Research On Displacement Pressure And Capacity Of Sealing Oil Of Fault Rock In Southern Block33-1of Qinhuangdao

On the basis of the investigation of a large number of domestic and foreign literatures, itis considered that lateral seal mechanism of fault is that there is differential permeabilitybetween fault zone and surrounding rock. Based on the geologic process of differentialpermeating caused by fault activity, fault seal type can be divided into juxtaposition seal andfault rock seal. The geological processes of fault rocks forming lateral seal includedesegregation mixing, diffusive mass transfer, cataclasis, cementation and clay smearing.Lateral seal ability of fault with the type of lithology juxtaposition seal can be evaluated byuse of Allan and Knipe graph. For fault with the type of fault rock seal, we can simulate thematerial composition in fault zone by calculating fault zone seal attribute value SGR, and thenestablish the relation between SGR and oil column height which sealed by it, namely lateralseal-failure envelope of fault. On basis of research about development and activity history ofmain reservoir-controlling fault in Qinhuangdao33-1S block and analysis of fault sealingmechanism and influence factors, by use of measured displacement pressure of puresandstone and mudstone in different depth, the displacement pressure-depth relation chart indifferent shale content was established by interpolation. According to the relation betweengeostatic pressure and buried depth of strata, the buried depth of strata which was equivalentto section pressure at breakpoint was calculated. Meanwhile according to the calculation ofshale content in fault zone, the displacement pressure was obtained by use of the chart.Similarly, displacement pressure of reservoir was calculated using shale content and burieddepth of reservoir equivalent to fault section. Seal ability was evaluated quantitatively by useof differential displacement pressure between reservoir displacement pressure anddisplacement pressure of fault rock in fault zone. The results show that in plane, there is agood correlation between the fault lateral seal ability and SGR value of fault rock,the higherSGR value of fault rock, the stronger the lateral sealing faults; conversely, the weaker. Invertical, the fault lateral seal ability and SGR value of fault rock,the higher SGR value offault rock, the stronger the lateral sealing faults; conversely, the weaker. And the evaluationresults obtained in the lateral control trap fault seal oil column height in the range of2.9-49.4m fault has seal capabilities. This evaluation result is basically tallies with oil fielddevelopment result, which proves that the evaluation method of fault sealing is feasible.