510.4 million. "The record results for the fourth quarter and the full year of 2005 reflect strong performances from all of our operating segments, including our pressure pumping operations, drilling and completion fluids segment, and oil and natural gas exploration activities," the company said Thursday. Revenue from contract drilling rose 94.9% to $459.8 million. During the fourth quarter, Patterson-UTI had an average of 292 rigs operating, up from 283 in the third quarter. The company estimates its rig count will increase to 300 in the first quarter. The company also said its board approved an increase in its stock buyback program, authorizing future purchases of up to $200 million of its common shares. Shares of Patterson-UTI were rising $2.10, or 6.9%, to $32.45.