天然沸石在聚合物驱中的调剖效果及调驱段塞结构实验研究

Experimental Studies on Profiling/Flooding Efficiency and Slug Structure with Natural Zeolite Profile Modificator in Polymer Flooding

聚合物溶液沿高渗透层突进,是影响大庆油田聚合物驱效果的一个主要因素.为此,在人造岩心上考察了沸石调剖剂在聚合物驱中的调驱效果和注入工艺.实验岩心包含厚0.9、1.8、18 cm,有效渗透率分别为6.0、1.2、0.3μm2的3个层段;实验聚合物分子量2.5×107,聚合物溶液浓度1000 mg/L,45℃、7.35 s-1粘度35.4 mPa·s;沸石细度大于200目,以500mg/L聚合物溶液为携带液,其浓度为20 g/L,粘度～8.5 mPa·s.在沸石调剖剂(Z)+聚合物(P)调驱实验(45℃)中,取段塞总量为0.64 PV,不同段塞结构下的调驱采收率增值(以水驱后聚驱采收率25.1%为基准)如下:当Z+P段塞中Z段塞尺寸由0.05 PV增至0.15 PV时,采收率增值由0.6%增至3.8%;当P1+Z(0.1 PV)+P2段塞中P1段塞尺寸由0.1 PV增至0.49 PV时,采收率增值由2.3%降至0.9%;P(0.1 PV)+Z(0.1 PV)+P(0.44 PV)是较好的调驱段塞结构,采收率增值为2.3%;将其中Z段塞浓度提高至40 g/L可使采收率增值达到4.5%.电镜照片显示天然沸石颗粒外形不规则,表面吸附聚合物后容易在岩石孔隙中发生桥堵而造成封堵效果.图2表1参8.

The hurtlement of polymer solution along high perrneable zones in reservoir strata is an important factor affecting the oil displacement efficiency in polymer flood in Daqing. The profiling/flooding efficiency and the injection technology of zeolite profile modificator （ZPM） in polymer flood are investigated on artificial cores, which contain 3 layers 0.9, 1.8, and 1.8 cm thick and of effective permeability 6.0, 1.2 and 0.3 μm^2 1, respectively. A polymer of M^- = 2.5 × 10^7 and 1000 mg/L polymer flooding solution （PFS） with viscosity at 45℃ and 7.5 s^- 1 are used. The zeolite of particle size 〉200 mesh is dispersed in 500 mg/L polymer solution thus forming a 20 g/L zeolite suspension of viscosity -8.5 mPa·s used as ZPM. In core profiling/flooding experiments at 45℃ with 0.64 PV of ZPM ＋ PFS injected totally after water flooding finished, the enhancement in oil recovery （EiOR） over that by plain polymer flood, 25.1%, varies with change in slug structure in such a way that EiOR increases from 0.6 % to 3.8 % when the size of ZPM slug in ZMP＋ PFS increased from 0.05 PV to 0.15 PV and decreased from 2.3% to 0.9% when the size of foregoing PFS slug in PFS＋ ZPM （0.1 PV） ＋ PFS increased from 0.1 PV to 0.49 PV; slug structure PFS＋ ZPM＋ PFS （0.1 ＋ 0.1 ＋ 0.44 PV） is shown to be a proper one, with which an EiOR of 2.3% is observed, and EiOR can be increased to 4.5% when more concentrated （40 g/L） ZPM is used. SEM photographs demostrate irregular contour of natural zeolite particles, the laters with polymer adsorbed on surfaces readily create bridging and filling in rock pores and make them plugged.