Study On Residual Oil And Potential Tapping Of RB Carbonate Reservoir On The Late Stage Of Development

RB reservoir is a layered carbonate reservoir with edge water.The natural energy is poor and the geologic setting is complicated.RB reservoir is on the late stage of high water-cut development now.Due to high stratigraphic dip,massive fractures and strong reservoir heterogeneity,the connectivity is complex which leads to the problem between injection and production.Although different ways of water injection is tried,the reservoir is flooded seriously.In this situation,it is necessary to make a study on residual oil distribution on the basis of fault closed function and water driving characteristics.Then according to different types or patterns of residual oil,choose potential area and take effective measures to ensure the reservoir development sustained and stable.Facing to existing problems of reservoir development,this study,based on deepening the basic geological study,is mainly to find out the factors of controlling the remaining oil distribution on the late stage of high water-cut idevelopment and find out the characteristics of reservoir water flooding and residual oil distribution by numerical simulation,production practice,dynamics and static analysis.Then make sure the features of residual oil distribution.At last,based on the above research results,evaluate the measures and effectiveness of reservoir comprehensive control and make a reasonable technical measures and developing methods indicating the direction for reservoir management work in the next step.Comprehensive geological study and field exploration research shows that the structure and the low permeability are the main factors to control the residual oil distribution on the late stage of high water-cut development.Especially,thick and stable impervious beds with closed faults are good for residual oil accumulating.The residual oil are vertically distributed in the high structural area and wide spacing area,while the residual oil are horizontally distributed in relative low permeable formation(such as 02L1-3 and 02X2-3 layers,etc.)and denudation edge of ∈f formation.Choose 9 potential areas to indicate the direction for reservoir management work in the next step.According to the characteristics of the residual oil distribution and development condition,stimulated measures on drilled well technology,adjustment wells drilling technology,shut-in well recovery technology and so on.In terms of measure ways,mud plugging,acidizing,water plugging and increasing production are still the main measures on the late stage of high water-cut development.These main measures have the same mechanism of increasing oil that is controlling the product capacity of larger fractures and vugs to exploit the small fracture or microfracture with high oil saturation by pressure difference.Comparing all kinds of measures and effects,each has advantages and disadvantages.Mud plugging makes higher average single well oil production and cumulateive incremental oil production,Acidizing and increasing production are high effective rate.Water plugging are used more,but scattered residual oil and complicate oil-water relation make the measure technology more difficult and shorten the period of validity.Choose 11 wells of 3 different types of stimulated measures and make 4 new wells,which can increase oil production of 1.59×104t.In this way,the reservoir decline will slow down and the effect of reservoir development will be improved.