钙芒硝吸水重结晶对盐间油藏的影响分析

Analysis of the Effects of Water-absorbing and Recrystallization of Glauberite on Intra-salt Reservoir

盐间油藏结盐严重,影响了后期生产和措施效果。为了弄清储层矿物的结盐机理,室内开展了物模试验。研究表明:盐间油藏成藏过程中,水不断排出经过钙芒硝矿物时,在高温高压条件下作用形成多水结晶体,堵塞水相渗流通道,表观反应储层封闭性好,孔隙不连通性;开采过程中,措施会对上下盐膏层造成干扰而发生蠕动、变形,水基措施液溶盐后,在流向井筒过程中,加上温度、压力变化,在近井筒附近形成结晶,影响油井的正常生产。

The severe salt-deposition in intra-salt reservoir has great influence on the production and stimulation effects at later development stage. In order to study the salt deposition mechanism of the reservoir minerals, physical-modeling experiments have been conducted indoors. The study results demonstrated that during the formation of intra-salt reservoir, water had been discharged continuously. When water passed the glauberite mineral, water-rich crystalline substances formed under high temperatures and high pressures, which obstruct the infiltration flow channels, resulting in the high closure property of the reservoir and disconnectedness of pore holes. During the oil production, the upper and lower salt formations can be interfered during stimulations, wriggle and deformation might occur. After the water-based stimulation fluids dissolve the salt and flow toward the wellbore, crystalline substances formed near wellbore due to thermal and piezometrical changes, which might influence the regular production in oil wells.