| The reservoir in the 8 formation of southern Tuo 11 block is highly exploited and has now entered a very high water cut period.At present,there are problems such as the spatial distribution of permeability barrier is unclear,the permeability characteristics of permeability barriers determined the movement characteristics of oil and water,which control the distribution of remaining oil.Therefore,the study of permeability barriers can provide a basis for tapping potential of remaining oil.The permeability barriers in the studied area can be divided into argillaceous style,calcareous style,and petrophysical style according to the lithology based on the data of well cores,well logging,and development dynamics.The petrophysical characteristics and sedimentary origins of different lithologic permeability barriers are summarized,and the qualitative identification maps in well logs are established for different lithologic permeability according to the characteristics of well logging response.The permeability barriers are divided into interlayers of permeability barriers,inner layers of permeability barriers and permeability in the sandbodies according to the principle of sequence stratigraphy.The position,occurrence,thickness,distribution range and continuity of different orders of permeability barriers are summarized.The well logging response maps are used to identify the permeability barriers in the single well,and the development dynamic data are used to determine the distribution range of permeability barriers.The interlayers of permeability barriers are of the most areal extent,the inner layers of permeability barriers take the second place,and the permeability barriers in the sandbodies is of the minimum.Analyzing the frequency and density of permeability barriers,we know that the permeability barriers in 83 single layer are of the most thickness,the permeability barriers in 83 single layer are most stable in quantity.The thickness of permeability barriers are within a limited range in 81 and 83 single layers,while the thickness of permeability barriers are of evident difference in the south and north of 82 single layer.The characteristics and differences of reservoirs before and after flooding of well logging response were summarized,that the physical property improved,the wettability moved to water-wet,the average pore-throat radius increased after flooding.In terms of the well logging response,AC value increased,GR,DEN,RT value decreased.The role of different orders of permeability barriers in controlling the movement of oil and water was clarified,that the interlayers of permeability barriers mainly block the fluid vertically,the fluid moves along the permeability barriers,and the remaining oil concentrates under the interlayers of permeability barriers;the inner layers of permeability barriers is oblique,and block the fluid horizontally,the remaining oil concentrates in the corners of the sand bodies;the blocking of the permeability barriers in the sandbodies is not effective,which leads to the sporadic distribution of remaining oil,while the remaining oil may concentrate within the densely barriered area. |
