The Application And Evaluation For The Reservoir In The Penglaizhen Formation Of Upper Jurassic At The Luodai Gasfield, The Sichuan Basin

In order to increase natural gas reserve at the Luodai Gasfield, theSichuan Basin, this thesis studies the sedimentary facies and the geophysicalmodel for the reservoir in the Penglaizhen Formation of Upper Jurassic atthe Luodai Gasfield, by application of neural network technique. And theauthor makes a gas reservoir evaluation and proposal for the Gasfield.Investigations show that the Luodai anticline is a secondary structure ofthe NE fault on the eastern flank of Longquanshan maintain. The anticlinewas formed by not only regional compression but also differentlithologies(sandstones at the anticline axis, mudstone on the flanks). Thereare two highs on the Luodai anticline. Sandstone reservoir of thePenglaizhen Formation at Luodai Gasfield represents sediments ofmeandering river, braided river and abounded channel. The author made aseries thickness contours and sedimentary facies maps for the sandbodies of18 sand layers in the Penglaizhen Formation.Geophysical model of gas reservoir reveals the gas-bearing sandbodiesat the Luodai Gasfield. The sandbodies appear obviously in low velocity.The porosity, permeability and gas maturity of the sandstones are in linearrelations with the velocity. Gas-bearing sandstones are of characteristics oflow velocity, strong amplitude, low frequency, low associated dimensionand low trace integration. Using neural network, oil & gas distribution waspredicted comprehensively on geological, seismic and logging data. Thepredictions was proved correct with drilling and logging data.In accordance with the comprehensive evaluation, sandbodyJP₄³(layer-18) was the main production sandstones. The author postulated7 production wells. This is the first application of comprehensive geologicaland seismic interpretation for the gas sandbodies in the Sichuan Basin,which is of theoretical and practical significance in gas exploration and production in the basin.