Researeh On Evolution Of The Tight Reservoir In The Southwestern Sulige Gas Field

In order to understand the evolution of the tight reservoir of He8and Shan1member ofUpper Paleozoic Permian, this paper comprehensive analyzed the laboratory data of castingthin sections, cores, inclusion of He8and Shan1members by using scanning electronmicroscope, electron probe，X ray difrfaction and other advanced test instruments and means.The result shows that the evolution of the tight reservoir corresponds to the diagenetic verywell. It can be divided into three stages. This paper may not only enrich the theoreticalknowledge of tight sandstone reservoir, but also play a guide role to the exploration anddevelopment of objective layer. This paper carired out detailed and deep analysis on thesediment structure, diagenesis, sedimentary burning history and organic mateiral evolvementof Upper Palaeozoic Permian He8and Shan1member in the southwestern Sulige gas ifeld.There are three evolution stages of the tight reservoir: First, the reservoirduirng early diagenesis from Permian to Early-Middle Tirassic. The prosity of the quartzsandstone reservoir is about34%. After the early diagenesis, the porosity is about17.5%,Second, the reservoir entered the late diagenesis Ai period in the late Tirassic, the porosity ofsandstone reduced to about17%, because the buired depth of strata increased further. But thedensiifcation of the reservoir in this peirod is weaker than in the early diagenetic peirod for thedissolution of unstable component. Third, the evolution of reservoir entered the late diagenesisA2peirod in the Middle Jurassic, The porosity is about7.8%in this peirod, about7%now, andthe permeability is generally less than1x10^-3/μm², the sandstone reservoir can be called fortight sandstone reservoir in the peirod. The main factor of densification is the cementationduirng the late diagenetic peirod. The secondary pores formed by the corrosion, intergranularpore and micro-fractured are beneficial to improve the tight reservoir.