本文關(guān)鍵詞：頁(yè)巖氣滲流數(shù)學(xué)模型，由筆耕文化傳播整理發(fā)布。

評(píng) 述

誤差.

(ⅳ) 裂縫中解吸附過(guò)程對(duì)頁(yè)巖氣產(chǎn)量的影響. 本文中基質(zhì)采用了非平衡解吸附理論, 而裂縫則采用平衡態(tài)(也即瞬時(shí))解吸附模型進(jìn)行模擬. 對(duì)比不考慮裂縫中的解吸附過(guò)程計(jì)算的累積產(chǎn)量, 結(jié)果如圖

14所示. 可以看出人工裂縫內(nèi)解吸附過(guò)程對(duì)頁(yè)巖氣產(chǎn)量幾乎沒(méi)有影響: 生產(chǎn)150天后考慮人工裂縫內(nèi)解吸附過(guò)程的累計(jì)產(chǎn)量為153492.9 m3, 不考慮人工裂縫內(nèi)解吸附過(guò)程的累計(jì)產(chǎn)量為153490.2 m3, 相差僅為2.7 m3, 這說(shuō)明人工裂縫內(nèi)的吸附氣量并不多(人工裂縫的容積本身很小), 所以人工裂縫內(nèi)的解吸附過(guò)程可以忽略.

圖14 (網(wǎng)絡(luò)版彩色)人工裂縫內(nèi)解吸附過(guò)程對(duì)頁(yè)巖氣產(chǎn)量的影響 Figure 14 (Color online) Impact of desorption process in hydraulic fracture on shale gas production

5 結(jié)論

針對(duì)頁(yè)巖氣滲流機(jī)理復(fù)雜的特點(diǎn), 綜合考慮了自由氣的黏性流動(dòng)、Knudsen擴(kuò)散、滑脫流和吸附氣的表面擴(kuò)散以及巖石變形引起的吸附氣滑移, 建立了頁(yè)巖氣滲流數(shù)學(xué)模型, 采用非線(xiàn)性非平衡Langmuir吸附理論分析了滲流過(guò)程中的解吸附機(jī)理. 通過(guò)數(shù)值模擬, 得到以下結(jié)論:

自由氣的黏性流動(dòng)與Knudsen擴(kuò)散主導(dǎo)頁(yè)巖氣產(chǎn)量, 無(wú)因次變量既可分析主導(dǎo)流動(dòng)機(jī)制, 也可計(jì)算等效滲透率.

(3) 非平衡解吸附過(guò)程相較于傳統(tǒng)瞬時(shí)解吸附理論, 會(huì)降低頁(yè)巖氣產(chǎn)量, 解吸附速率越慢, 頁(yè)巖氣產(chǎn)量越低.

(4) 由于人工裂縫容積有限, 在模擬多級(jí)壓裂水平井頁(yè)巖氣產(chǎn)量時(shí)可以忽略人工裂縫中的解吸附過(guò)程.

(1) 頁(yè)巖氣在原始儲(chǔ)層條件下幾乎不流動(dòng), 在多級(jí)壓裂水平井的產(chǎn)能計(jì)算中, 可以只考慮SRV區(qū)域內(nèi)氣體的流動(dòng).

(5) 建立的數(shù)學(xué)模型能夠分析自由氣、吸附氣以及凈解吸附速率在生產(chǎn)過(guò)程中的時(shí)空分布規(guī)律, 為多級(jí)壓裂水平井中頁(yè)巖氣的滲流問(wèn)題提供了科學(xué)

(2) 數(shù)值模擬結(jié)果顯示, 吸附氣的表面擴(kuò)散與滑

移對(duì)頁(yè)巖氣產(chǎn)量的影響均在0.1%以下,

可以忽略

.

基礎(chǔ).

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評(píng) 述

Gas flow in shale reservoirs

XIA Yang1, JIN Yan1, CHEN Mian1 & CHEN KangPing1,2

1 2

State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China; School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe AZ 85287-6101, USA

This study incorporates various gas transport mechanisms in shale nanopores with nonlinear and non-equilibrium gas adsorption- desorption kinetics. We formulate a simplified model for matrix and hydraulic fractures to study the dynamic production performance of multi-stage fractured horizontal wells in shale gas reservoirs. The gas transport mechanisms include viscous flow, Knudsen diffusion of free gas, surface diffusion, and slippage of adsorbed gas whilerock deformation is coupled in the flow equations. The sensitivity of the production rate to key physical parameters is examined through numerical simulation. Our results indicate that the viscous flow and Knudsen diffusion dominate the production of shale gas. The production rate was sensitive to the desorption rate while largely unaffected by the surface diffusion and slippage of the adsorbed gas, given that the transport process of adsorbed gas is a much slower process than the diffusion of free gas.

shale gas, flow mechanism, non-equilibrium desorption, numerical simulation

doi: 10.1360/N972014-01175

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  本文關(guān)鍵詞：頁(yè)巖氣滲流數(shù)學(xué)模型，由筆耕文化傳播整理發(fā)布。