【摘要】：本文通過流變測量、DSC方法研究了兩種長慶含蠟原油基本物性和流變特性,對含蠟原油粘彈性結(jié)構(gòu)的形成及屈服破壞過程特性進(jìn)行了詳細(xì)的分析和探討,并基于損傷變量理論,建立了能夠描述恒定應(yīng)力和連續(xù)增加應(yīng)力條件下粘彈性結(jié)構(gòu)屈服破壞全過程的蠕變模型。本文主要研究內(nèi)容如下:(1)兩種長慶油樣均為典型含蠟原油,膠質(zhì)、瀝青質(zhì)含量不高(分別小于1.3%和0.027%),密度較小(均小于0.84g/cm3),蠟含量高(均大于11%),凝點(diǎn)較高(50℃熱處理溫度下分別為24℃和17℃),且凝點(diǎn)隨熱處理溫度升高而顯著降低,常溫下流動(dòng)性較好。(2)研究了降溫速率、剪切應(yīng)力和重復(fù)加熱對降溫過程中長慶含蠟原油粘彈性結(jié)構(gòu)形成過程的影響,發(fā)現(xiàn)降溫速率越小、剪切應(yīng)力越小、重復(fù)加熱溫度越高,原油開始膠凝的溫度越高,同時(shí)相同溫度下形成的結(jié)構(gòu)越強(qiáng)。利用流變學(xué)原理分析計(jì)算驗(yàn)證了原油中蠟晶溶劑化層的存在,并結(jié)合結(jié)晶學(xué)原理,蠟晶溶劑化層的存在使得原油中的內(nèi)相濃度增大,更多液態(tài)油包裹其中,導(dǎo)致體系粘度增大。(3)研究了不同的應(yīng)力加載方式對長慶含蠟原油粘彈性結(jié)構(gòu)屈服破壞過程的影響,發(fā)現(xiàn)膠凝含蠟原油在恒應(yīng)力下的屈服是一個(gè)蠕變過程,應(yīng)力越大,屈服時(shí)間越短,當(dāng)應(yīng)力小于臨界屈服應(yīng)力時(shí),結(jié)構(gòu)不會(huì)屈服。在連續(xù)增加剪切應(yīng)力條件下,加載速率越大,屈服時(shí)間越短,屈服時(shí)應(yīng)力越大。剪切應(yīng)力和作用時(shí)間是導(dǎo)致粘彈性結(jié)構(gòu)屈服的兩個(gè)關(guān)鍵因素,較大應(yīng)力在較短時(shí)間使結(jié)構(gòu)屈服,較小應(yīng)力則需要較長的時(shí)間使結(jié)構(gòu)屈服。(4)針對膠凝含蠟原油蠕變的階段性特征,引入損傷變量,將時(shí)間和應(yīng)力作為應(yīng)變的變量,建立了含蠟原油粘彈性蠕變模型,即建立?(t,?)函數(shù),結(jié)果表明預(yù)測值和實(shí)驗(yàn)值相吻合,該模型可以準(zhǔn)確描述含蠟原油屈服破壞過程。在已建立的膠凝含蠟原油非線性蠕變模型的基礎(chǔ)上建立了剪切應(yīng)力連續(xù)增加條件下的應(yīng)變-時(shí)間-應(yīng)力變化速率模型,即建立?(t,?)函數(shù),結(jié)果表明該模型誤差小,可以較好描述應(yīng)力連續(xù)增加條件下粘彈性結(jié)構(gòu)的屈服過程。該模型在含蠟原油領(lǐng)域有較好的應(yīng)用前景。
[Abstract]:In this paper, the basic physical properties and Rheological properties of two kinds of waxy crude oil in Changqing have been studied by means of Rheological measurement and DSC method. The formation of Viscoelastic structure and the characteristics of yield failure process of waxy crude oil have been analyzed and discussed in detail, and based on the damage variable theory, A creep model which can describe the whole process of yield failure of Viscoelastic structures under the condition of constant stress and continuous increasing stress is established. The main contents of this paper are as follows: (1) the two kinds of Changqing oil samples are typical waxy crude oil, colloid, asphaltene content is not high (less than 1.3% and 0.027%, respectively), the density is small (both less than 0.84g/cm3), The wax content is high (all > 11%), the freezing point is higher (24 鈩，

本文編號：2486898