Study On Percolation Mechanism In Deep-buried High-pressure Low-permeability Reservoir

At present, the world’s oil industry is faced with severe challenges. On the one hand, the new exploration area is decreasing quickly and the backup reserves is less and less and the most new proven geological reserves is in the low permeability oil field; on the other hand, the low permeability oilfield development effect and the economic benefit is low.The gap of understanding and development level for between low permeability reservoir and high permeability reservoir is tremendous. In order to develop low permeability reservoir and extra low permeability reservoir reserves, it is necessary to understand the characteristics of low permeability reservoir, percolation mechanism, constraining the solution of these reserves.This paper studies the deformation mechanism, starting pressure gradient, stress sensitivity of deep-buried high-pressure low-permeability reservoir and explored the percolation law in low permeability reservoir Orthogonal optimization method and numerical simulation technology was used in high pressure and low permeability reservoir and remaining oil tapping measures was suggested according to development and fracturing parameters. Considering the visitor characteristics of strata, the variable permeability productivity prediction model was established. Considering the joint surface pollution, the quantitative impact factors and the nonlinear phenomena in high pressure and low permeability reservoir was checked. The relationship between the starting pressure gradient and the output of oil wells and the low permeability reservoir vertical cracks was optimized. This makes the theory on the mechanism of deep-buried high-pressure low-permeability reservoir richer and deeper and more perfect system. A good effect was achieved when this study results was used in wenxi block13 in Zhongyuan Oilfield and it also could be referenced for similar reservoir development. The main results are as the following:1. Reservoir deformation mechanism, starting pressure gradient and stress sensitivity of the deep-buried high-pressure low-permeability reservoir studied was made and factors on seepage rule and the influence of low permeability reservoir was examined.2. The prediction formula was established considering capacity sensitive and start-up pressure gradient.3. To analyze the crack distribution effect on well productivity and the influence factors of the fractured wells productivity.4. Using the orthogonal optimization method to determine the different permeability of the optimal well and fracturing parameter.5 According to the crack surface pollution, the affecting productivity factors and the nonlinear phenomena, starting pressure gradient and the output of oil well was analyzed and the low permeability reservoir vertical cracks was optimized.6. Measures were suggested to be used in block13 Wendong oilfield and valid.