Diagenesis and Thermodynamics Analysis in Clastic Reservoir E13 of North Area of West Qaidam Basin

Key words: 
• diagenesis /
• thermodynamic constitutional diagram /
• calcite /
• dolomite /
• anhydrite

Abstract: Layer E13 in north area of west Qaidam Basin develops good clastic rock. Reservoir properties and diagenesis have a big relevance. To recognize favorable reservoir in E13 in North area of west Qaidam Basin, we divide diagenesis sequence of this area on the basis of core observation, microscope research and analyses experiments, and research the controlling factors of diagenesis further through thermodynamic analyses. In this area, there are four times of widescale diagenesis mainly. The first is dolomite cementation and replacement. The second is calcite cementation and alternation. The third is dissolution and the fourth is anhydrite cementation and alternation. The oil flow happens between dissolution and anhydrite cementation. In addition, compaction and pressolution run through the whole diagenesis. Each diagenesis proceeds in thermodynamic system. Through carefully deduction, we draw five component phase diagram including calcite, dolomite and anhydrite, etc, and get the geochemistry characteristics of diagenesis environment. 