【正文】
鉆速度:起鉆時(shí),鉆具底部產(chǎn)生負(fù)壓,使井底壓力減少。當(dāng)下鉆速度過(guò)快時(shí),同樣會(huì)引起過(guò)大的激動(dòng)壓力,造成井漏,影響井眼安全。(2)波動(dòng)壓力對(duì)鉆井安全的影響 由于鉆井液具有一定的粘度和切力,當(dāng)快速提升鉆柱(尤其是出現(xiàn)縮徑、鉆頭泥包)時(shí),都將引起過(guò)大的抽吸壓力。激動(dòng)壓力是指當(dāng)鉆柱向下運(yùn)動(dòng)時(shí),井內(nèi)鉆井液向上流動(dòng),使井底壓力增加,由此而增加的壓力值稱(chēng)為激動(dòng)壓力。4波動(dòng)壓力(1)波動(dòng)壓力的定義 由于井內(nèi)鉆具或流體上下運(yùn)動(dòng)而引起井底壓力增加或減少的壓力值。極限試驗(yàn)壓力要根據(jù)下部地層鉆井將采用的最大鉆井液密度及溢流發(fā)生后關(guān)井和壓井時(shí),對(duì)該地層承壓能力的要求決定。當(dāng)套管鞋以下第一層為脆性巖層時(shí),只對(duì)其做極限壓力試驗(yàn),而不做破裂壓力試驗(yàn)。曲線中偏離直線之點(diǎn)的壓力PL則為漏失壓力;計(jì)算破裂壓力當(dāng)量密度(ρf): ρf =ρm試+PL/ (28)式中 ρf——破裂壓力當(dāng)量密度,g/cm3; ρm試——試驗(yàn)所用鉆井液密度,s/cm3; PL——地層漏失時(shí)的井口壓力,MPa; Hf——裸眼段中點(diǎn)井深,m?! 〉貙悠屏褖毫υ囼?yàn)的工作程序: (1)試驗(yàn)前安全準(zhǔn)備:當(dāng)鉆至套管鞋以下第一層砂巖時(shí),用水泥車(chē)或柱塞泵進(jìn)行試驗(yàn),而裸眼長(zhǎng)短根據(jù)砂巖層的厚度決定;試驗(yàn)前應(yīng)處理好鉆井液性能(尤其是ρm試),保證試驗(yàn)時(shí)鉆井液性能均勻、穩(wěn)定;將上提鉆頭至套管鞋內(nèi)?! 〉貙悠屏褖毫μ荻菺f計(jì)算公式: Gf=Pf/Hf= (27)式中 Gf——地層破裂壓力梯度,MPa/m。所以,上部地層(套管鞋處)的強(qiáng)度最低,易于壓漏,最不安全。從鉆井安全方面講,地層破裂壓力越大越好,地層抗破裂強(qiáng)度就越大,越不容易被壓漏,鉆井越安全。3地層破裂壓力Pf 地層破裂壓力是指某一深度處地層抵抗水力壓裂的能力?! 〉貙訅毫μ荻菺p計(jì)算公式: Gp=Pp/Hp= (24)式中 Gp——靜液壓力梯度,MPa/m。2地層壓力Pp地層壓力是指作用在地層孔隙中流體上的壓力,也稱(chēng)地層孔隙壓力?! §o液壓力梯度Gm計(jì)算公式: Gm=Pm/Hm= (22)式中 Gm——靜液壓力梯度,MPa/m。在鉆井中鉆井液環(huán)空上返速度較低,動(dòng)壓力可忽略不計(jì),而按靜液壓力計(jì)算鉆井液環(huán)空液柱壓力?! ?3)早處理:在準(zhǔn)確錄取溢流數(shù)據(jù)和填寫(xiě)壓井施工單后,就應(yīng)進(jìn)行節(jié)流循環(huán)排出溢流和壓井作業(yè)。這是安全、順利關(guān)井的前提?! ?(1)早發(fā)現(xiàn):溢流被發(fā)現(xiàn)的越早越好、越便于關(guān)井控制、越安全?! ?3)三級(jí)井控:井噴失控后,重新恢復(fù)對(duì)井口控制的井控技術(shù)。(1)一級(jí)井控:指以合理的鉆井液密度、合理的鉆井技術(shù)措施,采用近平衡壓力鉆井技術(shù)安全鉆開(kāi)油氣層的井控技術(shù)(又稱(chēng)主井控)。2溢流(Over flow):當(dāng)井底壓力小于地層壓力時(shí),井口返出的鉆井液量大于泵入量,停泵后井筒流體從井口自動(dòng)外溢流出井口的現(xiàn)象。也就是說(shuō):井控技術(shù)是實(shí)施近平衡鉆井乃至欠平衡鉆井的關(guān)鍵與保障。為了對(duì)付復(fù)雜地層,安全優(yōu)質(zhì)地實(shí)施快速鉆井,必須把井控技術(shù)作為研究和發(fā)展的重要內(nèi)容。34第1章 概 述隨著油氣勘探開(kāi)發(fā)領(lǐng)域的不斷延伸擴(kuò)大,從陸上到灘涂淺海、從淺層到深層,鉆井難度越來(lái)越大,對(duì)井控技術(shù)和鉆井人員的要求越來(lái)越高。30結(jié)論29 井內(nèi)氣液混合物的密度24第5章 溢流關(guān)井的水擊及其控制22 起鉆時(shí)氣體運(yùn)移距離、速度和井口壓力15第4章 新的壓井技術(shù)與計(jì)算15 2第3章 井控技術(shù)與壓井方法2 character line method 。