Seismic Acquisition Technique For Volcanic Reservoir In The Northern Margin Of Junggar Basin

The Ulungu area in the northern margin of the Junggar Basin spans two first-order tectonic units:the Ulungu depression and the Luliang uplift,including three secondary structural units:the red rock fault zone,the Suosolquan depression and the quartz beach bulge.For the Upper Paleozoic including the Carboniferous system,it mainly consists of a set of marine-continental transitional clastic rocks and volcanic rocks.According to the existing geological data,a set of north-west distribution of the Lower Carboniferous normal sedimentary strata is developed under the high-resistance volcanic rock.The Carboniferous volcanic reservoirs and argillaceous source rocks of the Ulungu depression and the Quartztan beach bulge are developed.Many wells show good oil and gas and have great exploration potential.The type of gas reservoirs in this area is mainly layered and block-shaped.The gas reservoirs are mainly controlled by volcanic lithology.The gas layers are thick and large in scale.The reservoir lithology includes basalt,andesite and rhyolite.For the volcanic rock development area,the seismic wave velocity and density of the volcanic rock region are greatly different from surrounding rock,which makes the seismic wave energy spread downward difficultly.Layer under the volcanic rock produces weak reflection or blank area which brings the obstacle on seismic exploration for the volcanic rock region.In order to improve the exploration effect,the optimal observation system and excitation parameters,which increase downward energy,are selected;The combination mode of the detector is optimized,which improve the ability to receive deep weak reflection signals.