埋藏成岩作用与塔东北丘里塔格群灰岩段储渗空间的形成

THE BURIAL DIAGENESIS AND THE ORIGIN OF THE PORES/FRACTURES IN THE LIMESTONES OF THE QIULITAGE GROUP,CAMBRIAN-ORDOVICIAN SYSTEMS IN THE NORTHEASTERN TARIM BASIN

塔东北地区系丘里塔格群灰岩段储层中主要储渗空间的形成、演化与多种埋藏成岩作用关系密切。白云石化作用是建立“灰岩段”埋藏成岩序列的关键。大量资料证实,“灰岩段”中明显受合线限制的细晶菱形白云石是埋藏增体积白云石化作用的产物,在5期破裂作用中,只有第3期和第5期裂缝得到保存和改造;而3种类型的缝合线中,也只有Ⅱ型缝合线受到了裂缝的改造,形成了有效微裂缝。

The origins of pores and fractures in the limestones reservoirs of the Qiulitage Group, the Northeastern Tarim Basin are closely related to various burial diagenesis in which the dolomitization is the key process for the limestones. Our recent researches suggest that the aplitic lozenge dolomites limited obviously by stylolites could be produced by burial-volume increasing dolomization. Among the five stages of fracturations, only the third and fifth ones matched the time with the migration of oil/gas in the area. Therefore, the space of pores and fractures could be preserved from the filling up of calcites. In addition, the type Ⅲ stylolites reworked by fracturation can be turned into effective fractures for oil/gas accumulation.