Title

Quantitative comparison of the influence of porosity and pore structure on reservoir characteristics

单位

(1.成都理工大学地球勘探与信息技术教育部重点实验室,四川成都610059;2.成都理工大学油气藏地质及开发工程国家重点实验室,四川成都610059)

Organization

(1.Key Laboratory of Earth exploration and Information Techniques of Ministry of Education,Chengdu University of Technology,Chengdu 610059,China;2.State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Chengdu University of Technology,Chengdu 610059,China)

摘要

岩石孔隙度和孔隙结构是表征储层渗、储属性的重要参数,这些参数在含流体岩层的岩性识别和油气预测中具有关键作用。首先探讨了孔隙结构参数的含义及其数学表示,再利用与孔隙度和孔隙结构有关的岩石骨架模型替代常规Gassmann流体方程中不含孔隙结构的岩石骨架模型,形成了可定量计算孔隙度和孔隙结构参数的扩展Gassmann方程;然后推导出孔隙度和孔隙结构对储层有效弹性属性影响的定量公式,获得了度量孔隙度和孔隙结构对储层弹性性质的影响因子R,为定量比较二者对储层属性的影响奠定了理论基础。理论分析和数值模拟计算表明:当R值适中时,孔隙度和孔隙结构对储层弹性性质的影响相当;R较大时,孔隙结构的影响大于孔隙度的影响;R较小时,孔隙度的影响大于孔隙结构的影响。这为储层评价和分析提供了定量方法和依据。以常用的Keys-Xu模型作为对比,计算了储层纵、横波速度随孔隙度和孔隙结构的变化,结果显示:孔隙度和孔隙结构均可使岩石的纵、横波速度的最大变化量达到2 000~3 000 m/s,变化规律与影响因子R的结果一致,验证了扩展Gassmann方程和定量比较方法的正确性与适用性。

Abstract

Rock porosity and pore structure are important parameters representing reservoir fluid permeating and reserving properties,and they play a key role in lithologic identification and oil and gas prediction in fluid-saturated rock.However,there is little quantitative research on the influence of pore structure on the elastic properties of reservoirs,and little quantitative comparison of the influence of porosity and pore structure on rock elasticity.To this end,this paper first discusses the meaning and mathematical expressions of pore structure parameters.Then,it uses a uniform rock frame model with porosity and pore structure parameters to replace the conventional model,and obtain an expanded Gassmann equation to calculate porosity and pore structure parameters.A quantitative formula of influence of porosity and pore structure on reservoir effective elastic properties is then deduced.Using theoretical analysis and numerical simulation,the influence factor R,of porosity and pore structure on the elastic properties of reservoirs,are obtained.When the value of R is middling,porosity and pore structure have an equal influence on the elastic properties of the reservoir.When R is larger,pore structure has a greater influence than porosity.When R is small,porosity has a greater influence than pore structure.As a comparison the Keys-Xu model is used to calculate the changes in the velocities of P-and S-waves with data on porosity and pore structure in a reservoir.The results show that the porosity and pore structure can make P-and S-wave velocities change by 2 to 3 km/s maximally,which is consistent with trends in the influence factor R.This verified the validity and applicability of the formula and method presented in this paper.

关键词：

孔隙度与孔隙结构; 储层属性; Gassmann方程; 定量比较; 影响因子;

Keywords:

porosity and pore structure,; reservoir properties,; expanded Gassmann equation,; quantitative comparison,; influence factor;

基金项目

国家自然科学基金(41374111,41404101,41174114)和国家科技重大专项(2011ZX05023-005-010)联合资助。

DOI

10.3969/j.issn.1000-1441.2018.02.002

孔隙度和孔隙结构对储层特性影响的定量比较