Diagenesis of Sandstone Reservoirs in Jingbian Gas Field, Ordos Basin

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Science & Technology Review ›› 2010, Vol. 28 ›› Issue (21) : 37-42.

Articles

Diagenesis of Sandstone Reservoirs in Jingbian Gas Field, Ordos Basin

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Abstract

The low porosity and low permeablity of Permian sandstone reservoirs are the key puzzling issues in gas exploitation in Jingbian gas field, Ordos basin. To analyze the poor property of sandstone reservoirs and improve the accuracy of reservoir forecast, the diagenesis and its controls on reservoir property of sandstone in this area are studied by using systematic slice identification, mercury penetration，cathodoluminescence and scanning electron microscope. It is shown that lithology of P2h8 sandstone in Jingbian gas field is dominated by lithic sandstone, lithic silicarenite and silicarenite with carbonate, gaolinite, chlorite and siliceous cementation. Content of carbonate cementation influences greatly the properties of reservoirs. Reservoir space is domanited by secondary porosity, including the remaining primary intergranular pores, intergranular dissolution pores, intergranular corrosion expanding pores, intragranular dissolved pores, intergranular pores in Kaolinite, and some micro-cracks. Sandstone reservoirs in P2h8 consist mainly of rocks of type II and type III with small portion of rocks of type I. The sedimentary microfacies and the diagenesis controlled development of reseroirs are considered as the main material basis of reservoirs. Well diagenesis alteration is the key factor that determines properties of reservoirs. Compaction and cementation are the main controls on degrading physical properties of reservoirs. Extensively developed dissolvement of aluminosilicate minerals plays a key role in improving properties of reservoirs.