致密油藏注水诱导裂缝试验规律

打开文本图片集

中图分类号：TE348 文献标志码：A

Abstract：Thegenerationand expansionoffractures inducedbywaterinjection intightoilreservoirscan intensifythecontradictionbetweenijectionandproduction，educingtheaffectedvlumeofwaterflooding，andafecttherecoveryfactorof the oilfields.Inthisstudy，anexperimentaldevice wasdesignedandmanufacturedtosimulate waterinjectioninducedfractures intightoilreservoirsinorder investigatethemechanismandtheirexpansionof waterinjectioninducedfractures.Oil-water distributionandoildisplacementeficiencyunderdiferent fracturesizeswerestudiedthrough fulldiametercoredisplacement experiments.Theexperimentalresultsshowthatthesmalerthe water injection displacement，theeasierforasingle nduced fractureorcacktobeformed，whilethelargerthewaterinjection，causinggreaterfracturepressure，largerfractaldimesion andcrack width，andtheeasier forcomplexcracks tobegenerated.The injection displacement ispositivelycorelated with thedevelopmentoftheinducedcracks.Thedeeperthedrilingdepth，thelowertheinducedcrack initiationposition，and themorelikelyforacomplex network with crossing through cracks tobeformed.The expansionand extensionof thecracks are greatlyaffctedbygeo-stressandheterogeneity，ndthecracks extendordeflectalong thedirectionof maximumpricipal stressThe depth，angle，andcomplexityofthe induced fractures havea significant impactonoil displacement efficiency， whiletheefectsof theoriginalporosityandpermeabilityofthereservoirarerelativelyreduced.Thelargertheanglebetween fracturesandtheverticalwelboredirection，thegreaterthefractaldimension，andthegreaterthedepthoffractures，thelower the oil displacement efficiency.

Keywords：tightoilreservoir；water injection induced fracture；injection displacement；fracturing pressre；full-diameter core；oil displacement efficiency

致密油藏孔喉细小，非均质性强，注入水易沿裂缝发生突进，注水开发面临“裂缝易水窜，基质驱不动”的现象，油田水驱采收率低[1-5]。（剩余12963字）