QatarEnergy is expected to announce a major long-term supply agreement with the biggest power utility in Japan, allowing the world’s second-largest LNG exporter to regain some of the market share it has lost there over the past decade. As soon as this week, QatarEnergy is set to announce a supply deal with Jera Co, Inc, the largest power generation company in the G-7 Asian economy, anonymous sources familiar with the negotiations told Bloomberg on Tuesday.      The agreement would be for QatarEnergy to supply about 3 million…