Study On Characteristic Of Horizontal Well Water Flooding In Sandstone Reservoir With Bottom Water Of Tahe Nineth Area

Share of reservoir with basal water in the reservoir is large, and reserve volume is rich. With thedevelopment of horizontal well technology, increasing number of horizontal well in such reservoirsis applied. Horizontal than vertical wells to develop the reservoir has more significant advantages,such as well drainage area increasing, filtrational resistance reducing. Thus it substantially increasesthe production of single well and reservoir recovery, and the recoverable reserves. Therefore studyof the water flooding becomes more important. Using water drive curve to study the characteristicsof the water flooding is a Common method to reservoir engineers. But theory of water drive curvesin practice is often not ideal, it need to analyze the actual situation of reservoir. Especially peopleresearched on it basing on reservoir developed by vertical well, and there is no specific research onhorizontal well water flooding.This paper focuses in Tahe ninth area，studies geological characteristics of sandstonereservoirs with bottom water，and analysis the structural characteristics, hydrocarbon bearing area,Sand and sandwich distribution, reservoir quality. Currently Triassic oil reservoir in the area has39developed wells in which34are opened. We analyze all single well production performance data.According to the daily oil production in the early production (than100T,100t-50T, less than50T),all producing wells are divided into three categories: high, middle and low yielding well; Accordingto whether there is water free oil production period, the water production type of wells is dividedinto three categories: more than100days, less than100days, and there is no water free oilproduction period; According to the actual water production of single well, the single well waterproduction type can be divided into4types from low to high water production. By analysis ofreservoir production performance, we recognize the current9th area’s composite water cut-71.7%,more than80%of wells’ water content closing to50%, and water content rising rapidly. In additionto analysis of production performance, according to the characteristics of water production ofhorizontal wells, all horizontal wells are divided into3types: water cresting type, complex type andincreasing water-saturation type. Through the above statistical analysis, we recognized the maininfluencing factors of water production of horizontal well: the height to the bottom water, structurallocation, fracture, intercalated bed, cumulative liquid production, permeability of horizontal section,oil production rate, core intersection and so on.We studied the water drive curves. By normalization method we got the relative permeability,water content ratio and water saturation of semi-logarithmic curve. Through the half-logarithmiccurve we recognized water drive curves may be line after the water content reaches17%. We usecharacteristics of single well water cut curve, combined with the first water drive curve to research characteristic of water drive. Based on characteristics of the two curves, all single well waterproduction patterns are divided into four types: unstable water flood, partial unstable water flood,partial stable and stable water flooding. By statistical analysis we could know that the bottom waterflooding of vertical well is more stable. Through the comparison of characteristics of water drivecurve between vertical wells and horizontal wells，we could know that four types of water drivecurve are applied to the vertical wells in this area, its manifestations are as same as study results ofwater drive curves by predecessors researched, but the2nd water drive curve cannot be applied tohorizontal well and combined with statistical analysis of water production patterns, know that a bigpart of the1st,3rd and4th type water drive curves are multi-segment distribution. Based on analysisof the theory, we get that this variance is mainly because of the difference of the water flood frontbetween vertical wells and horizontal wells. Therefore we apply the water flooding curves inthe reservoir developed by horizontal well, only when the water flood front reach the highest partof production section of the horizontal well. At this time water drive curves appear stable linearform, and only at this time we could use of water flooding curves to predict the water contentratio, recoverable reserves and so on.