Research On Prediction In Fractured Reservoir

Seismic prediction of fractured reservoir was difficult and hot part in geophysical prospecting. With the progress of oil and gas exploration,fractured reservoir became irrevocable than anytime before. Carbonate rock dominates fractured reservoir, cracks are also in the mudstone, volcanic and metamorphic rocks. As an important storage space, the authorities have not an ideal method for investigation on fracture prediction. It existed forecasting techniques which including seismic prediction, logging recognition, stress analysis, etc. These forecasting methods have advantages and disadvantages when applied into practice.In this paper, the essence is the prediction of reservoir fracture which is based on previous researches. It is in accordance with datum of dolomite reservoir in the Jialingjiang No.2 member of District A in the Northeast Sichuan Basin. The research of this topic followed by a set of research methods and the prediction techniques are established by fractured reservoir. It consists of the following aspects:1) Studies on the reservoir of the Jialingjiang No. 2 member. The geological background of work area is analyzed by the structural evolution, structural characteristics, and formation characteristics. In addition, it analyzes the characteristics of rock, reservoir space types and seismic response characteristics of reservoir. It determines the reservoir space of the Jialingjiang No.2 member which belongs to fractured-porous.2) Crack distribution is studied by azimuthal anisotropy of P wave when it advocates in fractured media. Firstly, petro physical model is established. It analyzes affects of azimuthal anisotropy which is caused by crack density and hydrocarbon bearing in reservoir fracture section. And it determines the seismic response characteristics of reservoir crack segment. Through the azimuthal anisotropy pushes forward study of reservoir, it determines the direction of crack development. Secondly, apart from azimuthal anisotropy pushes forward study of the reservoir, the lateral distribution of fractures of the Jialingjiang No.2 member reservoir is predicted by P wave azimuthal anisotropy.3) Structural deformation is the one of the essence elements which caused cracks while the structural deformation analysis aiming to analyze the distribution of stress field. Combined with reservoir structure, the lithologies, thickness, fracture system of the Jialingjiang No.2 member, and the principal strain and principal stress are calculated by Structural Mechanics. Based on the analysis of stress field, corresponding laws are completed between the stress distribution and crack development, then analyzing those geological factors causing cracks.4) Based on prediction of reservoir fracture, the favorable reservoirs containing oil and gas are detected by the characteristics of the high-frequency attenuation and low frequency. That enhance when P wave propagates in reservoirs containing fluid or gas. As is known, it tests the validity and reliability of using the characteristics of low and high frequency changes when detecting oil and gas. It further detects the favorable range of reservoir of the Jialingjiang No.2 member from the plane. These ideas and results are of great value and practical significance for further exploration and development of this region and even such reservoirs.