Study on the developing method of sequestration reserve after chemical flooding in class Ⅱ oil reservoirs in Daqing Oilfield
Series of strata in class Ⅱ reservoir of Daqing Oilfield are divided into 3～6 sets.The chemical flooding of the first set of layers in some blocks is completed,and the second set of layers start chemical flooding,resulting the reserve of the first set of layers is sealed.In order to determine the developing method of sequestration reserve after chemical flooding in class Ⅱ reservoir,taking B1D East block as an example,we use the virtual well pattern design and the break-even principle to study injection-production well spacing and thickness limit of layers combination after chemical flooding,determining that using old wells releases sequestration reserve and the reasonable well spacing is 200～250 m.Three well pattern adjustment schemes were compared and optimized to determine sequestration reserve is released using secondary infill well.Staged perforation is used to exploit all oil layers from Sa Ⅱ 10 to Sa Ⅲ 10 and Sa Ⅰ and Pu Ⅱ oil layers with original perforation of the secondary infill well pattern.Numerical simulation is used to study the releasing time of sequestration reserve,the earlier the perforation adding time is,the higher the ultimate recovery factor is.Using the break-even principle to study economic limit water cut,the higher the liquid production and oil price are,the higher the economic limit water cut is;the earlier the perforation adding time of secondary infill well is,the higher the economic limit water cut is.Perforation adding is done under current water cut,the economic limit water cut can reach 98.7％.6 wells were tested in B1D East Block,average daily liquid rate increased by 29.3 t per well,daily oil rate increased by 1.25 t,and water cut decreased by 1.0 percentage point.Test wells have been popularized and applied in 4 blocks of Daqing Oilfield.545 wells added perforation,average daily oil rate increased by 1.0 t per well,water cut decreased by 0.7 percentage point,which achieves good results and has broad application prospects.
Daqing Oilfieldclass Ⅱ reservoirafter chemical floodingsequestration reservewell pattern adjustmentadjustment time
万方数据
维普
