巴彦油田疏松砂岩储层保护技术

Study on Technology for Protecting Loose Sandstone Reservoir in Bayan Oilfield

巴彦油田储层属于中孔、中低渗为主的深部弱胶结砂岩储层,储层水敏性强,在用钻井液为淡水体系,抑制能力差,易引起地层水矿化度变化,导致储层污染。中国具有同样埋藏深度同时又具有类似储层物性特点的油田很少,需要针对疏松砂岩储层特点研发一种新型微米储层保护剂。在分析巴彦油田储层伤害因素的基础上,自主研发了一种兼具成膜与防膨效果的微米乳液储层保护剂,通过激光粒度分析、砂床封堵、PPA封堵滤失、扫描电镜等评价方法,验证了微米暂堵剂的广谱封堵和协同增效效果。该产品粒径D50≤2.17μm,D90≤7.05μm,线性膨胀降低率达到51.35%,与钻井液体系配伍性良好,与可酸溶材料配伍形成了一体化广谱封堵技术。室内实验表明,该广谱封堵技术针对弱胶结砂岩储层岩心渗透率恢复值可保持在90%以上。现场试验中,通过表皮系数测试和试油投产数据等综合对比表明,该广谱封堵技术具有良好的储层保护效果。

The reservoirs in the Bayan oilfield are weakly cemented sandstone reservoirs with medium and low permeability.Those reservoir formations are buried deep and are strongly water sensitive.Fresh water based drilling fluids have long been used to drill the wells,and because of the poor inhibitive capacity of the drilling fluids,the reservoirs are contaminated by the change in the salinity of the formation waters.Oilfields with the same buried depth and the similar reservoir physical properties in China are rarely seen,and a new micrometer sized reservoir protection additive is needed for drilling the loose sandstone reservoirs.Based on the analyses of the factors related to the reservoir damage in the Bayan oilfield,a micrometer sized emulsion reservoir protection agent with both filming and clay swelling inhibitive capacity was developed.The capacity of the reservoir protection agent to plug fractures with wide size distribution and the synergistic effect of the reservoir protection agent is verified using laser particle size analyzer,sand-bed plugging tester,PPA plugging filtration tester and SEM.The particle size of the reservoir protection agent D50 is≤2.17μm,and the D90 is≤7.05μm.The percent reduction of the linear swelling of cores tested with the reservoir protection agent is 51.35%.Compatibility of the reservoir protection agent with the drilling fluids in which it is used is satisfactory.The reservoir protection agent,combined with acid soluble materials,forms an integrated reservoir protection fluid capable of protecting reservoirs with various properties.Laboratory experimental results show that using this technology,percent permeability recovery of cores made with rock samples from weakly cemented reservoir sandstones can be 90%or higher.In field supplication,skin factor measurement and well production data all demonstrate the good reservoir protection capacity of this technology.