基于自相似模型的氣井管柱中流體的近壁壓力試驗(yàn)研究

劉銘剛, 閆怡飛, 謝 巍, 王建軍, 韓生超, 楊秀娟, 閆相禎

(1.中國石油大學(xué)儲(chǔ)運(yùn)與建筑工程學(xué)院,山東青島 266580; 2.中國石油大學(xué)油氣CAE技術(shù)研究中心,山東青島 266580;3.中國石油大學(xué)機(jī)電工程學(xué)院,山東青島 266580; 4.華北油田采油工程研究院,河北任丘 062552;5.中國石油集團(tuán)石油管工程技術(shù)研究院,陜西西安 710077)

基于自相似模型的氣井管柱中流體的近壁壓力試驗(yàn)研究

劉銘剛1,2, 閆怡飛2,3, 謝 巍4, 王建軍5, 韓生超1,2, 楊秀娟1,2, 閆相禎1,2

(1.中國石油大學(xué)儲(chǔ)運(yùn)與建筑工程學(xué)院,山東青島 266580; 2.中國石油大學(xué)油氣CAE技術(shù)研究中心,山東青島 266580;3.中國石油大學(xué)機(jī)電工程學(xué)院,山東青島 266580; 4.華北油田采油工程研究院,河北任丘 062552;5.中國石油集團(tuán)石油管工程技術(shù)研究院,陜西西安 710077)

氣井管柱內(nèi)流體運(yùn)動(dòng)狀態(tài)和近壁壓力分布的確定對(duì)井筒安全和完整性評(píng)價(jià)有重要意義。從相似性原理出發(fā)設(shè)計(jì)氣井管柱流體力學(xué)試驗(yàn),通過尺寸比尺和流速控制實(shí)現(xiàn)模型與原型的幾何相似和雷諾數(shù)自相似,采用試驗(yàn)和數(shù)值計(jì)算對(duì)氣井造斜彎曲段管柱近壁壓力進(jìn)行對(duì)比研究,利用相對(duì)誤差分析驗(yàn)證試驗(yàn)的可行性。結(jié)果表明:氣井管柱室內(nèi)流體試驗(yàn)滿足雷諾數(shù)自相似下的幾何相似條件;當(dāng)取運(yùn)動(dòng)黏度為試驗(yàn)不變量時(shí),管柱近壁壓力的試驗(yàn)?zāi)M結(jié)果與數(shù)值計(jì)算結(jié)果相比偏小,當(dāng)試驗(yàn)壓差為0～20 MPa時(shí),近壁壓力最大相對(duì)誤差為4.12%,且壓差越大,相對(duì)誤差越小;隨著生產(chǎn)壓差(pp=5～20 MPa)和油管內(nèi)徑(D=76.00～157.08 mm)的增大,管柱整體近壁壓力和沿程壓力降增大;造斜彎曲段流入端的局部壓程比隨油管內(nèi)徑增大而增大,流出端規(guī)律相反。滿足幾何相似和雷諾自相似條件的管柱流體試驗(yàn)是氣井管柱近壁壓力研究的有效手段。

