准噶尔盆地阜东斜坡区头屯河组储层特征及敏感性

Characteristics and sensitivity of the Middle Jurassic Toutunhe Formation in Fudong slope,Junggar Basin

基于岩心观察描述、铸体薄片鉴定,辅以扫描电镜、物性、X-衍射、孔隙结构和敏感性等岩心分析化验等资料,对准噶尔盆地阜东斜坡区头屯河组储层特征、控制因素及敏感性进行研究。结果表明,最有利储层发育的沉积微相为三角洲前缘水下分流河道,岩性以成分成熟度低,而结构成熟度中等偏高的长石岩屑砂岩为主,储集空间主要为剩余原生粒间孔,少量为粒间和粒内溶孔;排驱压力和饱和度中值压力偏低,孔喉分选性较好,总体喉道偏细,以毛细管喉道为主;储层发育受沉积微相和成岩作用综合控制,成岩早期的环边绿泥石胶结作用有利于部分原生孔隙和喉道的保存,压实-压溶作用使原生孔隙空间不断缩小,储层孔隙渗透性降低,岩石致密。并且头屯河组砂岩储层普遍具备各种敏感性,是造成储层损害的主要原因之一,其中对储层伤害最强的是中等偏强的水敏性,次为中等偏弱的酸敏性和盐敏性,而弱速敏性对储层基本无伤害。

The reservoir characteristics,controlling factors and sensitivities of the Middle Jurassic Toutunhe Formation in Fudong slope,Junggar Basin,were studied based on core observation,casting thin section identification,assisted with some analytical and experimental data on cores,such as SEM data,physical property depiction,x-ray diffraction results,pore structure and sensitivity test. Results show that：（ 1） the most favorable micro-facies for reservoir development is underwater distributary channel at delta front and its lithology is mainly composed of feldspathic litharenite that is low in compositional maturity and medium high in textural maturity. The reservoir space is mainly primary residual intergranular pores,partly intergranular and intragranular dissolved pores;（2） displacement pressure and mean saturation pressure are relatively low,but the pore throats are well-sorted,narrow as a whole,and are dominated by capillary throats;（3） reservoir development is controlled by both sedimentary microfacies and diagenesis;the early diagenetic chlorite rim cementation is beneficial to the preservation of some primary pores and throats,but compaction and pressure-solution causes the shrinkage of the primary pore space,the lowering of reservoir permeability,and the tightening of reservoir rocks. In addition,the sandstone reservoirs of the Toutunhe Formation generally have various sensitivities,which is one of the main causes of reservoir damage. Among them,the medium strong water sensitivity is the strongest in reservoir damage,followed by the medium weak acid sensitivity and salt sensitivity,while weak velocity sensitivity is hardly harmful.