缅甸D区块超压与油气成藏

Overpressure in Burmese D Block and Reservoir Forming

伊洛瓦底盆地为中新生代发育的弧后—前陆复合盆地,其中D区块具有快速沉积、低地温梯度以及异常超压的特点。探讨了伊洛瓦底盆地D区块异常超压的成因和特征以及和油气成藏的关系。异常超压的成因主要与欠压实作用和构造挤压作用有关。通过D区块4口井的泥岩压实曲线探讨了超压的发育主要以早期欠压实为主,晚期构造挤压为辅的成因机制。最后通过超压对油气藏的封闭保存和对储层的储集性能的改善,以及超压演化对油气成藏分布的影响探讨了超压对油气成藏的控制作用。

Irrawaddy Basin in Burma is a compound back-arc and foreland basin developed from Mesozoic to Cenozoic. D block is just located in this basin and is characterized by fast deposition, low geothermal gradient, and abnormal overpressure. In this paper, the origin and features of abnormal overpressure and its relation to reservoir forming are discussed. The origin is mainly relative to undercompaction and tectonic compression. Moreover, from compaction curves of mudstone for four wells in the block, it is found that the origin mechanisms are based on early undercompaction and aided by later tectonic compression. At last, the effect of overpressure on reservoir forming is explored in terms of three aspects, including overpressure preserving reservoir, overpressure improving reservoir property, and overpressure evolution affecting reservoir- forming distribution.