發(fā)布時間：2018-11-06 12:01

【摘要】：低滲氣藏不同于常規(guī)氣藏,因其低孔低滲的特點,其滲流特征往往與常規(guī)氣藏差別較大。DH氣藏X3層平均滲透率2.05mD,屬低滲儲層；X4層平均滲透率0.1mD、X5層平均滲透率0.068mD,均屬致密低滲透儲層,儲層中的流體流動存在獨(dú)特的滲流機(jī)理。因此本文主要采用室內(nèi)物理模擬方法,分別針對氣藏主力產(chǎn)層X3、X4和X5層開展單相滲流、兩相滲流以及水鎖效應(yīng)機(jī)理研究,為該氣田開發(fā)方案設(shè)計提供機(jī)理認(rèn)識及基礎(chǔ)參數(shù)。為此,研究的重點包括(1)重點針對目標(biāo)氣藏的低滲層位開展20組巖心的單相氣體低速滲流測試,研究評價DH氣藏滑脫效應(yīng)影響。(2)利用實驗室自研異常高壓巖心驅(qū)替裝置(200℃,200MPa),在真實地層條件下開展7組巖心的應(yīng)力敏感測試(最高溫度174.2℃,最高壓力95.7MPa),研究評價開發(fā)過程中氣藏壓力下降導(dǎo)致的滲透率應(yīng)力敏感程度。(3)DH氣藏邊底水較強(qiáng),采氣過程中隨地層壓力的下降會出現(xiàn)強(qiáng)水驅(qū)現(xiàn)象,造成氣水兩相滲流。針對儲層這一滲流特征,首先建立高溫高壓水驅(qū)氣相滲測試方法,分別在常溫常壓和高溫高壓(151.8～174.2℃,37.12～54.1MPa)兩種條件下開展8組巖心的水驅(qū)氣相滲曲線測試。(4)在實際氣井開關(guān)井時,近井區(qū)容易產(chǎn)生高含水飽和度帶造成水鎖現(xiàn)象,為評價水鎖效應(yīng)傷害程度,對此創(chuàng)新性建立測試水鎖效應(yīng)及水鎖氣解封啟動壓力的測試方法(專利申請中),并開展6組巖心的水鎖傷害測試研究。本文研究取得的主要成果如下：(1)DH氣藏產(chǎn)生滑脫效應(yīng)的臨界壓力較小,應(yīng)在0.125MPa以下,對一般氣藏來講廢棄壓力應(yīng)高于此值,因此實際生產(chǎn)中可不考慮氣體滑脫效應(yīng),只做機(jī)理研究。(2)DH氣藏X3層應(yīng)力敏感平均中等偏弱,其它兩層中等偏強(qiáng),而且儲層中應(yīng)力敏感程度一般砂礫巖比砂巖強(qiáng),低滲透砂巖比高滲透砂巖強(qiáng)。(3)DH氣藏儲層巖心高溫高壓水驅(qū)氣相滲與地面常規(guī)相滲測試結(jié)果相比,平均束縛水飽和度低3%,等滲點左移8%左右,水驅(qū)效率低6-8%,水驅(qū)殘余氣飽和度高5%左右,差異較大。(4)水鎖實驗結(jié)果顯示DH氣藏水淹排水后氣相滲透率整體下降幅度在6-15%之間,水鎖氣解封啟動壓力在0.3-3.7MPa之間,但實驗巖心較短,因此啟動壓力梯度很大,水鎖后解除水鎖的難度較大。
[Abstract]:Low permeability gas reservoir is different from conventional gas reservoir, because of its low porosity and low permeability, its percolation characteristic is often different from that of conventional gas reservoir. The average permeability of X3 layer in DH gas reservoir is 2.05 mD, which belongs to low permeability reservoir. The average permeability of layer X _ 4 is 0.1mDX _ (5). The average permeability of layer X _ 5 is 0.068mD, which belongs to dense and low permeability reservoirs, and the fluid flow in the reservoir has a unique percolation mechanism. Therefore, this paper mainly adopts the method of indoor physical simulation to study the mechanism of single-phase seepage, two-phase seepage and water lock effect for the main production zones X3X _ 4 and X _ 5 of the gas reservoir, which provides the mechanism understanding and basic parameters for the design of the development plan of the gas field. Therefore, the key points of the research include: (1) to carry out 20 groups of single-phase gas low-velocity percolation tests for the low permeability layer of the target gas reservoir. The effect of slippage effect on DH gas reservoir is studied and evaluated. (2) using laboratory self-developed abnormal high-pressure core displacement device (200 鈩，

本文編號：2314200