和田河气田碳酸盐岩储集层的岩溶作用

Karstification of Carbonate Reservoir in Hetian River Gas Field of Tarim Basin

和田河气田是塔里木盆地最近探明的大型碳酸盐岩气田,主要储集层为奥陶系潜山灰岩和石炭系生屑灰岩,岩溶作用十分发育。根据各类岩溶发生的时间、机理和部位的研究认为,岩溶作用主要发育有三种:层间岩溶、风化壳岩溶和埋藏岩溶。层间岩溶和风化壳岩溶由大气淡水作用形成,奥陶系潜山灰岩埋藏岩溶由有机酸作用而成,石炭系生屑灰岩埋藏岩溶由硫酸溶蚀形成。岩溶作用主要受控于岩性、构造、古地貌和古气侯,岩溶作用可提高储集层孔隙度和渗透率。

Hetian river gas field,a large-scale carbonate gas pool recently found or proved in Tarim basin,is well-developed in karstification for its major reservoirs such as Ordovician buried hill limestone and Carboniferous bioclastic limestone.Based on the time,location and mechanism of each type of karsts,the primarily developed karstifica tions in- clude interlayer karst and weathering crust karst formed by atmospheric fresh water process as well as buried karst,of which Ordovician buried hill karst was formed by organic acid action,while Carboniferous bioclastic limestone buried karst by sulfidation dissolution.The karstification is mainly controlled by lithology,structure,palaeogeomorphology and palaeoclimate,and it could improve porosity and permeability in the carbonate reservoir.