管柱; 流體試驗(yàn); 近壁壓力; 相似理論; 儲(chǔ)氣庫

現(xiàn)階段對(duì)氣井管柱內(nèi)流體運(yùn)動(dòng)狀態(tài)和沿程近壁壓力的研究方法主要為試驗(yàn)井檢測(cè)和數(shù)值計(jì)算。試驗(yàn)井設(shè)計(jì)施工難度高、成本巨大,且可模擬工況單一,難以作為技術(shù)創(chuàng)新和科學(xué)研究的有效手段;數(shù)值計(jì)算方法模型成熟、工況設(shè)計(jì)簡單,且結(jié)果提取和分析相對(duì)簡單,是目前廣大學(xué)者和科研機(jī)構(gòu)在油氣井井筒流體狀態(tài)研究方面的主要研究手段,然而運(yùn)存資源占用大、網(wǎng)格質(zhì)量要求高、計(jì)算效率低等缺點(diǎn)使其很難用于大井深或完整管柱段內(nèi)的流體狀態(tài)建模和計(jì)算[1-10]。有學(xué)者擬設(shè)計(jì)類似低流速輸運(yùn)管道小尺寸流體力學(xué)試驗(yàn)的氣井管柱室內(nèi)試驗(yàn),對(duì)天然氣在注采過程中的狀態(tài)進(jìn)行研究,但都受制于無法完全滿足相似性試驗(yàn)設(shè)計(jì)原理中的流體動(dòng)力學(xué)相似而止步。目前國內(nèi)外學(xué)者對(duì)室內(nèi)小尺寸流體試驗(yàn)及相應(yīng)數(shù)值試驗(yàn)的設(shè)計(jì)主要是針對(duì)低流速管流開展的,如Stack、Zhang等[11-16]對(duì)管道的彎管段流體沖蝕問題開展了研究,Elling等[17]設(shè)計(jì)了氣體在粗糙管路中的流動(dòng)狀態(tài)對(duì)比試驗(yàn),研究了管壁摩阻對(duì)管路沿程壓力分布的影響規(guī)律,Ferng等[18-19]對(duì)輸氣薄壁管道的沖蝕問題進(jìn)行數(shù)值模擬,Mazumder等[20-22]為確定管道沖蝕位置進(jìn)行了試驗(yàn)研究;Kays等[23-26]對(duì)流體流經(jīng)變徑管路和突變截面時(shí)的運(yùn)動(dòng)狀態(tài)進(jìn)行了理論和數(shù)值計(jì)算。在氣井管柱方面,比較代表性的有Savidge等[27]推導(dǎo)了理想氣體音速流動(dòng)時(shí)的運(yùn)動(dòng)狀態(tài)方程并與低速流進(jìn)行比較,Zhu等[28-30]利用計(jì)算流體力學(xué)(CFD)方法對(duì)氣體鉆井中沖蝕問題進(jìn)行了探索,練章華、王嘉淮等[31-32]分別對(duì)高壓氣井和地下儲(chǔ)氣庫井管柱氣體沖蝕問題進(jìn)行了初步研究,但都由于缺少參考試驗(yàn)無法對(duì)理論計(jì)算結(jié)果進(jìn)行驗(yàn)證。針對(duì)這些研究現(xiàn)狀,筆者設(shè)計(jì)滿足幾何相似和雷諾自相似條件的氣井管柱流體試驗(yàn),測(cè)量管柱沿程近壁壓力,研究注采壓差和油管內(nèi)徑對(duì)管柱沿程近壁壓力的影響規(guī)律,并與數(shù)值計(jì)算結(jié)果對(duì)比,通過相對(duì)誤差分析驗(yàn)證試驗(yàn)方案的可行性。

1 物理試驗(yàn)

1.1 相似性原理和模型參數(shù)

地下儲(chǔ)氣庫井注入工況下,天然氣經(jīng)壓縮機(jī)壓縮后注入井底,采出工況時(shí)天然氣自井底流向帶壓井口,可認(rèn)為天然氣在油管柱內(nèi)以壓縮狀態(tài)做單相運(yùn)動(dòng)。要使試驗(yàn)?zāi)Ｐ?用下標(biāo)m表示)與原型(用下標(biāo)p表示)具有相同的流動(dòng)規(guī)律,利用模型預(yù)測(cè)原型流場狀態(tài),模型與原型須滿足流動(dòng)相似條件,即兩個(gè)流動(dòng)在對(duì)應(yīng)時(shí)刻對(duì)應(yīng)點(diǎn)上同名物理量具有各自的比例關(guān)系。具體地,流動(dòng)相似就是要求模型與原型之間滿足幾何相似、運(yùn)動(dòng)相似和黏度相似條件?？紤]采氣工況下天然氣在管柱內(nèi)的流動(dòng)為可壓縮的等熵流動(dòng)(天然氣等熵指數(shù)n=1.27～1.30),有

p/ρn=K.

(1)

式中，K為常數(shù)。

定義雷諾數(shù)Re為決定性相似準(zhǔn)數(shù),則根據(jù)雷諾數(shù)相等得到相似條件:

Re=ρpUpLp/μp=ρmUmLm/μm.

