Potential Evaluation Of Oil-gas Reservoir Based On New Optical Methods

With the development of economic soial and energy industrial,traditional oil and gas resources are becoming increasingly missing.On one hand,the potential evaluation is necessary for the petroleum that has been found,thus scientific measures will be taken to exploit the oil-gas.On the other hand,the potential evaluation is also necessary for the unknown block so that the correct theory will be used to guide exploration practice.Consequently,both practical and economic methods should be developed by the researchers to enrich the theoretical system of oil-gas exploration.Optical techniques have the characteristics of non-contact,low-cost and insensitivity to the geomagnetic and geoelectric fields.In this report,new optical methods including terahertz(THz)spectroscopy and oblique-incidence reflectivity difference(OIRD),which are rapidly developed in recent years,are employed to evaluate the oil-gas reservoir especially the unconventional reservoirs.Meanwhile,spectrum analysis methods are also developed for the sake of the optical application.The theoretical system is preliminarily formed for the optical characterization and evaluation of oil and gas.1.According to the response characteristics of oil-gas in optics,a series of spectrum methods are developed and gradually optimized which include linear regression,principal component analysis,cluster analysis,artificial neural networks,support vector machine and two-dimensional correlation spectroscopy.These methods are then applied in oil-gas detection,atmospheric pollution monitoring and urban livelihood areas.The related program and software are also finished.The basic principles and practical applications of these methods are written in a book called “The Spectrum Analysis Method of Terahertz spectroscopy” pressed by Science Press.2.Carbonates and carbonate rocks are investigated by using THz spectroscopy.Results show that carbonates have different absorption features in THz range,which is the base of reservoir evaluation.Meanwhile,for a general chemical reaction in geological evolution,the refractive indes spectra validate a common conservation relation that the average index of the reactants equal those of the products in the whole range.The results prove that atomic rearrangement process has different influence on the absorption and refractive response in THz range.3.The shape effect of micro-pore is investigated by using THz spectroscopy and relative spectrum analysis methods.The utilization of spectrum analysis methods can improve the imaging resolution from 150 μm to 20 μm.Therefore,spectrum analysis methods can extract the hidden information in the spectroscopy of optical parameters.4.THz spectroscopy is employed to investigate the absorption dynamics of water in porous active carbon.In the early diffusion stage,the optica parameters do not change;when absorption begins,THz parameters dramatically change until the end of adsorption.Consequently,THz spectroscopy can not only monitor the absorption dynamics,but also accurately determine the starting point,inflection and absorption rate in whole process.5.The surface properties of dense cores are investigated by using the OIRD technique.We discuss the dielectric distribution and observe that the shale has distinct texture or anisotropic characteristics and sandstone has isotropic properties.By the combination of optical microscope and scanning electron microscope,the micro-cracks and mineral distribution can be detected within the rocks.Therefore,OIRD is a very promising and practical technology for detecting the isotropy and anisotropy in rock and is a convenient supplementary technique for conventional methods.6.The optical response of surface sediment samples in an oil field in northwest China are studied by using THz spectroscopy.The amplitude attenuation coefficients per thickness are calculated and used for the distribution of THz resonse of oil and gas reservoirs in sampling areas.The above parameter is used as a basis to predict the distribution of organic matter,and the disbution of drilling locations is then obtained.The results are in agreement with the actual drilling and reflect high accuracy.