| Tight sandstone gas as important type of unconventional oil and gas, is today one of the hot oil and gas exploration. For a long time, tight sandstone gas of depression basin has been a focus of research to scholars, the research of tight sandy gas of continental rift basin is weak. Shahezi formation in Xujiaweizi Fault Depression, Songliao Basin is continental rift basins, be of favorable conditions to form dense conglomerate gas, is one of the favorable areas to study tight sandy gravel gas. The knowledge of sedimentology, petroleum geology, sequence stratigraphy is the paper’s theoretical guidance, and the paper integrated use of geological, geophysical, laboratory analysis and other information to research the deposition of times of Shahezi formation, the sedimentary facies, the dense conglomerate reservoir characteristics, the favorable reservoir controlling factors and select favorable experimental area to explore dense conglomerate favorable reservoir prediction and identification technology. Based on the research, the paper selects the favorable zones to propose a well.The paper use the data of regional geology, rock cores,3-D seismic, detection logging to identify the interface between sedimentary, and propose the program that divide Shahezi formation into four. By fine interpretation of three-dimensional seismic data, the stratigraphic distribution characteristics of each segment are determined.By identifying the facies’mark, the study finds that Shahezi formation mainly deposit braided river delta, fan delta, lake such three kinds of sedimentary facies, braided river delta plain, braided river delta front, shallow lake such six kinds of depositional sub facies, and braided channel, sheet sand, overbank such 13 kinds of sheeted sedimentary microfacies. By analysising single well facies and linked well facies, proposes the idea that fan delta develops in the steep slope zone, lacustrine facies develops in depression zone, braided river delta develops in the gentle slope belt. Establish seismic facies recognition template, launch the region’s seismic facies prediction, identified characteristics of sedimentary facies.Establishes Shahezi quarter evolution model based the research of segmentation scheme, sedimentary facies characteristics and feature of tectonic units.By counting more than 90 wells nearly 1200 data, the study suggests that tight sandy gravel is advantage rock of clastic reservoirs in the deep Songliao Basin, it still can form an effective reservoir in the following 3800m. The overall performance of the dense conglomerate reservoir is of low porosity and permeability characteristics, the porosity values mainly in the 2-6% range, and the permeability values mainly in the range of less than 0.1mD.By the use of ordinary sheet, cast sheet rock, mineral analysis testing and other advanced technology, the paper finds that tight sandy gravel reservoir pore types are between gravel pores, dissolution pores, cracks, etc. Diagenesis, tectonic, sedimentary facies and fluid controls the tight sandy gravel favorable reservoir development. The feldspar-rich acidic volcanic gravel porosity is developed; The matte of particles supporting structure is better than hetero supporting structure; Laumontitization is important for feldspar to develop dissolution pores; Rift steep fan delta front and gentle braided river delta front are the main transport zone of acidic fluids, acidic fluid dissolve soluble substances such as laumontitization, expand primary porosity of reservoir, improve the reservoir properties of dense conglomerate.Choosing an experimental area, with the research of wells and seismic, multiple attribute analysis and reservoir inversion, finds that the time of energy half-life attributes (EHT) and colored inversion (SCI) with good response to tight sandy gravel. Based on the research of basic geology and geophysical recognition technology, the paper optimizes Xu Xi, Song Zhan-An Da, Xu Dong three favorable area, and propose Xu Dong 1 well as favorable exploration target. |
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