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1、鄂爾多斯盆地姬塬地區(qū)長8致密儲層溶蝕作用模擬及其影響因素摘要:在明確鄂爾多斯盆地姬塬地區(qū)西部長8致密儲層基本特點的基礎(chǔ)上,利用高溫高壓儲層流體巖石相互作用模擬儀,模擬了長8儲層巖石與有機酸溶蝕反應的過程。依據(jù)地質(zhì)條件,采用015mol?L-1乙酸溶液(pH=2.65)作?櫸從θ芤海?模擬溫度選溶蝕窗口對應深度的實際古地溫(87℃~103℃),模擬壓力范圍為24.70~30.18MPa。通過反應前后樣品儲層特征的變化及溶蝕率對比,分析了長8致密儲層的溶蝕特征及影響因素,探討了其溶蝕過程及溶蝕增孔過程。結(jié)果表明:在乙酸的作用下,致密儲層長石(鈉長石、鉀
2、長石)和方解石礦物發(fā)生明顯的溶蝕反應,并產(chǎn)生沉淀物;根據(jù)礦物相對溶蝕率發(fā)現(xiàn),碳酸鹽礦物的溶解速率整體上大于長石礦物,其中方解石大于白云石,斜長石大于鉀長石;隨著溫度和壓力的增加,方解石溶蝕率先增加后不變,而長石溶蝕率基本呈線性增加,但是方解石剛開始溶蝕率高于長石;致密儲層溶蝕過程主要分為3個階段,分別為方解石膠結(jié)物溶蝕過程、長石溶蝕過程和溶蝕后沉淀物充填過程。溶蝕作用使得致密儲層的孔隙明顯增加,是致密儲層增孔的主要成巖作用類型,也是尋找致密儲層中“甜點”的關(guān)鍵因素之一。中國8/vie 關(guān)鍵詞:致密儲層;溶蝕礦物;模擬試驗;流體巖石相互作用;X射線
3、衍射;溶蝕率;延長組;鄂爾多斯盆地 中圖分類號:P618.130.2文獻標志碼:A DissolutionSimulationofChang8TightReservoirinJiyuanAreaofOrdosBasin,ChinaandItsInfluencingFactors OUResourcesofGansuProvince/KeyLaboratory ofPetroleumResourcesResearchofChineseAcademyofSciences,Lanzhou730000,Gansu,China; 3.Univers
4、ityofChineseAcademyofSciences,Beijing100049,China;4.StateKeyLaboratoryof PetroleumResourcesandProspecting,ChinaUniversityofPetroleum,Beijing102249,China) Abstract:BasedonthestudyofthebasicfeaturesofChang8tightreservoirinulatedbythefluidrockinteractionsimulatorofhightemperatu
5、reandpressurereservoir.Accordingtothegeologicalconditions,015mol?L-1aceticacidsolutionulatedtemperatureperature(87℃103℃)correspondingulatedpressureplesbeforeandafterthereactionentineralsoccursobviously,andproducessediments;accordingtotherelativedissolutionrateofminerals,thedis
6、solutionvelocityofmineralislargerthanthatoffeldsparinite,andthatofplagioclaseislargerthanpotassiumfeldspar;peratureandpressure,thedissolutionratesofcalcitesremainunchangedafterthefirstincrease,andthedissolutionratesoffeldsparincreaselinearly,butthedissolutionratesofcalciteareh
7、igherthanthatoffeldsparsatthebeginning;thedissolutionprocessoftightreservoirisdividedintothreestages,includingcalcitecementdissolutionprocess,feldspardissolutionprocessandsedimentfillingprocessafterdissolution.Dissolutionmakestheporesoftightreservoirsincreasingsignificantly,an
8、disamaindiageictypeoftightreservoirporosityenhancement,andisa