Study On Oil-bearing Formation Above Chang-2’s Reservoir-forming Rule And Favorable Area Prediction In Hujianshan Region

Based on the theory and methods of sedimentology, lithofacies-paleogeography,petroleum geology, petrology, geophysical well logging, seismology, taking oil-bearingformation above Chang2as research object, the structure, sedimentary facies, reservoircharacteristics and reservoir characteristic of its sand layer and oil-bearing sand bed werestudied. The Chang2layer of Triassic, Yan9layer and Yan10layer of Jurassic were keyresearch target. The field core observation, analysis of lithology profile, logging curve,seismic section and drilling cores data, and indoor test were combined in the study. Afterstudying the distribution properties of oil-pool, it was thought that the pool was characterizedby widely distribution, rich reserves and effective development, and it would be the mainexplorating direction for increasing storage.When the comparison and division of fine formation were done in more than300wells,the key section was built, then multi-wells section analysis had been done, and sedimentarymicro-facies and characteristic of sand-body distribution were conferred. The reservoirs ofChang2and Yan9were considered as meandered river delta plain sedimentary, and Yan10was meandered river sedimentary. The general sand-body spreading direction of Chang2wasNNE-NNW, Yan9and Yan10’s sand-body were mainly developed in ancient valley regions,and their direction were mainly controlled by sedimentary facies zone. After evaluationstudying reservoir’s characteristics of petrology, pore structure, diagenesis, substance andheterogeneity, it was found that Chang2reservoir’s main constituent was feldspar, Yan9andYan10were debris-feldspar. The reservoir’s was maturity relatively low, sorting featuresbeing between medium and good, the combination type of hole and larynx being intergranular-feldspar pores, psephicity semi-edge-angle, texture maturity medium,hole-larynx sorting features medium, and heterogeneity relatively low.In this paper, the pool-forming types of the studying area was detailed analyzed, whenthe reservoir’s controlling factors were studied from aspects of sedimentary facies, structure,cap rock, carrier bed, and so on. Then, pool-forming model was built, and favorable area waspredicted. This paper will guide the following exploration and development in Hujianshanarea.