A method for predicting the brittleness and fracture parameters of shale gas reservoirs based on prestack direct inversion
SHI Xue-Wen1,2, WANG Chang1,2, ZHANG Dong-Jun1,2, FENG Yan-Wen1,2
1. Shale Gas Research Institute, Southwest Oil & Gasfield Company,PetroChina, Chengdu 610051, China 2. Sichuan Key Laboratory of Shale Gas Evaluation and Exploitation, Chengdu 610051, China
目前常规各向异性介质的反演容易受小角度入射、地层弱性质变化的假设条件限制,并且岩石弹性参数的预测多通过线性反演弹性参数进而间接拟合得到,使得各向异性地层的岩石物理参数反演结果的精度与可靠性较低。为此,本文推导了具有垂直对称轴的横向各向同性(transverse isotropy with vertical axis of symmetry,VTI)介质杨氏模量、泊松比以及裂缝参数的岩石物理模型,基于精确VTI反射系数方程,提出了一种L1范数约束的贝叶斯各向异性非线性直接反演方法,用于对页岩气储层的脆性及裂缝参数进行直接反演预测。该方法在西南页岩气工区取得了良好的应用效果,为页岩气的储层表征提供了新的方法。
The conventional inversion of anisotropic media is often constrained by assumptions of narrow-angle incidence and weak changes in stratigraphic properties.Moreover,the prediction of rock elastic parameters typically involves linear inversion and indirect fitting,leading to less accurate and reliable inversion results of petrophysical parameters for anisotropic formations.Hence,this study derived the petrophysical models of Young's modulus,Poisson's ratio,and fracture parameters for vertical transverse isotropy(VTI) media.Based on the precise VTI reflection coefficient equation,this study proposed a Bayesian anisotropic nonlinear direct inversion method,constrained by the L1 norm,to predict the brittleness and fracture parameters of shale gas reservoirs through direct inversion.The proposed method yielded satisfactory application results in a study area of shale gas in Southwest China,offering a novel technique for characterizing shale gas reservoirs.
石学文, 王畅, 张洞君, 冯艳雯. 基于叠前直接反演的页岩气储层脆性及裂缝参数预测方法[J]. 物探与化探, 2025, 49(4): 826-837.
SHI Xue-Wen, WANG Chang, ZHANG Dong-Jun, FENG Yan-Wen. A method for predicting the brittleness and fracture parameters of shale gas reservoirs based on prestack direct inversion. Geophysical and Geochemical Exploration, 2025, 49(4): 826-837.
Dong D Z, Wang Y M, Li X J, et al. Breakthrough and prospect of shale gas exploration and development in China[J]. Natural Gas Industry, 2016, 36(1):19-32.
Zou C N, Yang Z, Cui J W, et al. Formation mechanism,geological characteristics and development strategy of nonmarine shale oil in China[J]. Petroleum Exploration and Development, 2013, 40(1):14-26.
[3]
Zong Z Y, Yin X Y, Wu G C. Elastic impedance parameterization and inversion with Young's modulus and Poisson's ratio[J]. Geophysics, 2013, 78(6):N35-N42.
[4]
Grana D. Bayesian linearized rock-physics inversion[J]. Geophysics, 2016, 81(6):D625-D641.
[5]
de Figueiredo L P, Grana D, Bordignon F L, et al. Joint Bayesian inversion based on rock-physics prior modeling for the estimation of spatially correlated reservoir properties[J]. Geophysics, 2018, 83(5):M49-M61.
[6]
Chen H Z, Innanen K A, Chen T S. Estimating P- and S-wave inverse quality factors from observed seismic data using an attenuative elastic impedance[J]. Geophysics, 2018, 83(2):R173-R187.
[7]
Zhang F, Li X Y. Generalized approximations of reflection coefficients in orthorhombic media[J]. Journal of Geophysics and Engineering, 2013, 10(5):054004.
[8]
Sondergeld C H, Rai C S. Elastic anisotropy of shales[J]. The Leading Edge, 2011, 30(3):324-331.
Zhang G Z, Chen J J, Chen H Z, et al. Prediction for in situ formation stress of shale based on rock physics equivalent model[J]. Chinese Journal of Geophysics, 2015, 58(6):2112-2122.
Liu J W, Zhang Y Y, Zeng L B, et al. Geophysical prediction of stress and stress desserts in unconventional reservoirs:An example in Bonan area[J]. Oil Geophysical Prospecting, 2016, 51(4):792-800,7.
[11]
Plessix R E, Bork J. Quantitative estimate of VTI parameters from AVA responses[J]. Geophysical Prospecting, 2000, 48(1):87-108.
Hou D J, Liu Y, Ren Z M, et al. Multi-wave prestack joint inversion in VTI media based on Bayesian theory[J]. Geophysical Prospecting for Petroleum, 2014, 53(3):294-303.
doi: 10.3969/j.issn.1000-1441.2014.03.007
[13]
Lu J, Wang Y, Chen J Y, et al. Joint anisotropic amplitude variation with offset inversion of PP and PS seismic data[J]. Geophysics, 2018, 83(2):N31-N50.
[14]
Lang K, Yin X Y, Zong Z Y, et al. Anisotropic nonlinear inversion based on a novel PP wave reflection coefficient for VTI media[J]. IEEE Transactions on Geoscience and Remote Sensing, 2023,61:5913613.
[15]
Bakulin A, Grechka V, Tsvankin I. Estimation of fracture parameters from reflection seismic data,Part II:Fractured models with orthorhombic symmetry[J]. Geophysics, 2000, 65(6):1803-1817.
[16]
Schoenberg M. Elastic wave behavior across linear slip interfaces[J]. The Journal of the Acoustical Society of America, 1980, 68(5):1516-1521.
[17]
Schoenberg M. Reflection of elastic waves from periodically stratified media with interfacial SLIP[J]. Geophysical Prospecting, 1983, 31(2):265-292.
[18]
Zoeppritz K, Erdbebnenwellen V. On the reflection and penetration of seismic waves through unstable layers[J]. Gottinger Nachrichten, 1919(1):66-84.
[19]
Rüger A. Reflection coefficients and azimuthal AVO analysis in anisotropic media[M]. Tulsa: Society of Exploration Geophysicists, 2002.
[20]
Graebner M. Plane-wave reflection and transmission coefficients for a transversely isotropic solid[J]. Geophysics, 1992, 57(11):1512.
