Research About The Reservoir Characteristics Of The Cambrian Dolomite In TS1 Well, And Its Geochemical Characteristics

The carbonate formation plays an extremely important role in the whole world's oil and gas production. And almost 50% of the carbonate reservoir is dolomite, which has been fully proved by the petroleum exploration practice of the paleozoic carbonate in the Tarim Basin.TS1 well is the frist super-deep scientific exploration well in the world, which aim is for finding oil and gas. On the condition that the depth is more than 8000m, temperature is more than 170℃, and pressure is more than 80 Mpa, the development of its reservoir space is very good, such as solution pore and cavity, fracture. It has revealed good dolomite reservoir, and has showed the broad propects of deep oil and gas exploration in Tahe region. So it has significant theoretical and practical value to do research about the reservoir characteristics and geochemical characteristics of the Cambrian dolomite in TS1 well.In this study, the core datas of Ts1 well become particularly important, for Ts1 well is the only super-deep well drilled to the Cambrian, in northern tarim basin, its mechanism of the reservoir development is comparatively complicated, and there is no well to analogy. So the research about the lithology, and the diagenesis of Ts1 well, through cores observation, the rock thin-section identification and so on, becomes particularly necessary and important. Then, we do some tests and anlysis of the samples, through the Geochemical Analysis, such as C,O,Sr isotope, and fluid inclusion analysis, Combined with the lithology, we analyze and discuss about the Cambrian dolomite genesis of Ts1 well. Through physical properties, log data, we analysis and research the reservoir quality, then, we make the analysis and discussion about the control factors of the reservoir development.Summary from research, the rock types of the Cambrian dolomite in TS1 well include Micrite and Micro crystallized dolomite, Algal laminated dolomite, Grained dolomite, and Crystallized dolomite, and the main type is Crystallized dolomite. Digenesis include compaction, dolomitization, silicification and dissolution etc. And the dolomitization and dissolution are the main factors. There are four types of dolomite genesis, penecontemporaneous dolomite, the mixed water genetic dolomite, deep-buried genetic dolomite, and hydrothermal genetic dolomite. The type of reservoir space mainly is fracture and solution pore. The upper is mainly fracture, the pore size is very small, and almost is the acicular-dissolved holes. And downwards is mailnly about the solution pores, the pore size increases gradually. While, the fracture is reduced gradually. The reservoir physical parameters gradually become better with depth. But although the porosity of the reservoir is better, the permeability is not good enough, so the connectivity is poor, and the total physical properties is poor relatively.The fracture which formed by the Caledonian period structure activity have showed the important role to the deep cambrian reservoir. The deep fracture can be the channel of underground fluids, or can provide the space for the dissolution process. Meantime the dolomitization is the main diagenesis, the dissolution related with the deep fracture hydrothermal fluid improved the reservoir quality of the cambrian dolomite reservoir. But it is proven by actual drilling that there is not effective sealing condition, which is the main geological factor restricted the reservoir forming of Ts1 well district.