發(fā)布時間：2018-06-24 16:47

  本文選題：頁巖 + 納米暫堵��； 參考：《成都理工大學(xué)》2017年碩士論文

【摘要】：我國頁巖氣資源量巨大,發(fā)展前景廣闊,開發(fā)過程中投入巨大,而產(chǎn)出相對較小,其中一個很重要的原因是頁巖基質(zhì)納米孔隙發(fā)育,工作液在毛細管力作用下源源不斷進入儲層,與黏土礦物作用,容易導(dǎo)致井壁失穩(wěn)、儲層損害等問題。目前,頁巖儲層鉆井過程中主要采用油基鉆井液,但其成本高,污染環(huán)境,侵入儲層后難返排,儲層損害嚴(yán)重。為了降低工作液濾液向頁巖儲層的濾失,確立了利用酸溶性納米材料暫堵納米孔隙的思路。在評價龍馬溪組露頭頁巖的物性參數(shù)、礦物組成、孔徑分布及其對滲透率貢獻率的基礎(chǔ)上,優(yōu)選了油濕型納米碳酸鈣為納米添加劑及十六烷基三甲基氯化銨為分散劑,在此基礎(chǔ)上配制的納米鉆井液的表觀粘度、塑性粘度和動切力隨納米顆粒及十六烷基三甲基氯化銨濃度的增大均先增大后降低,當(dāng)納米顆粒濃度為2%時達到最大值,API濾失量隨納米顆粒濃度的增大而逐漸降低。提出了基于壓力傳遞法測試基質(zhì)型巖心液體滲透率,并以此評價了各因素對封堵及解堵效果的影響。實驗結(jié)果表明:納米顆粒濃度為1%時,封堵效果較好,且隨著封堵時間的延長,巖心滲透率迅速降低,之后趨于平緩;壓差為2MPa條件下,利用15%的稀鹽酸酸蝕30分鐘后巖心滲透率恢復(fù)率達到83.91%~87.50%,解堵效果良好。此外,設(shè)計實驗研究了毛細管力及壓差對鉆井液濾液以及納米顆粒進入基質(zhì)孔隙的影響,結(jié)果表明當(dāng)巖心含水飽和度較小時,毛細管力起主要作用,隨著含水飽和度的逐漸增大,壓差的作用逐漸增強。納米鉆井液封堵頁巖基質(zhì)孔隙過程中,對于與納米顆粒尺寸相仿的孔隙,納米顆粒以“卡喉”形式實現(xiàn)封堵,對于尺寸較大的孔隙,納米顆粒以架橋形式實現(xiàn)封堵。納米鉆井液暫堵等效寬度為1μm左右的微裂縫實驗結(jié)果表明:納米顆粒濃度為4%時鉆井液可以實現(xiàn)有效封堵,且隨著封堵時間的延長,滲透率迅速降低,之后趨于平緩;壓差為2MPa時,利用15%的稀鹽酸酸蝕解堵,滲透率恢復(fù)率隨酸蝕時間延長而增大,1h后滲透率恢復(fù)到原始滲透率的68.09%~74.19%;增大返排壓力可以進一步提高巖心的滲透率恢復(fù)率,當(dāng)壓差達到8MPa時,滲透率恢復(fù)率突然增大的85.11%,達到較好解堵效果。納米鉆井液封堵微裂縫過程中,尺寸較大的顆粒與納米顆粒堆積在微裂縫端部,且納米顆粒充填在大顆粒堆積后剩余的空間,使封堵帶更加致密,使?jié)B透率降低,且大量的納米顆粒與少量的尺寸相對較大但比微裂縫寬度小的顆粒進入微裂縫,進一步降低微裂縫的滲透率。
[Abstract]:In China, shale gas resource is huge, the development prospect is broad, the investment in the development process is huge, but the output is relatively small, one of the important reasons is the development of shale matrix nano-pores. The working fluid enters the reservoir continuously under the action of capillary force, and the interaction with clay minerals can easily lead to wellbore instability and reservoir damage. At present, oil based drilling fluid is mainly used in the drilling process of shale reservoir, but its cost is high, the environment is polluted, it is difficult to return to discharge after invading the reservoir, and the reservoir damage is serious. In order to reduce the filtration loss of the filtrate from the working fluid to the shale reservoir, the idea of temporarily plugging the nanometer pore with the acid soluble nanomaterials was established. Based on the evaluation of physical parameters, mineral composition, pore size distribution and permeability contribution of outcrop shale in Longmaxi formation, oil wet nano-calcium carbonate was selected as nanometer additive and cetyltrimethylammonium chloride as dispersant. On this basis, the apparent viscosity, plastic viscosity and dynamic shear force of the nano-drilling fluid increased firstly and then decreased with the increase of the concentration of nano-particles and cetyltrimethylammonium chloride. When the concentration of nanoparticles is 2, the maximum value of API loss decreases with the increase of the concentration of nanoparticles. Based on the pressure transfer method, the liquid permeability of the matrix core is measured, and the influence of various factors on the plugging and plugging removal is evaluated. The experimental results show that when the concentration of nanoparticles is 1, the plugging effect is better, and with the prolongation of plugging time, the core permeability decreases rapidly and then tends to smooth, and the pressure difference is 2 MPA. The recovery rate of core permeability is 83.91and 87.50 after 30 minutes of acid etching with 15% dilute hydrochloric acid, and the plugging removal effect is good. In addition, the effects of capillary force and pressure difference on the flow of drilling fluid filtrate and nanoparticles into the matrix pore are studied experimentally. The results show that the capillary force plays a major role when the saturation of water in the core is small. With the increase of water saturation, the effect of pressure difference increases gradually. In the process of plugging shale matrix pores with nano-drilling fluid, the nano-particles can be blocked in the form of "clamping throat" for pores similar to the size of nano-particles, and for larger pores, nano-particles can be blocked in the form of bridging. The experimental results of microfracture with the equivalent width of about 1 渭 m for temporary plugging of nano-drilling fluid show that the drilling fluid can be effectively plugged when the concentration of nanoparticles is 4 渭 m, and the permeability decreases rapidly with the prolongation of plugging time, and then tends to smooth; When the pressure difference is 2 MPA, using 15% dilute hydrochloric acid to remove the plugging, the permeability recovery rate increases with the increase of acid etching time for 1 hour, and the permeability returns to 68.09% 74.19% of the original permeability, and the permeability recovery rate of the core can be further improved by increasing the backflow pressure. When the pressure difference reaches 8 MPA, the permeability recovery rate increases suddenly 85.11%, and the plugging removal effect is better. In the process of plugging micro-fracture with nano-drilling fluid, the larger particles and nanoparticles are stacked at the end of the micro-fracture, and the nano-particles fill the remaining space after the accumulation of large particles, which makes the plugging zone denser and the permeability lower. A large number of nanoparticles and a small number of particles which are relatively larger in size but smaller in the width of the microfracture enter into the microfracture and further reduce the permeability of the microfracture.
【學(xué)位授予單位】：成都理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TE254

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本文編號：2062265