Based on the correct water hammer mathematic model,applying character line method,to translate the differential equation group into character equation group,to count the character equation integral along with character line and at the same time to substitute the integral form for the difference form SO as to make use of puter to carry through numerical value calculation of the water hammer pressure.The out put are as follows:1)“hard” shutin、“half soft” shut—in and “soft” shut in, the water hammer pressure decrease gradually;2)the top of a well、the casing shoe and the bottom of a well the water hammer decrease gradually because of dissipation;3)the gas call monish the water hammer pressure.Then the last calculative part of paper use ADINA software t o solve mathematical model.The whole result show that the output of ADINA software is consistent to that of theoretical mathematical model+Finally, considering the measure about controlling the water hammer ,the paperbining the other engineering,fearlessly apply the atmosphere jar to the well head assembly.Then the theoretic calculation show that the atmosphere jar can decrease the water hammer pressure.However, the well head assembly is too plex,whether this measure being appropriate need to be more considered.key words:water hammer pressure。特征線法。關(guān)鍵詞:水擊壓力。理論計(jì)算表明,空氣罐能有效的減小水擊壓力。 最后,對(duì)控制水擊的措施進(jìn)行了探索。同時(shí),為了進(jìn)行對(duì)比分析,本文采用了現(xiàn)今最為流行的有限元法,即通用軟件ADINA進(jìn)行水擊壓力的計(jì)算。同時(shí),應(yīng)用特征線法的原理.將數(shù)學(xué)模型的微分方程組轉(zhuǎn)化成特征方程組,沿特征線對(duì)特征方程進(jìn)行積分,并以差分方程形式代替積分形式對(duì)其求解。隨著顆粒含量的增加,水擊波速隨之上升;而氣體含量與此相反,氣體越多,水擊波速將會(huì)越小。 首先,本文簡(jiǎn)要介紹了當(dāng)前水擊計(jì)算的基本理論,包括水擊數(shù)學(xué)模型及其求解方法,指出了當(dāng)前水擊數(shù)學(xué)模型中存在的不足。最后在理論分析與實(shí)例計(jì)算的基礎(chǔ)上,首次提出在井口裝置上安裝空氣罐來(lái)減小水擊壓力的嘗試。摘 要 當(dāng)井內(nèi)發(fā)生溢流,應(yīng)立即關(guān)井,關(guān)井方式的合理選擇必須考慮關(guān)井水擊效應(yīng),以避免水擊壓力對(duì)裸露地層和井口裝置造成的破壞。本文在分析影響水擊因素的基礎(chǔ)上,建立了水擊效應(yīng)的數(shù)學(xué)模型,并用特征線法以及ADINA有限元方法對(duì)水擊數(shù)學(xué)模型進(jìn)行了求解。通過(guò)本文研究所得到的一些認(rèn)識(shí),對(duì)實(shí)際生產(chǎn)現(xiàn)場(chǎng)井口裝備的配置、溢流關(guān)井方式的選擇等具有一定指導(dǎo)意義。詳細(xì)的分析了彈性模量、管道尺寸、氣體百分含量、固體顆粒含量等因素對(duì)水擊效應(yīng)的影響,其中影響最大的是氣體百分含量和固體顆粒含量。 其次,以實(shí)際生產(chǎn)現(xiàn)場(chǎng)的溢流關(guān)井為物理模型,在一定假毆的基礎(chǔ)上,建立了比以往模型能更加真實(shí)反映溢流關(guān)井水擊效應(yīng)的數(shù)學(xué)模型,即連續(xù)性方程、運(yùn)動(dòng)方程及定解條件,在所建立的數(shù)學(xué)模型里考慮了摩擦阻力的影響。