松辽盆地长岭断陷火山岩储层识别与勘探目标评价

Changling fault depression is the biggest fault subsidence in south of Songliao Basin. In its Lower Cretaceous Yingcheng and Shahezi formations developed thick source rocks of deep lake facies and developed poly-phase volcanic rock reservoirs as well. In recent years, significant breakthroughs have been obtained in hydrocarbon exploration of volcanic rock reservoir in the different fault depressions in Songliao basin. Lately, I have been involved in hydrocarbon exploration in the Changling rift depression, especially volcanic rock reservoirs and exploration targets research, participating in the deployment of well Yaoshen 1 which gained over 40 × 104m3 natural gas flow. As quick changes of lithology and facies in Changling area in the south of Songliao basin, and the volcanic rock interludes distribution in continental clastic rock and shale in 3D space, so the identification of volcanic rock types and distribution become a difficult problem. Thus, based on the integrated research of the wild outcrop observation, gravity, magnetic and seismic data, geophysical logging, drilling and coring, laboratory test, this paper carried out the reservoir identification, description and prediction of volcanic rocks in Changling fault depression. In this area, this paper analyzed the volcanic rocks litho-facies, the eruption period, and characteristics of cycles. At the same time, tried to know how to use logging, seismic data to separate volcanic rocks from sandstone and shale, distinguish between volcanic reservoir and non-reservoir, distinguish between intermediate-basic and acidic volcanic rocks, and how to identify traps of volcanic rocks and its gas-bearing properties, etc. Also it is summarized forming conditions and distribution of traps, and possible gas-bearing traps were optimized queuing management. Conclusions as follows: There are two faulted basements in Changling fault depression, granite basement in the southeast and upper paleozoic epimetamorphic basement in the northwest. The main volcanic reservoirs developed in Yingcheng period, which was the intermediate-basic and acidic volcanic eruptions, from the south to north by the intermediate-basic to acid conversion. The volcanic vents are gradually young from south to north. According to information of the re-processing 3D seismic data and gravity-magnetic data, the large volcanic vent or conduit was mainly beaded-distributed along the main fault. The volcanic rocks thickness in Yingcheng formation was changed by the deep faults and basement boundary line. Compared with the clastic rocks, volcanic rocks in Changling area are with high resistance and velocity (4900-5800), abnormal Gamma. All kinds of volcanic rocks are with abnormal strong amplitude reflection on the seismic stacked section except tuff. By analyzing the seismic facies characteristics of volcanic rocks, optimizing seismic attributes constrained by logging, using seismic amplitude and waveforms and other attributes divided volcanic rocks of Yingcheng formation into four seismic zones in map. Currently, most volcanic gas reservoirs are fault-anticline and fault-nose structure. But the volcanic dome lithologic gas reservoirs with large quantity and size are the main gas reservoir types to be found.