阿南砂岩油藏注水开发中后期水淹特征

为揭示注水开发中后期油藏水淹状况及潜力分布 ,探索合理的开发技术政策 ,运用毗邻的开发早期系统油基泥浆取心井与注水开发中后期的密闭取心井的分析化验及动态等资料 ,研究了阿南低渗透砂岩油藏的纵向及层内水淹特征、水淹层的物性变化及孔隙结构特征的变化 ,探讨了油层水淹后对开发的影响。分析认为 ,阿南低渗透砂岩油藏相对高渗层 ,既是油藏的主力层 ,也是油层污染和水淹的主要对象 ,油层水淹的结果 ,导致喉道分异加剧 ,粗喉更粗 ,细喉更细 ,使油层主要流动喉道控制的有效孔隙体积减少 ,无水采油期缩短 ,最终驱油效率降低 ,这是目前油田注水开发含水高、含水上升快 ,产油量低 ,油田不能通过提液提高产量的根本原因。细分开发层系 ,是提高这类厚层砂岩油藏驱油效率的有效途径

Water flooding out characteristics of Anan sandstone oil reservoir at its medium-later development stage

Vertical and intra layer water flooding out cha racteristics, the change of petrophysical properties and the change of porous structures after flooding out are studied by a combination of data from oil base mud core analysis at ear ly development stage in a neighboring area, uncontaminated core analysis from wa ter injection wells at middle late development stage and reservoir behavior dat a to reveal the matter of water flooding out and the distribution of further po tential of production in the oil reservoir to find a reasonable development poli cy and to deal with the effects on the reservoir beds after water flooding out. Results show that relatively high permeability part of the Anan low permeabil ity oil reservoir is the main productive layer and is the mainly damaged and flo oded out one also. Results of flooding out lead the strong differentiation of pore and throats: large throats become larger; and small ones become smaller. T hus effective pore volume in the main flooding path controlled by those pores be comes lesser to give a relative short period of water free period and a lower u ltimate recovery. This is the main reason why water production is high and produ ction rate is low and the water out rises rapidly; and these cannot be correcte d by increase the total liquid production rate. Detailed layer separation will b e the effective way to increase the efficiency of oil displacement in the develo pment of such thick sandstone oil reservoirs.