成層性頁巖儲層巖石物理建模與指示因子反演

中圖分類號：P631 文獻標識碼：A DOI：10.13810/j.cnki.issn.1000-7210.20240322

Abstract： With the advancement of geological theory and geophysical prospecting technology， shale reservoirs haveemerged as the crucial target ofoiland gas explorationand development.Research indicates that the development of lamination or stratification can conspicuously enhance the physical property conditions of the reservoir.Drilling outcomes also afrm that stratification characteristicssuch as the density oflamination tend to determine the development of oil and gas.Nevertheless，the study of laminationor stratification remains in its nascent stage.Therefore，it holds significant importance for the characterization of shale reservoirs to clarify the micro rock physical mechanism for shale stratification and search for inversion parameters directly characterizing the stratification.Based on the prevailing rock physics theory，the stratification inducing factors，such as lamination density，mineral shape，and random arrangement of clay blocks，are studied respectively. The coresponding rock physical models of each factor are summarized and the degree of influence is analyzed.On this basis，ashalerock physical model consideringstratification is establishedandsuccesullyappliedto theshear wave prediction of actual logging data. To achieve the direct inversion of shale stratification characteristics，the stratification indicators are constructed by employing the concept of upper and lower limits in rock physics and utilized as the criterion to measure the stratification.At the same time，the elastic impedance form of three approximate equations of reflection coeficients ofVTI media is derived.The relationship between the stratification indicators and the model parameters in the equation is retrieved by a machine learning algorithm，thereby enablingthe stable inversion of the stratification indicators. The application ofthe actual data demonstrates that the inversion results are in excellent agreement withthe actual driling，which efectivelydelineates the distribution of the reservoir and is conducive to guiding the horizontal evaluation of the shale reservoir. Keywords：shale rock physics，VTI media，stratification，pre-stack inversion

吳思，楊柳鑫，孫正星，等，成層性頁巖儲層巖石物理建模與指示因子反演[J].石油地球物理勘探，2025，60（4）：1020-1031.

WU Si，YANG Liuxin，SUN Zhengxing，et al.Stratification shale reservoir rock physics modeling and indicatorinversion[J].Oil GeophysicalProspecting，2025，60（4） ：1020-1031.

0 引言

頁巖是非常規(guī)油氣藏的重要研究目標。與砂巖儲層不同，頁巖是黏土礦物經(jīng)壓實、脫水和重結晶作用形成的[1]，其特殊的巖石物理性質(zhì)使得常規(guī)解釋手段無法滿足頁巖儲層勘探的實際需求。地震巖石物理模型建立了宏觀彈性參數(shù)與微觀物性參數(shù)之間的定量關系，是實現(xiàn)疊前地震反演的基礎，近年來針對頁巖的巖石物理建模也成為了專家學者的研究重點[2]。頁巖基質(zhì)中包含多種礦物成分且孔隙結構較為復雜，基質(zhì)礦物的彈性屬性、連通性及體積分數(shù)控制著頁巖整體的彈性特性[3-4]。同時，由于紋層或層理的廣泛發(fā)育以及黏土、干酪根等礦物的定向排列，頁巖儲層的背景通常具有明顯成層性特征，微觀上表現(xiàn)為垂直橫向各向同性（VerticalTransverselyIsotropic，VTI）性質(zhì)。上述因素給頁巖精細巖石物理建模帶來了挑戰(zhàn)，如何通過巖石物理模型理清成層性和巖石彈性、物性間的關系是研究頁巖儲層的基礎。

頁巖儲層的建模過程，其本質(zhì)上是對巖石各向異性或成層性的合理描述。除裂縫因素外，造成地下介質(zhì)各向異性的原因主要可以分為： ① 不同巖性層的疊加分布[5-]； ② 基質(zhì)礦物的定向排列[8-9]，上述引起各向異性的因素在頁巖中尤為常見。在早期研究中，各向同性VRH模型被用于計算頁巖基質(zhì)的等效模量[10]，這顯然不符合頁巖的各向異性特征。……