Research On Rock Physics Modeling And Organic Matter Prediction Of Shale Oil Reservoir

The development of unconventional oil and gas has triggered the revolution in the petroleum industry and changed the global traditional energy structure.Exploitation of unconventional hydrocarbon resources is of great significance to ensure security and helpful to maintain independence on energy.Organic rich mud shale is widely developed in China.Shale oil and gas resources have great potential and exploitation prospect.However,in shale-oil reservoirs,mineral composition is very complicated,laminated texture are well developed,poro-space are tiny,porosity and permeability are both very low and the feature of velocity anisotropy is very obvious.Those will lead to a great challenge to the evaluation of shale-oil reservoir using seismic forward modeling or inversion method.Thus,a new seismic rock physics model for shale-oil reservoir is needed to carry on rock physics analysis for acquisition of parameters needing in forward modeling and optimize sensitive seismic attribute,eventually play important guiding role for reservoir evaluation.Organic rich shales not only present anisotropy character of conventional mud shales—anisotropy heightens with increase of clay minerals or microcracks contents,but also show strong anisotropy caused by organic matters and it's maturity.The presence of organic matters makes strengthen the complexity of organic rich shale reservoirs.At present,most of the available isotropic rock physics model and some semiempircial is not enough to precisely characterize organic rich shale reservoirs.And quantitative characterization between rock physics properties of shale reservoirs and organic matters as well as maturity is also a challenge.Based on this reason,the modeling idea of this paper is improved through combining anisotropic rock physics theory by introducing organic matter maturity and orientation distribution considering two different occurrence states of organic matters.The new anistropic rock physics model for shale-oil reservoirs is carried out.The influence of various factors such as micro-geometrical structure,organic matter and organic pore and pore fluid on new rock physics model is studied.Finally,combined with the field data,the applicability and accuracy of the rock physics model are proved.Based on the anisotropic rock physics model,the crossplot of compressional wave velocity,shear wave velocity,density,lame constant,Young 's modulus and Poisson' s ratio is constructed,and the sensitive parameters are selected rationally to qualitatively predict organic matter.Finally,comparing the field data with modeling result,the accuracy of method is certificated and provides a new means for the evaluation of organic rich area.