沥青调剖颗粒与大庆喇嘛甸油层配伍关系

Matching of asphalt particles and formation pores for conformance control treatment in Lamadian Oilfield of Daqing

大庆喇嘛甸油田经过长期注水冲刷进入高含水期,并且存在注入水无效循环、水窜现象严重等问题,须采取调剖封堵增产措施。沥青颗粒主要是通过封堵高渗透水窜通道和扩大波及体积提高采收率,但现场应用过程中存在注入压力过高的问题,须通过室内试验研究沥青颗粒与地层配伍关系。根据相似准则和近井地带分流效应,研制带测压点的特殊胶结岩心,通过综合分析注入沥青颗粒及后续水驱过程中的阻力系数、残余阻力系数及封堵率,给出沥青颗粒粒径与油层的配伍关系,确定浓度对注入性的影响。结果表明：渗透率为2μm2的地层与粒径为（0.1~0.3）mm沥青颗粒配伍适宜,粒径过大或过小都会限制扩大波及体积作用;沥青颗粒浓度会限制其运移能力,当浓度增加到5 g/L时沥青颗粒会在地层局部大量堆积,高浓度沥青颗粒段塞注入过程可采用与水交替注入方式。

The Lamadian block in Daqing Oilfield has been water flooded, and it is now at a high water cut stage with serious water channeling and ineffective water circulation. It is necessary to take channel blocking and conformance control meas- ures. Asphalt particles can be used to plug water channeling in high permeability zones in order to increase sweeping volume for improved oil recovery. In field applications, high injection pressure can be induced if the sizes of asphalt particles are not matched with formation pores in the reservoir. Experimental study was conducted using specially designed cement cores, based on similarity criteria to simulate the flow conditions in wellbore, to investigate the blocking effect of asphalt particles. The resistance coefficient, residual resistance factor and plugging rate were measured and analyzed to assess the matching between asphalt particles and the pores of the simulated cores, and the influence of particle concentration was also studied. The experimental results show that the cores with permeability 2 μm2 can be matched with the asphalt particle size of 0. 1-0. 3 mm. Undersized or oversized particles can reduce the conformance control effect, and the concentration of asphalt particles in the injectant can limit their migration ability. When the particle concentration is increased to 5 g/L, accumulations of asphalt particles can be caused in the formation, in which a scheme with asphalt particles alternative water injection is proposed to a- void the accumulation.