(2)

根據(jù)流動(dòng)相似準(zhǔn)則,模型與原型的比尺須滿足的關(guān)系為

λU=λν/λL.

(3)

其中

式中,p為天然氣壓力,Pa;ρ為天然氣密度,kg·m-3;L為管路長度,m;D為管路內(nèi)徑,m;λL、λU和λν分別為幾何比尺、速度比尺和黏度比尺。

表1為試驗(yàn)管路規(guī)格與實(shí)際油管規(guī)格對(duì)照。由表1可以得到原型與模型的幾何比尺(以管柱規(guī)格Φ114.3 mm×7.37 mm為例,下同)為

λL=Lp/Lm=1200.0/40.0=28,

(4)

λL=Dp/Dm=99.56/3.556=28.

(5)

天然氣與試驗(yàn)氣體(空氣)物理參數(shù)對(duì)照如表2所示。試驗(yàn)中忽略兩種氣體黏度差異性,則原型與模型的黏度比尺滿足

λν=νp/νm=1.

(6)

由式(3)可知滿足流動(dòng)相似條件下的原型與模型的速度比尺為

λU=1/λL=28.

(7)

根據(jù)流體力學(xué)理論,當(dāng)流體運(yùn)動(dòng)進(jìn)入自模化狀態(tài)時(shí),流體紊亂程度及速度剖面幾乎不再變化,稱為流體的雷諾數(shù)自相似現(xiàn)象。由文獻(xiàn)[34-35]可知,生產(chǎn)過程中的高產(chǎn)氣井和地下儲(chǔ)氣庫井管柱內(nèi)天然氣處于完全紊流粗糙管區(qū),此時(shí)氣體滿足雷諾數(shù)自相似條件,運(yùn)動(dòng)相似條件被放松。試驗(yàn)中取模型速度參數(shù)與原型一致,即

Um=Up.

(8)

至此,滿足相似條件的氣井管柱流體試驗(yàn)?zāi)Ｐ偷靡越?。根?jù)上述相似模型,當(dāng)實(shí)際油管內(nèi)徑99.56 mm、目標(biāo)井段油管長度取1 200 m時(shí),試驗(yàn)?zāi)Ｐ蛥?shù)為:油管內(nèi)徑3.556 mm,油管長度40.0 m,入口氣體流速120 m·s-1,空氣運(yùn)動(dòng)黏度15.8 mm2·s-1。

表1 試驗(yàn)管路規(guī)格與實(shí)際油管規(guī)格對(duì)照Table 1 Specifications comparison of test tubing and actual tubing

表2 試驗(yàn)氣體物理參數(shù)Table 2 Physical and mechanical parameters of natural gas

1.2 試驗(yàn)流程設(shè)計(jì)

根據(jù)相似模型設(shè)計(jì)試驗(yàn),對(duì)沿程近壁壓力進(jìn)行測(cè)量,試驗(yàn)裝置和數(shù)據(jù)采集單元分別如圖1、 2所示。

圖1 試驗(yàn)裝置結(jié)構(gòu)框圖和現(xiàn)場照片F(xiàn)ig.1 Diagram and picture of experimental apparatus unit structure

圖2 試驗(yàn)數(shù)據(jù)采集單元結(jié)構(gòu)Fig.2 Experimental data collection unit structure

試驗(yàn)管路由空壓機(jī)、增壓泵、氣體儲(chǔ)氣罐、高壓管路、壓力表等構(gòu)成。由空壓機(jī)提供流量,用增壓泵將氣體增壓到所需壓力,儲(chǔ)氣罐穩(wěn)定流量,根據(jù)試驗(yàn)需要設(shè)置4組不同直徑的管路,用含接箍短管模擬變截面管柱段,設(shè)置切換閥門控制管路狀態(tài),注入壓力和流出壓力由壓力傳感器和差壓傳感器測(cè)量。

