Production Characters Of Crevice-Cave Unit And Modes Of Oil And Water Contact In Ordovician Reservoir At Block 4 In The Tahe Oil Field

The Tahe reservoir Ordovician carbonate rock is a special reservoir. Thecarbonate reservoir rock includes many influence factors that is through many phasesstructure bursts and the ancient karst to act on jointly the formation. The complicatedoil field of karst cave and crack is controlled by limestone reservoir and thecrevice-cave system, which has many characteristics such as great in style, irregulardistribution, the limestone cave in crack and unhomogeneity of rock etc. These kindsof reservoir belong to a world difficult and extreme problem on searching andexploitation. So, in the process of exploratory development, it has very importanttheoretic and practical values that identifying the caves and crevices, analyzing andevaluating the communications of caves and crevices, researching the oil and water'sconnection, and establishing the modes of oil and water's contact, to make andregulate the development programs of the carbonate oil reservoirs.Because of the Tahe reservoir's special character, this paper basing on the"crevice-cave unit" theory, has established the vertical and plane distributions of thecrevice and cave, and delimited the reservoir's beneficial vegetal areas, by analyzingthe quiescent geologic communication, with this reservoir's many information such asgeologic, core, logging, seismic, part of predecessors' outcomes. Then associating theproduction data, this paper has divided this reservoir 29 crevice-cave units which isthe basic unit of the reservoir's development, with the methods of pressure analyzing,interference testing, production character and oil property. Using the well's testingand pressure data, this research has defined the units' original oil-water interface withmanifold methods, suspecting that the original oil-water interfaces of each unit aren'tunified, and in a unit there also has more than one interface because of the probablyexistent divided waters which are developed by the complicate geological structure.On the bases of crevice and cave's identification, communication's analysis, using thedata of seismic, production performance, production logging, water ion's analysis etc,this paper has researched the oil and water's connections of single-well unit and multiwell units, and rendered four new modes, which is fit for the practice and favour ofthe crevice-cave unit's development.