LONDON—Genel Energy PLC, the oil company chaired by former BP PLC Chief Executive Tony Hayward, reported its worst loss since listing its shares more than four years ago in writing down the value of its prized Taq Taq oil field whose reserves have proved lower than expected. The U.K.-listed oil company, once an investor favorite for its promises of growth from a portfolio of oil prospects from Angola to Kurdistan, warned that revenue would fall this year on lower output while it seeks delayed payments from the Kurdish government for oil exports. Genel on Thursday reported a wider net loss of $1.16 billion for the year ended Dec. 31, 2015 compared with a net loss of $314 million the previous year on a 34% drop in revenue to $344 million. The impact of lower oil prices, which plummeted last year, more than offset a 22% rise in Genel’s oil […]