試驗(yàn)裝置及數(shù)據(jù)采集原理及系統(tǒng)界面如圖2所示。4路壓力信號(hào)和2路流量計(jì)信號(hào)由模擬量輸入模塊7017采集,經(jīng)7520轉(zhuǎn)換成RS232協(xié)議與計(jì)算機(jī)連接。溫度信號(hào)由7033采集。球閥由7024輸出電壓控制。應(yīng)變片數(shù)據(jù)由應(yīng)變儀采集。流體泵狀態(tài)由變頻器與計(jì)算機(jī)連接進(jìn)行控制。管路內(nèi)氣體流速由PIV粒子圖像測(cè)速儀測(cè)定并轉(zhuǎn)化為數(shù)字信號(hào)進(jìn)行輸出。

1.3 工況設(shè)置和試驗(yàn)結(jié)果

以某儲(chǔ)氣庫試驗(yàn)井S-4井身結(jié)構(gòu)為基礎(chǔ),根據(jù)實(shí)際井身數(shù)據(jù)設(shè)計(jì)試驗(yàn)管路。試驗(yàn)井為定向井,井身參數(shù)如表3所示。

表3 試驗(yàn)井S-4井身參數(shù)Table 3 Well parameters of test well S-4

試驗(yàn)井底壓力為20 MPa。設(shè)置以下試驗(yàn)工況:管柱規(guī)格分別取Φ88.9 mm×6.45 mm、Φ114.3 mm×7.37 mm、Φ139.7 mm×9.17 mm和Φ177.8 mm×10.36 mm,注氣量分別取20×104m3·d-1(對(duì)應(yīng)壓差5 MPa)、30×104m3·d-1(對(duì)應(yīng)壓差10 MPa)、40×104m3·d-1(對(duì)應(yīng)壓差15 MPa)和50×104m3·d-1(對(duì)應(yīng)壓差20 MPa)。試驗(yàn)工況如表4所示。測(cè)量造斜彎曲段(對(duì)應(yīng)井深1 200～2 400 m井段)油管柱近壁壓力沿程分布,結(jié)果如表5所示。

表4 試驗(yàn)工況設(shè)置Table 4 Test conditions

表5 造斜彎曲段油管近壁壓力Table 5 Near-wall pressure of whipstocking segment

2 數(shù)值模擬

2.1 數(shù)值模型

為了對(duì)物理試驗(yàn)進(jìn)行修正,基于ANSYS CFX/CFD模塊對(duì)表4中井身參數(shù)進(jìn)行數(shù)值建模和計(jì)算?；贑FX/CFD的數(shù)值計(jì)算方法作為目前高速管流研究的有效手段,其在氣井管柱沿程流體壓力計(jì)算的精度和可靠性已經(jīng)驗(yàn)證[25-26]。管柱幾何模型和單元?jiǎng)澐秩鐖D3所示。模型以入口端面為源面,采用六面體網(wǎng)格進(jìn)行單元?jiǎng)澐?彎曲管柱段采用楔形網(wǎng)格過渡和加密。設(shè)置管柱流入、流出端為壓力邊界,壓縮機(jī)出口(流入端)壓力恒定,參考環(huán)境溫度(56.25 ℃)。假定油管壁面無滑移,選用Segregated Solver算法求解。

2.2 模型理論

引入Renormalization-group(RNG)k-ε渦黏湍流模型[28-30],該模型的連續(xù)方程和運(yùn)動(dòng)方程分別為

(9)

(10)

式中,xi,j,w對(duì)應(yīng)空間坐標(biāo)系中的i,j,w方向;Ui,j,w為流體在i,j,w方向上的瞬時(shí)速度分量;SM為體積力;ρ為相對(duì)密度;μeff為有效動(dòng)力黏度,數(shù)值上等于分子(動(dòng)力)黏度μ與湍流黏度μt之和;p為靜壓。

對(duì)實(shí)際可壓縮流體修正為

(11)

式中,p0為流體不可壓縮時(shí)的靜壓。

圖3 數(shù)值模型及網(wǎng)格劃分Fig.3 Meshes of tubing and packer model

(12)

由傳遞方程[31-32]

Gw+Gb-YM-ρε,

(13)

(14)

