ON THE SANDSTONE COMPACTION OF JURA-TRIAS SYSTEMS AND THE PETROLEUM GEOLOGICAL SIGNIFICANCE IN THE NORTHEAST TARIM BASIN

The sandstone compaction of Jura-Trias systems is both widespread and severe in the Northeast Tarim Basin, of which the mechanical compaction predominates the chemical one. The mechanical compaction is generally strengthened along with increasing of burial depth, but not always transformed into chemical compaction. However, the sandstone compaction is mainly dominated by rock property, sedimentary environment and burial history. In accordance with compaction strength, the sandstone compactions in the study area can be divided into three grades of Ⅰ, Ⅱ and Ⅲ respectively. The more severe compaction, the more favourable for oil/gas generation, but unfavourable for the formation and the preservation of pores. Therefore, the weak compaction is favourable for the development of good reservoirs, but disadvantageous to the transformation of organic matter.