Patterson-UTI Energy ( PTEN), the second-largest operator of land-based oil and natural gas drilling rigs in North America, agreed to acquire the shares of TMBR/Sharp Drilling ( TBDI) that it doesn't already own. Patterson-UTI currently holds about 20% of TMBR/Sharp's shares outstanding. Patterson will swap 0.312166 of a share of its common stock and $9.09 cash for each share of TMBR/Sharp. That gives the acquisition a value of $20.20 for each TMBR/Sharp share based on Patterson's Friday closing price of $35.59. TMBR/Sharp is engaged in contract drilling of oil and gas wells in the Permian Basin of west Texas and eastern New Mexico. The company also has exploration, development and production operations in the same areas. The company's stock closed Friday at $19.40, and was recently trading at the $20.20 proposed acquisition price. The 52-week high is $20.30. After completing the transaction, Patterson-UTI will own 358 land-based drilling rigs that operate primarily in oil and natural gas producing regions of Texas, New Mexico, Oklahoma, Utah, Louisiana, Mississippi and western Canada. Patterson was recently adding 71 cents to $36.30.