STUDY ON DIAGENESIS OF THE MIDDLE AND UPPER JURASSIC RESERVOIR IN TURPAN DEPRESSION

The main diagenesis of the middle and upper Jurassic reservoirs in Turpan Depression is studied by means of the casting thin sections, scanning electron microscope, X-ray diffraction and physical properties. Compaction and cementation are the major factors turning the pore texture of reservoir worse; while dissolution is the major factor making the pore texture of reservoir better. Dissolution transformed the physical properties of reservoirs. Modified by dissolution, the clastic rock of Sanjianfang-Xishanyao Formation in the middle Jurassic became the most important reservoir of oil and gas with its high porosity and permeability in Turpan Depression.