气湿对凝析气藏渗流特征的影响

Effects of Gas-Wetting on Porous Flow Behavior in Gas-Condensate Reservoirs

通过毛细管上升法、Washburn法和自发渗吸法实验,研究了十二烷基苯磺酸钠、十六烷基三甲基溴化铵、辛基苯酚聚氧乙烯醚OP-15、二甲基硅油GB-201、二氯二甲基硅烷等化学剂使人造砂岩岩心的润湿性向气湿转变的能力及特点;用非稳态渗流法实验研究了它们对气液两相渗流的影响,并测定岩心润湿性改变前后的气、液相对渗透率。实验结果说明:在气/水体系中,二甲基硅油和二甲基二氯硅烷可以将强水湿表面转变为优先气湿表面;在油/气体系中,二甲基硅油可以将强油湿表面转变为弱油湿或中性润湿表面;与亲油、亲水表面相比,优先气湿的孔隙表面液相流动性显著增强;润湿性由液湿转变为优先气湿后,液相相对渗透率增加,液相饱和度降低,等渗点左移,气相相对渗透率减小。通过这种润湿性反转处理可以改善井眼附近的渗流环境,提高凝析气藏的生产能力。

The capability of dodeeyl benzene sulfonate, cetyl trimethyl ammonium bromide, octylphenyl polyoxyethylene ether OP- 15, dimethyl silioone oil （DSO） GB-201, and dichloro dimethyl silane （DMS） to alternate artificial sandstone core surfaces to gaswetting ones is studied by using capillary tube, Washburn＇s, and imbibition methods through wetting angle determination; the gas and liquid flow behavior through the porous medium and the gas and liquid phase relative permeabilities are determined by using an unsteady flow state method before and after the wettability alternation. Following results are obtained. For a gas/water system, and DMS change the surfaces of porous medium from strongly water-wetting to preferentially gas-wettingl for a gas/oil system, DSO and DMS change the surfaces from strongly oil-wetting to weakly oil-wetting or neutral wetting; the liquid phase flowability is significantly improved in a porous medium with preferentially gas-wetting pore surfaces in comparison to oil- and water-wetting pore surfaces; the alternation of pore surfaces in the porous medium from liquid-wetting to preferentially gas-wetting leads to increase in liquid phase relative permeabilities, decrease in liquid saturation, left shift of iso-permeabiliw point, and reduction in gas phase relative permeabilities. This wettability alternation can be used as a way of improving the flow circumstances around wellholes and stimulate the gas-condensate reservoirs.