Reef Reservoir Prediction In WBT Structure In Northeast Of Sichuan

Marine carbonate regions in south of China are important areas for oil and gas exploration. In recent years,with further oil and gas exploration work,It find industrial gas in reef reservoir in upper Permian system Changxing group and lower Triassic Jialingjiang group in Longgang and Tongnanba area . The main layer of Puguang field was Feixianguan group,All of those great discoveries and break point out that there are big exploration and development potential in the reef reservoir of upper Permian system Changxing group and lower Triassic Jialingjiang group, have a nice oil-gas exploration prospect. The study area of this paper–WBT exploration area is located in the eastern part of Tongnanba exploration area in Northeast of Sichuan, and oolitic reservoir develops in this area. But it is difficult to carry out more accurate predictions for this kind of reservoir by a single type of geophysical methods because that the oil and gas exploration level in WBT area is less and the study of sedimentary facies and reservoir is not in depth enough,but also carbonate reservoir itself has a strong heterogeneity.This paper taking the oolitic reservoir of the upper Permian system Changxing group in WBT area as the main study object,based on full collections and analyses of the geological,seismic,drilling,logging and testing well data in the work area, made horizon calibration and contrast for intended formation,and using neural network seismic waveform classification technology,seismic attribute analysis techniques, impedance inversion technology and the absorption attenuation analysis technology, forecasted the distribution of reef reservoir,at the same time,probed favorable oil and gas areas of reef reservoir,and ultimately proposed seismic prediction process suitable for reef reservoir. First of all,for the seismic response characteristics of the reef reservoir–middle-low frequency,non-cluttered and middle-weak continuity and weak reflection,use the forward modeling,attribute analysis,waveform classification methods to obtain the seismic facies division and find possible reef development region. Then,in the predicted reef reservoir development areas use wave impedance inversion and absorption attenuation analysis technology to analyze the reef reservoir fluid, further enable the distribution of reef reservoir area. Finally,integrate geological,drilling,seismic and other information,to reservoir prediction in the study area.By the above analysis,this article has made the following major achievements and understanding:(1)analyzes and summarizes the seismic characteristics (weak reflection, there are is continuous strong amplitude below it ,the frequency turn low at lateral the distribution area )and of the top of upper Permian system Changxing group, it is benefit to find the reef reservoir.(2)To the reef reservoir special development facies(platform edge shallow facies or platform facies) he waveform classification based on self-organizing neural network can better achieve the division of reef reservoir seismic facies, and find a new extend longer platform edge shallow facies branch, it predict that there are develop two benefit stripe of Changxing group reef reservoir. preliminary form the seismic prediction technology which is for reef reservoir of the area, further confirmed and refining the distribute platform edge shallow facies and the reef reservoir distribute.(3)Predicting the thickness, porosity ,storage factor and the distribute of the Changxing group reef reservoir, and dividing the gas accumulation zone. in conclusion, taking advantage of the technology mention above can better predict the reef distribute rang and the spatial form and the reservoir benefit area, offer the proof for the well drill deploy.