川东北板东地区长兴组生物礁型储层研究

四川盆地东北部板东地区长兴组地层主要由含生物(屑)灰岩-生物(屑)灰岩、礁灰岩、泥-粉晶白云岩和细-中晶白云岩构成,其中以细-中晶白云岩的储集性能最好。以礁顶部测井曲线变化特征为依据,认为该礁至少是由3个旋回叠加而成。成岩作用中对储层影响最大主要是胶结充填作用、白云石化作用、溶蚀作用。经镜下观察认为胶结充填作用分3期,充填了大部分的原生孔隙;混合水云化作用使生物屑灰岩演变成具或不具生物(屑)残余结构的细—中晶白云岩;溶蚀作用形成的晶间溶孔、不规则溶孔、溶洞构成了生物礁主要储集空间。

Study on organic reefs-type reservoir at Changxing formation of east Banqiao area in east-north Sichuan

Changxing formation of east Banqiao area in east- north Sichuan is mainly composed of bioclastic limestone, reef limestone,putty-powder crystal dolomite and fine- medium crystal dolomite,among which medium crystal dolomites are preferential to form good reservoirs.Ac- cording to curves analysis of reef crest,the reef is consid- ered to be superposed through at least three sedimentary cycles.The diagenesis such as cemented filling,dolomiti- zation and dissolution play a crucial part in reservoir for- mation.Through eletro-microscope observation,the ce- mented filling is thought to be three-period with primary porosity mostly filled in,bioclastic limestone is evolved into fine-medium crystal dolomite by mixed water dolo- mitization,while the intercrystalline-dissolved pores,ir- regular dissolution pores and cave generated from dissolu- tion become main reservoir spaces.