Houston-based Patterson-UTI Energy Inc. has set April 20 as the date for shareholders to vote on its nearly $2 billion acquisition of Oklahoma City-based Seventy Seven Energy Inc., according to a release. Shareholders of record at the close of business Feb. 22 will receive notice and can vote at the special meeting, per the release. Patterson-UTI (Nasdaq: PTEN) announced plans in December to buy Seventy Seven (OTCPK: SVNT) in an all-stock deal valued around $1.76 billion including debt. The deal...