摘要
以四川盆地志留系龙马溪组和鄂尔多斯盆地三叠系延长组页岩为研究对象,从微观作用力的角度分析页岩水化机理,进行水合力的定量表征,并开展矿场应用。选取了与伊利石组成和性质都极为相似的白云母进行微观作用力测试。结果显示云母片在电解质溶液中的微观作用力主要包括DLVO(Derjaguin-Landau-Verwey-Overbeek)力和水合力。当电解质浓度较低时,测试曲线符合DLVO理论;但当电解质浓度大于临界值且云母片间距小于5 nm左右时,测试曲线完全偏离DLVO理论曲线,水合力开始占据主导作用。定量计算表明水合力强度随作用距离增加呈双指数型衰减。矿场应用表明,严格控制水相侵入并降低水合力强度是防塌钻井液体系设计的关键;压后焖井过程中充分利用页岩水化致微裂缝萌生、扩展可进一步改造页岩储集层。
Shales（illite was the dominant clay mineral） of Silurian Longmaxi Formation in Sichuan Basin and Triassic Yanchang Formation in Ordos Basin were taken as subjects to examine the mechanisms of shale-water interaction, quantitative characterization of hydration force and potential field applications based on micro forces analyses. Mica sheet with composition and property very similar to illite was tested for micro forces between the crystal layers. In electrolyte solution, micro forces between mica-solution-mica system include DLVO（Derjaguin-Landau-Verwey-Overbeek） force and hydration force; when the electrolyte concentration was low, the tested curve agreed with the theoretical DLVO curve; when the electrolyte concentration was higher than the critical value and the distance between mica sheets was less than 5 nm, the tested curve deviated from the DLVO curve completely, and the hydration force became dominant. Quantitative analysis indicated that the hydration force decayed in a rapid double-exponential type with the growth of distance. Field applications indicate that strict control of water invasion and reducing the strength of hydration force are the keys in designing collapse-preventing drilling fluids; meanwhile, during the shut-in period of shale gas wells, shale-water interaction can induce and extend micro-cracks, further improving the stimulation effect of shale reservoirs.
作者
康毅力
杨斌
李相臣
杨建
游利军
陈强
KANG Yili YANG Bin LI Xiangchen YANG Jian YOU Lijun CHEN Qiang(State Key Laboratory of Oil ＆ Gas Reservoir Geology and Exploitation in Southwest Petroleum University, Chengdu 610500, China Engineering Technology Research Institute of CNPC Southwest Oil ＆ Gas Field Company, Guanghan 618300, China)
出处
《石油勘探与开发》
SCIE
EI
CAS
CSCD
北大核心
2017年第2期301-308,共8页
Petroleum Exploration and Development
基金
国家科技重大专项"彭水地区常压页岩气勘探开发示范工程"(2016ZX05061)
国家自然科学基金(51674209)
国家重点基础研究发展计划(973)项目(2013CB228003)
关键词
页岩
水化作用
水合力
伊利石
井壁失稳
焖井
hydration
hydration force
illite
wellbore collapse
well shut-in
