鄂爾多斯盆地喬川一元城地區長8儲層特征及主控因素

中圖分類號：P618.13 文獻標志碼：A 文章編號：1003-5168（2025）14-0107-06

DOI：10.19968/j.cnki.hnkj.1003-5168.2025.14.021

Reservoir Characteristics and Main Controlling Factors of Chang 8 in theQiaochuan-Yuancheng Area of the ErdosBasin

TIANTian1 WU Guorong1 LYUNana1 LIN Li1 ZHAIWenbin2.3 （1.The Tenth Oil Production Plant of Changqing Oilfield Company， China National Petroleum Corporation， Qingcheng 7451Oo，China; 2.School of Earth Science and Engineering，Xi'an Shiyou University，Xi'an 710065， China; 3.Shaanxi Key Lab of Petroleum Accumulation Geology，Xi'an Shiyou University， Xi'an 710065， China）

Abstract： [Purposes]To clarify the basic characteristics and main controlling factors of the Chang 8 reservoir in the Qiaochuan-Yuancheng area of the Ordos Basin，and to provide a more accurate geological basis for oil and gas exploration and development in the region.[Methods]By using experimental methods such as rock cast thin sections，scanning electron microscopy，and high-pressure mercury injection， the characteristics of the reservoir were analyzed，clarifying the basic features and main controlling factors of the reservoir.[Findings] The results indicate that the Chang 8 reservoir mainly consists of lithic feldspar sandstone and feldspar lithic sandstone.It belongs to an ultra-low porosity and ultra-low permeability reservoir， with complex pore structures and relatively low pore content.The microstructure character-istics of mercury intrusion show that the pore structure isrelatively poor，dominated by fine throats.[Conclusions] Through analysis，it is concluded that sedimentation provides the the foundation forhigh-quality reservoir development， with such reservoirs primarily forming in underwater distributary channel microfacies of delta-front sedimentary subfacies.Compaction and cementation，as the primary destructive diagenetic processes，degrade reservoir properties.And dissolution，as the main constructive diagenesis，improves the physical properties of reservoirs by forming secondary pores ， which is the main factor in the formation of high-quality reservoirs.

Keywords： Ordos Basin; Chang 8 reservoir; sedimentation; diagenesis; structural function

0 引言

鄂爾多斯盆地延長組長8段是重要的油氣儲集層。近年來，隨著勘探技術的進步和對地質認識的不斷深化，對于長8儲層的研究也逐漸深入。由于長8儲層具有超低孔一超低滲的特點，微觀孔隙結構復雜且受到多種地質因素的共同影響，其儲層發育程度和物性特征仍需進一步探究[1]。本研究通過對巖石類型、物性特征、微觀孔隙類型，以及壓汞微觀結構特征等方面的詳細分析，揭示了長8儲層的基本特征及其孔隙結構的復雜性。同時，從沉積作用、成巖作用和構造作用等方面探討了儲層發育的主控因素，明確了這些因素對儲層物性及時空分布的影響，深化對鄂爾多斯盆地喬川一元城地區長8儲層的認識，為該地區的油氣勘探與開發提供地質依據。

1 區域地質概況

鄂爾多斯盆地喬川一元城地區位于陜北斜坡西部，區域構造表現為一個大型的、向西傾斜的平緩單斜[3。晚三疊世延長組自下而上共發育了長1至長10油層組，其中長8段主要發育三角洲前緣沉積亞相。三角洲前緣是河流進人湖泊后，由于水流速度減緩，沉積物逐漸堆積形成的區域。這種沉積環境有利于形成優質的儲層砂體，例如，水下分流河道砂體。水下分流河道砂體具有分選性好、雜基含量低的特點，有利于形成良好的原生粒間孔和剩余粒間孔，為油氣的儲存提供充足的空間[2]。良好的地層發育情況和有利的沉積相特征，這些因素共同為該地區的油氣勘探與開發提供了重要的地質基礎。……