坨11区块泡沫驱油的室内研究与现场实践

Foam Flood to Enhance Oil Recovery in Block Tuo-11: Laboratory Study and Field Practice

胜利油田坨11区块稠油油藏水驱开发已进入高含水期.油藏地温～60℃,平均渗透率～1.5 μm2,地层水矿化度12.4 g/L,含Ca2++M2+580 mg/L.筛选出了发泡剂DP-4,其5 g/L溶液形成的氮气泡沫表现粘度μa=789.5 mPa·s,阻力系数FR=1579,残余阻力系数FRR=186,加入聚合物HPAM(0.5～2.5 g/L)对μa和FR影响不大,但使FRR急剧增至488.5～737.0.气液比为1:1和2:1时聚合物复合氮气泡沫的FR均在1500以上,表明该泡沫体系有强封堵能力;FR随渗透率增大(0.7～10μm2)由1100增至4200,表明该泡沫体系的封堵具有渗透率选择性.在油饱和人造岩心上,在水驱之后注入DP-4/HPAM氮气泡沫使采收率由54%提高至79%.在坨11北区1口油井注入DP-4/HPAM(10～5/2.0～1.8 g/L)氮气泡沫,气液比1:1,共注入地面氮气6.044×105m3,DP-434.75 t,HPAM 1.1t,周围4口同层位油井平均含水由71.5%降至44.7%,15个月增产油12072 t,减产水6445m3,且仍处于增产有效期.图4表2参2.

In high water cut stages of their development by water flood, the heavy oil reservoirs of Block Tuo-11, Shengli are characterized by temperature -60℃, average permeability - 1.5μm^2, TSD = 12.4 g/L and Ca^2＋ ＋ Mg^2＋ content 580 mg/L in formation water. DP-4 is chosen as foaming agent （FA）. 5 g/L FA solution forms with nitrogen foam of apparent viscosity μa= 789.5 mPa·s, resistance factor FR = 1579 and residual resistance factor FRR = 186 and introducing polymer HPAM at dosage 0.5- 2.5 g/L affects μa, and FR of the foam slightly and FRR notably, the latter is increased to 488.5-737.0. The FR value of FA/ polymer N2 foam at gas-to-solution ratio （GSR） 1：1 and 2：1 is 〉1500, showing strong sealing/plugging capacity of the foam, and increases from 1100 to 4200 with permeability increasing from 0.7 to 10μm^2, which states permeability selectivity of the foam in sealing/plugging. On oil saturated artificial cores, injecting FA/polymer N2 foam after water flood finished increases oil recovery from 54% for water flood to 79%. In northern district of Block Tuo-11, FA/olymer （10-5/2.0-1.8 g/L） foaming solution and N2 at GSR= 1：1 are injected into a production well in total amount of 6.044 × 10^5 m^3 N2 at surface, 34.75 t FA, and 1.1 t polymer and in result the average water cut in 4 surrounding wells with the same pay layer is decreased from 71.5% to 44.7%, an increment of oil output of 12072 t and a decrement of water production of 6445 m^3 in these wells are observed in successive 15 months and the positive response to the foam flood continues here after.