塔河油田奥陶系储层研究

通过钻井岩心和铸体薄片观察，根据下奥陶统灰岩基质的孔渗特征和孔隙结构特征，并与基质作为储层的下限对照裂隙、洞穴和溶蚀孔洞不发育的灰岩基质，发现尽管有微孔隙的发育，但其孔隙度、渗透率、最大孔喉半径、饱和度、中值喉道半径等参数值远低于储层下限值，基本不具备储集和生产油的意义。而下奥陶统灰岩段储集和生产油气的有效储渗空间按成因、形态及大小可划分为溶蚀孔隙、溶蚀孔洞、大型洞穴、风化裂隙、构造裂隙等5类，构成5种性质有别的储层，即洞穴型储层、风化裂隙型储层、构造裂隙型储层、台缘滩相颗粒灰岩溶蚀孔隙型储层和地表残积物裂隙-孔隙（洞）型储层。从而使塔河油田奥陶系储层有了一个比较系统、完善的划分标准。研究和搞清这些有效储层的成因及分布规律，对塔河田区奥陶系的油气勘探开发至关重要。

ORDOVICIAN RESERVIORS OF TAHE OIL FIELD

Observation of drilling cores and casting-sections and the characters of pore structures and permeability of the matrix of the lower- Ordovician carbonate in comparing with the lower limit of a reservoir for matrix reveal that the porosity, permeability, maximum pore diameter, saturation and median throat diameter in the matrix with undeveloped fissures, holes and solution pores are far lower than those of a reservoir limit although some micro-pores are developed in the matrix which therefore has no capacity of storing and producing oil-gas. The favorable reservoir spaces in the carbonate rock could be divided into five types according to their origin, configuration and size, i.e., solution fissure, solution hole, cave, erosional fissure and structural fissure, which form five different reservoirs including cave-type reservoir, erosional fracture reservoir, structural fissure reservoir, and solution pore marginal beach grainstone reservoir. A systemic and integrated criteria is thus obtained for the Ordovician carbonates in the Tahe oilfield. It is very important for the exploration and development of oil-gas to study and clarify origin and occurrence of these favorable reservoirs.