库车坳陷K区块冲断带深层白垩系致密砂岩裂缝发育规律、控制因素与属性建模研究

A study of fracture development,controlling factor and property modeling of deep-lying tight sandstone in Cretaceous thrust belt K region of Kuqa depression

针对致密砂岩气藏裂缝预测的复杂问题,本文以库车坳陷K区块为例,提出基于裂缝精细描述的属性建模方法,为该区裂缝预测提供新思路。首先基于岩心和成像测井裂缝解释模型,采用网格法获取裂缝参数,包括裂缝延伸长度（2～1850mm）、裂缝密度（平均值0.53条/米）、裂缝宽度（集中分布在0.1～0.4mm）、倾角（56°～82°）及面缝率（0.016%～0.083%）。该区影响裂缝发育的主要因素有构造、层厚以及埋深。不同构造部位裂缝发育规律不同：背斜核部发育张裂缝,其宽度和长度呈高值;翼部主要发育X剪裂缝,宽度、长度和密度都处于相对低值;近断裂附近发育高角度裂缝,密度呈高值。层厚与裂缝密度及面缝率成反比。K区目的层是深-超深埋深,随着埋深的增加,矿物脆性减弱韧性增强,超过临界点（7100m）裂缝的发育逐渐减弱。应用Petrel软件,利用裂缝精细描述数据库、构造数据和层面数据等,实现裂缝密度和面缝率模型的建立。最后,探索性的研究裂缝参数和渗透率的相关性,通过裂缝密度参数拟合渗透率模型,实现K区块的渗透率定量预测。

In order to find out a solution of fracture prediction of tight sandstone gas reservoir. The paper taking the K region of Kuqa depression as an example,provides a method of property modeling which is based on the elaboration of nature tight sandstone,and offer a new thought of fracture prediction. First,based on the explained model of core and imaging logging,the research obtains a large amount of fracture parameter data by grid method,including fracture extension length（ 2 ~ 1850mm）,fracture density（ avg.0. 53 / m）,fracture width（ concentrated distribution 0. 1 ~ 0. 4mm）,dip angle（ 56° ~ 82°）,and fissture＇s area rate（ 0. 016% ~0. 083%）. Structure parts vary mainly because of the different of geologic structure,layer thickness and strata depth. The development regularity of fractures is different in different tectonic position. The tension fractures are longer and wider in anticlinal core,while X fractures developed in flank of anticlinal are short,narrow and sparse,and the high angle fracture＇s density is higher near fault point.Layer thickness causes that the fractures in thin layer,moderately thick layer,thick layer and blocky layer decrease in turn. Mineral brittleness decreases toughness enhancement of aiming formation（ 〉6000m） in K region with the burial depth increasing. When more than critical point（ 7100m）,the development of the fractures weakens gradually. Under the basic study of elaborate fracture data,structure data and level data,the research builds the model of fracture density and fissure＇s area rate with Petrel. At last,research makes an exploratory study of the correlation between fracture and permeability,and achieve to a quantitative prediction of permeability in K region through fracture parameter fitting permeability models.