In The Central Tarim Card A Block Of Ordovician Sedimentary Characteristics And Reservoir Evaluation Study

Based on the theory of sequence stratigraphy, the paper aims to study favorable reservoir in Ordovician of Ka 1 block in Tarim basin, which comprehensively uses various data such as seismic and well-logging data.On the basis of the former achievements, the author makes divisions of Ordovician sequence stratigraphy of Ka 1 block, by making full use of the 2-D seismic profiles in Ka 1 block, and builds up the Ordovician general sequence stratigraphic framework. The Ordovician formation of the project area can be divided into seven sequences, i.e. Sql, Sq2, Sq3, Sq4, Sq5, Sq6 and Sq7. And four sequences: Sql-Sq4 in yingshan formation, middle-lower Ordovician includes dolomite, limy dolomite, dolomitic limestone and limestone, the sea level was rising to falling; Sq5-Sq7 belong to lianglitage and sangtamu formation in upper Ordovician, and include carbonates from limestone to pelitic limestone, and second pelitic limestone, limestone. The characteristic of sea level is from rising to falling, rising to falling again. Similarly ka 1 block can be divided into two super sequences include Sql-Sq4 and Sq5-Sq7. Through combination of well and seismic and by means of well connection contrasts, the author also describes the developing characteristics of all the sequences detailedly.We identify the precipitation facies: the tidal-flat platform, the restricted platform, the open platform, the shelf facies in Ordovician of Ka 1 block in Tarim basin. Ordovician is generally an inundation phase. Through the longitudinal evolvement process, the tidal-flat platform, the restricted platform, and the open platform, are developed in Ordovician of Ka 1 block from bottom to top, and evolved into the shelf facies gradually. For study of sequence stratigraphic framework and reservior system, the author points out the features and distribution of depositional system are strictly controlled by the sea level change, palaeostructure and palaeogeography.Combined with such as the seismic, well-logging data, core, FMI imaging logging data, the paper evaluates the reservoir of Ordovician in Ka 1 block, and designates tow type reservoir rock: dolomite, limestone and four type reservoir:dissolution-void reservoir, dispersive fracture reservoir, fracture-void reservoir, vertical fracture reservoir. Thereinto, dolomite of middle-lower Ordovician reveals be mostly fracture reservoir, limestone of upper Ordovician reveals be mostly dissolution reservoir. Fracture effect in middle-lower Ordovician in Ka 1 block can be divided three phases and this three phases fracture strengthen effect of fracture, dissolution effect in upper Ordovician in Ka 1 block also can be divided three phases and this three phases dissolution strengthen effect of dissolution. Taking one with another, reservoir of Ordovician in Ka 1 block is better, the favorable reservoir distributes around the center fault zone and the I fault zone be controlled by structure. There are three configurations among reservoir and cap in Ordovician in Ka 1 block: the configuration of among middle-lower Ordovician, the configuration of carbonates in middle-lower Ordovician and marlite in upper Ordovician and the configuration of plateform facies carbonates in upper Ordovician and the marlite in overlay stratigraphy on upper Ordovician.