可得到湍動(dòng)能k和湍動(dòng)能耗散率ε,至此方程(8)、(9)封閉。

其中

2.3 計(jì)算結(jié)果

日注氣量為40×104m3,井斜角為23.6°(最大狗腿度為9°/30 m),采用Φ114.3 mm×7.37 mm油管時(shí),試驗(yàn)井油管柱內(nèi)天然氣近壁壓力的截面分布如圖4所示。從圖4可以看出:(1)管柱近壁壓力沿程分布受井身結(jié)構(gòu)影響很大。高速天然氣流入造斜段時(shí),管柱外壁壓力增大,內(nèi)壁壓力減小;(2)天然氣流出造斜段時(shí),壓力分布隨狗腿度減小逐漸趨于均勻。

3 影響參數(shù)分析

3.1 注采壓差

管柱規(guī)格和井身結(jié)構(gòu)確定時(shí)(井斜角23.6°,油管Φ114.3 mm×7.37 mm),地下儲(chǔ)氣庫井筒天然氣狀態(tài)受注氣壓差影響。圖5、 6分別為地下儲(chǔ)氣庫井筒底部壓力恒定(20 MPa),注氣壓差分別為5、10、15和20 MPa時(shí),造斜彎曲段油管柱內(nèi)沿程近壁壓力的物理試驗(yàn)和數(shù)值試驗(yàn)結(jié)果。

從圖5可以看出,隨著試驗(yàn)壓差的增大,注氣過程中沿井身整體近壁壓力降Δp(管柱沿程上兩點(diǎn)間的近壁靜壓之差)增大,整體壓程比Ψ(管柱沿程上兩點(diǎn)間的近壁靜壓之差與兩點(diǎn)距離的絕對(duì)值之比)相應(yīng)增大。從圖6可以看出,試驗(yàn)壓差從5 MPa提高到20 MPa的過程中,流入端彎曲外側(cè)兩測(cè)點(diǎn)的平均壓降變化率為36.7%,彎曲內(nèi)側(cè)兩測(cè)點(diǎn)的平均壓降變化率為35.0%,相應(yīng)局部壓程比變化率為325%和257%;流出端彎曲外側(cè)兩測(cè)點(diǎn)的平均壓降變化率為8.80%,彎曲內(nèi)側(cè)兩測(cè)點(diǎn)的平均壓降變化率為6.73%,相應(yīng)局部壓程比變化率為425%和322%;說明造斜彎曲段流入、流出端的局部壓程比隨壓差增大而增大,其中彎曲外側(cè)近壁壓力相比彎曲內(nèi)側(cè)對(duì)應(yīng)位置增幅更大,因此造斜彎曲段局部最大壓降最有可能發(fā)生在流入端彎曲外側(cè)或流出端彎曲內(nèi)側(cè)。

圖4 油管內(nèi)壓力截面分布云圖Fig.4 Distribution of pressure cross section in tubing

圖5 造斜彎曲段油管柱內(nèi)沿程近壁靜壓隨壓差變化規(guī)律Fig.5 Near wall static pressure variation with pressure in tubing of whipstocking

圖6 造斜彎曲段流入、流出端局部壓程比隨壓差變化規(guī)律Fig.6 Pressure-distance rate variation with pressure in tubing of whipstocking

3.2 油管內(nèi)徑

油管規(guī)格由內(nèi)徑和壁厚確定。研究井斜角和日注氣量一定(井斜角為23.6°、注氣量40×104m3·d-1)時(shí)地下儲(chǔ)氣庫油管柱近壁壓力變化規(guī)律。圖7、 8分別為油管規(guī)格取Φ88.9 mm×6.45 mm、Φ114.3 mm×7.37 mm、Φ139.7 mm×9.17 mm、Φ177.8 mm×10.36 mm時(shí),造斜彎曲段管柱沿程近壁壓力物理試驗(yàn)和數(shù)值試驗(yàn)結(jié)果。

