Early-Stage Description Technique And Its Application Of Fluvial Facies Sandstone Gas Reservoir

In the light of universal distribution of the fluvial facies gas reservoir sandbody in china , the authors bring forward a reservoir description technique which is suitable to the fluvial facies gas reservoir and apply it to the He8 gas reservoir in SuLiGe gas field by taken sandstone distribution as a center through a series researches of stratigraphic division, sedimentary system, high resolution sequence stratigraphy, seismic sandbody recognition, analyzing the data of horizontal well and modified isochronous testing, reservoir physical property and diagenesis,early-stage reservoir comprehensive evaluation, 3D visualization of sandstone etc.The sedimentary system and sandbody distribution of He8 gas reservoir are analyzed. It is fully embodied by the mutual verification of multi-methods and multi-discipline integrated application of geology, logging, seismic, testing data etc. Geological statistics and fuzzy prior decision technique are widely used to establish the geology model of sandbody distribution of the fluvial reservoirs.Some results and innovation of the paper as fellows:Firstly, the sedimentary facies and sedimentary environment of complex sandstone reservoir are confirmed by synthesizing multi- discipline such as analyzing field sections and cores, seismic inversion , high-resolution sequence stratigraphy, well logging facies identification, rock lab analysis etc. Using the above methods, it is confirmed that the He8 gas pool is fluvial-alluvial plain sedimentary system instead of delta sedimentary system which was previously regarded. The new facies model is an important guidance to the exploitation of the gas pool.Secondly, In the light of strongly dispersed distribution of the fluvial facies gas reservoir sandstone, the authors succeed in identifying the sandstone distribution rule and firstly identifying the single sandstone distribution model of He8 gas reservoir and providing the geologic basis for arranging well pattern to the exploitation of gas reservoir by using 2D seismic fuzzy recognition technique, field fluvial beach observation, 3D visualization and drilling horizontal well technique.Thirdly, the size of single sandbody is studied by introduction of two sophisticated gas pool engineering techniques 梔rilling horizontal well and modified isochronous testing. By analyzing about 1000m horizontal sections log data of well SuPingl and well SuPing2, modified isochronous testing of well Su4, Su5, Su6, SulO, and observation of the field sections, the width and range of single sandbody and complex sandbodys are ascertain.Fourthly, in order to display the complex distribution of fluvial sandbody vividly, the authors carry through the 3D visualization description technique based on the 2D seismic data. By using the technique, the established geologic model would be more intuitionistic, more solidand more easily to select the favorable parts of gas reservoir.Fifthly, using advanced technology, such as identifying core slices, temperature measurement of inclosure, oxygen isotopes detection of autogenic quartz, electron probe detection of calcite cement and so on, the quantitative model of porosity evolution, diagenesis pattern and facies are established to offer a reference for finding secondary develop zone in the area.In a word, the early-stage reservoir description technique which is suitable to the fluvial facies gas reservoir is of great importance to the exploitation of gas pool onshore and the western gas to east transmission project.