巴西坎普斯盆地盐下层系油气发现及其勘探潜力

2002—2012年间,在巴西坎普斯盆地盐下层系接连发现了15个油气田,可采储量7×108t油当量,其中大型油气田11个,凸显了坎普斯盆地的石油潜力,使得该盆地盐下层系成为继桑托斯盆地之后新的勘探热点。坎普斯盆地经历了裂谷期、过渡期和漂移期3个构造演化阶段,盐下层系是裂谷期(侏罗纪晚期—阿普特早期)沉积的典型陆相沉积体系,包括欧特里夫阶裂缝发育的玄武岩基岩和阿普特阶至巴雷姆阶的碳酸盐岩。盆地的主要烃源岩是下白垩统LagoaFeia群黑色钙质页岩,该烃源岩有极好的生烃潜力;盆地发育多套储层。坎普斯盆地盐下层系勘探程度低,目前油气探明率只有约50%,油气潜力巨大。坎普斯盆地盐下层系勘探前景十分广阔,应是未来储量增长最快的领域。勘探的重点地区是中央隆起带;主要油藏类型是LagoaFeia群自生自储型油气藏;主要圈闭类型是碳酸盐岩岩性—构造型圈闭。

Discoveries and Exploration Potential in Presalt Sequences of Campos Basin in Brazil

A total of 15 oil and gas fields were found in the presalt sequences of Campos Basin in Brazil between 2002 and 2012, with the recoverable reserves reaching 7°i108t of oil equivalent. Of those discoveries, there are 11 large-scale oil and gas fields, highlighting the oil potential of Campos Basin and making the presalt sequences of this basin another hot spot for exploration after Santos Basin. Campos Basin experienced three structural development stages - rift period, transition period and drift period. The presalt sequences are the typical continental sedimentary system deposited during the rift period （from Late Jurassic to Early Aptian）, including Hauterivian fracture-developed basement basalt and Aptian to Barremian carbonate rock. The main source rock of the basin is black calcareous shale of Lagoa Feia group in Cretaceous Period, which has an excellent potential for sourcing. A number of reservoirs developed in the basin, where the presalt sequences are low in exploration degree. The current oil and gas proven rate is only about 50 percent, thus indicating a great potential for oil and gas exploration. Campos Basin has a very promising exploration prospect for the presalt sequences, which are supposed to be the field to see the quickest growth in reserves in the future. The focus area for exploration is the central uplift zone. The main reservoirs are Lago Feia group while the main traps are carbonate lithological-structural ones.