從圖7可以看出,隨著油管內(nèi)徑的增大,注氣過程中沿井身整體近壁壓力和壓力降增大。從圖8可以看出,油管內(nèi)徑增大時(shí),流入端彎曲外側(cè)兩測(cè)點(diǎn)的平均壓降變化率為-11.1%,彎曲內(nèi)側(cè)兩測(cè)點(diǎn)的平均壓降變化率為-11.0%,相應(yīng)局部壓程比變化率為-42.9%和-22.5%;流出端彎曲外側(cè)兩測(cè)點(diǎn)的平均壓降變化率為-4.77%,彎曲內(nèi)側(cè)兩測(cè)點(diǎn)的平均壓降變化率為-5.10%,相應(yīng)局部壓程比變化率為12.2%和25.0%;說明造斜彎曲段流入端局部壓程比隨管徑增大而減小,流出端規(guī)律相反。

圖7 造斜彎曲段油管柱內(nèi)沿程近壁靜壓隨油管內(nèi)徑變化規(guī)律Fig.7 Near wall static pressure variation with inner diameter in tubing of whipstocking

圖8 造斜彎曲段流入、流出端局部壓程比隨油管內(nèi)徑變化規(guī)律Fig.8 Pressure-distance rate variation with inner diameter in tubing of whipstocking

3.3 試驗(yàn)結(jié)果分析

從圖6、8可以看出,氣井管柱內(nèi)流體室內(nèi)小尺寸試驗(yàn)的近壁壓力分布及變化規(guī)律與數(shù)值試驗(yàn)計(jì)算結(jié)果相比數(shù)值偏小,但誤差范圍穩(wěn)定,說明當(dāng)簡化流體黏度和速度比尺時(shí),滿足幾何相似的小尺寸試驗(yàn)可以較好地描述管柱沿程近壁流體壓力分布和參數(shù)變化規(guī)律。表6列出了沿井身管柱測(cè)點(diǎn)1、2處近壁壓力的試驗(yàn)結(jié)果和數(shù)值結(jié)果對(duì)比,其他測(cè)點(diǎn)可類似處理。

從表6可以看出,對(duì)比數(shù)值結(jié)果,試驗(yàn)測(cè)得近壁壓力最大誤差為4.12%,在容許范圍內(nèi)。注氣壓差從5 MPa增大到20 MPa過程中,測(cè)點(diǎn)1和測(cè)點(diǎn)2彎曲外側(cè)靜壓的試驗(yàn)誤差從4.11%減小到2.91%,內(nèi)側(cè)靜壓的試驗(yàn)誤差從4.12%減小到2.95%,說明壓差增大,可以降低試驗(yàn)誤差;從表6中還可以看出,油管內(nèi)徑對(duì)試驗(yàn)誤差影響很小,可忽略。

表6 管柱近壁壓力的試驗(yàn)結(jié)果和數(shù)值結(jié)果對(duì)比Table 6 Near-wall pressure comparison of test and numerical results

4 計(jì)算實(shí)例對(duì)比分析

現(xiàn)場儲(chǔ)氣庫S-4井油管總長為4 805 m,井身結(jié)構(gòu)如表3所示。日注氣量40×104m3,平均狗腿度為9°/30 m,油管規(guī)格為Φ114.3 mm×7.37 mm,初始井底流壓為20 MPa,壓縮機(jī)出口壓力為35 MPa(恒定),氣體密度為0.59 kg·m-3,動(dòng)力黏度為16.07 μPa·s,運(yùn)動(dòng)黏度為22.07 mm2·s-1,比定壓熱容為2.23 kJ·kg-1·K-1,比定容熱容為1.70 kJ·kg-1·K-1。當(dāng)壓力修正系數(shù)取1.287時(shí),井下壓力探測(cè)器反饋的油管近壁壓力沿井身分布與本文中試驗(yàn)測(cè)得結(jié)果對(duì)比見圖9。由此可以看出,本文試驗(yàn)結(jié)果與現(xiàn)場實(shí)測(cè)結(jié)果吻合度較好,說明氣井管柱流體試驗(yàn)作為井下壓力檢測(cè)的輔助技術(shù),其結(jié)果可為氣井管柱設(shè)計(jì)、生產(chǎn)效果預(yù)估提供一定參考。

圖9 油管近壁壓力分布試驗(yàn)結(jié)果與現(xiàn)場測(cè)量結(jié)果對(duì)比Fig.9 Comparison of experimental results and field measurements of near-wall pressure distributions

