Channel Sands Genesis And Favorable Reservoir Prediction Of Toutunhe Formation At Cai 9 Well Area On Baijiahai High

The oil retesting at Toutunhe Formation in Cai9 well area in Baijiahai High in Junggar Basin unexpectedly gained a prolific well of 14.0t oil and 1200m3 gas per day in 2m of the reservoir,which opened up a new exploration situation.As it was lack of attention before,there remained several significant problems including scarcity of unified stratigraphic correlation principle in research area,shortage in cognition in channel sandstones genesis and distribution,deficiency in study in reservoir scale and favorability,which restricted the exploration and development of Toutunhe Formation in research area.On the base of system study on the role of Junggar Basin tectonic evolution in controlling the deposition of study area,applying high resolution sequence stratigraphy theory and detailed correlation technique,utilizing reservoir geology study method and analytic hierarchy process,this thesis emphasized on the comprehensive research on the genesis of channel sandstones and favorable reservoirs of Toutunhe Formation in study area.The results and conclusions were organized as follows:(1)Fine isochronous stratigraphic correlation method in fluvial sedimentary facies was summarized.The high resolution isochronous stratigraphic framework was established,in the overall controlling of long cycle and marked horizon,comprehensively applying the identification and correlation techniques of sequence stratigraphic base-levels and isoelevation method,and combining fluvial facies sedimentary models.The Toutunhe Formation was divided into 3 members which were systematic studied by using sequence stratigraphy.(2)Fluvial sedimentary features and sand-bodies genetic evolution were studied systematically,which were mainly controlled by rising and descending of the base level and local topography.In the situation that the basement subsided cyclic and source supply was decreasing overall,in the plane,braided rivers were tend to form at steep slope where the hydrodynamic force was strong,and the transformation of braided rivers to meandering rivers occurred where the grade eliminated for the weakening of hydrodynamic force;in the vertical,braided rivers mainly deposited where the base level was relatively low,and along with the rising of the base level,meandering rivers were beginning to develop.(3)Channel sandstones genetic type,scale and favorability of reservoirs were counted and summarized comprehensively.The genetic types of sand-bodies in a certain scale mainly included meandering channel,point bar,braided bar and braided channel.Advantaged oil testing sand-bodies were characterized by 3?5 meters.On the other hand,favorable reservoirs of exploration were sand-bodies in a large scale that were communicated by faults.(4)Advantaged areas in the research area were divided into two types,areas for exploration and areas for large scale oil testing,according to the different demands of oil field.The former were evaluated by reservoir analytical hierarchy process,and 5 areas suiting new well assessing were predicted.The latter used quantity of favorable oil testing sand-bodies in 3?5m as parameters to define 4 areas that were appropriate for recovered oil testing at the first time.Sedimentary system,distributary features of micro sedimentary facies,sand-bodies genesis characterization and regularities of distribution of favorable reservoirs of Toutunhe Formation were researched comprehensively in this thesis.That provided reliable basis for exploration of oil and gas reservoir in study area.