用所建立的模型及其解法進(jìn)行的計(jì)算充分表明:1)“硬關(guān)井”、“半軟關(guān)井”、“軟關(guān)井”井內(nèi)水擊壓力逐漸減??; 2)由于耗散使井內(nèi)水擊波動(dòng)由井口、套管鞋到井底逐漸減?。?)井內(nèi)為兩相流時(shí)產(chǎn)生的水擊壓力比單相流更小,氣體有減小水擊壓力的作用。計(jì)算結(jié)果表明,ADINA與本文建立的水擊數(shù)學(xué)模型的計(jì)算結(jié)果吻合較好。在分析了常規(guī)的水擊控制措施基礎(chǔ)上,大膽借用其它工程中通過(guò)安裝一個(gè)空氣罐來(lái)減小水擊壓力的方法,提出在井口裝置上也安裝一個(gè)空氣罐來(lái)控制關(guān)井水擊的理論嘗試。只是考慮到現(xiàn)場(chǎng)井口已經(jīng)比較復(fù)雜,對(duì)于該嘗試是否可行,經(jīng)濟(jì)上是否有益還需要進(jìn)~步的研究以及實(shí)驗(yàn)論證。硬關(guān)井。水擊控制 Abstract When the additional gas influx OCCURS in the bottom of a well,we must close the well right now, The water hammer should be considered while close the well in order to prevent the water hammer pressure from wrecking the formation and the blowout preventer(BOP).After analyzing factors impacting the water hammer, the paper set up the water hammer mathematic model,apply character line method and ADINA software to solve model.Then the theoretic calculation show that the atmosphere jar can decrease the water hammer pressure and the engineering meaning of research water hammer has been brought forward:On the one side,the water hammer is an important reference of closure method;On the other hand,the water hammer is helpful to the wellhead BOP choice. Firstly,The paper describes briefly the basic theories of current water hammer calculation including both water hammer mathematic model and calculative methods;calculative methods of the equation being scarcely precise.Moreover, detailed analyzing factors impacting the water hammer.Those factors include elasticity module、pipeline size、gas content、solid grain content,act,The paper regard the gas content and solid grain content as the most important factor.As solid grain content rise,the pressure wave propagation velocity go up,however, as gas content rise,the wave velocity go down. Secondly,The paper present the new water hammer mathematic model including all kinds of boundary conditions based on closure well physical model the water hammer mathematic model includes continuity equation and movement equation thinking of the friction in the process of producing water hammer pressure functions。 hard shut in。water hammer control目 錄第1章 概述1第2章 井控基本概念及井控技術(shù)2 井控基本概念及井控的三