5 結(jié) 論

(1) 氣體處于完全紊流粗糙管區(qū)時(shí)滿足雷諾數(shù)自相似條件,氣井管柱流體試驗(yàn)通過尺寸比尺實(shí)現(xiàn)幾何相似,通過流速控制實(shí)現(xiàn)雷諾數(shù)自相似。

(2) 近壁壓力的試驗(yàn)結(jié)果與數(shù)值結(jié)果相比結(jié)果偏小,但相對(duì)誤差在容許范圍內(nèi),且隨著壓差增大,試驗(yàn)誤差減小。

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(編輯 沈玉英)

Experimental study on near-wall-pressure in gas well tubing based on self-similar theory

LIU Minggang1,2, YAN Yifei2,3, XIE Wei4, WANG Jianjun5, HAN Shengchao1,2, YANG Xiujuan1,2,YAN Xiangzhen1,2

(1.CollegeofPipelineandCivilEngineeringinChinaUniversityofPetroleum,Qingdao266580,China; 2.OilandGasCAETechnologyResearchCenterinChinaUniversityofPetroleum,Qingdao266580,China; 3.CollegeofElectromechanicalEngineeringinChinaUniversityofPetroleum,Qingdao266580,China; 4.PetroleumProductionEngineeringResearchInstituteofHuabeiOilfieldCompany,Renqiu062552,China; 5.CNPCTubularGoodsResearchInstitute,Xian710077,China)

The flowing state and pressure distribution near the wall of the wellbore plays an important role in the safety and integrity assessment of gas wells. An indoor small-scale testing experiment is designed to study the flowing state in the column based on the similarity principle. The geometrical similarity between the model and the prototype, and the Reynolds number self-similarity are both realized by the size scale and velocity control. The comparative analysis in use of experimental and numerical methods is performed to study the near-wall-pressure in the bending area of the tube, and the feasibility of the experiment is verified by the relative error analysis. The result shows that, the experiment satisfies the geometry similar conditions and self-similarity of Reynolds number. The experimental results of the near-wall-pressure is smaller than the numerical simulation result when the kinematics viscosity is taken as an invariable. The maximum experimental error is 4.12% when the working pressure is less than 20 MPa and the experimental error decreases with the increase of the working pressure. With the increase of the production pressure (pp=5 ～ 20 MPa) and the tubing diameter (D=76.00 ～ 157.08 mm), the near-wall-pressure and pressure-fall of the tubing also increase. The pressure-distance rate of the inflow end in the bending segment increases with the increase of the deviation angle and tubing diameter, while that of the outflow end is on the contrary. Conclusions can be drawn that the fluid in tubing experiment satisfying the geometric similarity and Reynold self-similarity is an efficient way to investigate the near-wall-pressure.

tubing; fluid experiment; near-wall-pressure; similarity theory; underground gas storage

2016-05-22

國家自然科學(xué)基金項(xiàng)目(51274231,51374228,U1262208);中央高校基本科研業(yè)務(wù)費(fèi)專項(xiàng) (15CX06067A);國家油氣重大專項(xiàng) (2016ZX05017-003-01);中石油“十三五”基礎(chǔ)課題 (2016A-3905)

劉銘剛(1990-),男,博士研究生,研究方向?yàn)橛蜌夤こ塘W(xué)、機(jī)械強(qiáng)度及可靠性。E-mail:liuminggang0303@126.com。

閆怡飛(1984-),男,博士,研究方向?yàn)橛蜌獍踩こ?。E-mail:yanyf163@163.com。

1673-5005(2017)02-0147-09

10.3969/j.issn.1673-5005.2017.02.018

TE 38

A

劉銘剛,閆怡飛,謝巍,等. 基于自相似模型的氣井管柱中流體的近壁壓力試驗(yàn)研究[J]. 中國石油大學(xué)學(xué)報(bào)(自然科學(xué)版), 2017,41(2):147-155.

LIU Minggang, YAN Yifei, XIE Wei, et al. Experimental study on near-wall-pressure in gas well tubing based on self-similar theory[J]. Journal of China University of Petroleum (Edition of Natural Science), 2017,41(2):147-155.