靜態(tài)壓裂增透低滲煤層基礎實驗研究
發(fā)布時間：2018-10-21 10:15
【摘要】：在我國的煤系地層中貯存有豐富的煤層氣。煤層氣資源在能源領域是一種良好的清潔能源,熱值高且燃燒后無有害氣體產(chǎn)生。煤層氣的主要成分是甲烷,煤層中甲烷的異常涌出會造成瓦斯事故的發(fā)生。如果甲烷直接向空氣中排放,則會產(chǎn)生溫室效應。因此合理利用煤層氣資源不僅有利于能源的充分利用,還可以起到保護環(huán)境的目的,同時又可以避免瓦斯事故的發(fā)生實現(xiàn)煤礦的安全生產(chǎn)。我國的煤層普遍具有非均質性、滲透率低、瓦斯含量高的特點,這些特點使得直接預抽瓦斯難度大,因此提高高瓦斯低透氣性煤層的滲透率已經(jīng)成為制約礦井瓦斯抽采的瓶頸。靜態(tài)爆破技術又稱為無聲爆破,是利用靜態(tài)爆破劑與水混合后膨脹所產(chǎn)生的膨脹壓作用于藥孔孔壁使其脹裂的一種技術。靜態(tài)爆破技術具有無飛石、無爆聲、無沖擊波和爆破震動等優(yōu)點,且操作簡單、安全性高,在低滲煤層致裂增透應用方面擁有良好的前景。本文提出運用靜態(tài)壓裂技術實現(xiàn)低滲煤層增透的目的,對靜態(tài)壓裂增透低滲煤層進行了基礎實驗研究。本文主要分析了靜態(tài)壓裂的原理及壓裂過程中各階段的應力作用情況;自制了靜態(tài)壓裂劑,在確定組分的基礎上通過正交試驗初步得出了靜態(tài)壓裂劑的最優(yōu)配比;設計實驗研究了鉆孔形狀、環(huán)境溫度、生石灰粒徑、水的酸堿度對靜態(tài)壓裂劑致裂效果的影響規(guī)律。本文得到以下主要結論:(1)靜態(tài)壓裂劑的致裂原理是膨脹源Ca O與水發(fā)生水化反應生成Ca(OH)2,水化過程中壓裂劑體積增大產(chǎn)生膨脹壓作用于孔壁。在自由狀態(tài)下Ca O的水化并不能產(chǎn)生膨脹壓,只有在受限條件下才會有膨脹壓。壓裂過程分為彈性階段和非彈性階段。以圓形孔為例,彈性階段徑向應力恒為壓應力,環(huán)向應力為拉應力,鉆孔周圍各處應力相同。當膨脹壓增大到一定值時,壓裂過程進入非彈性階段,在該階段鉆孔周邊部分區(qū)域會出現(xiàn)微裂紋,該區(qū)域為損傷區(qū)。型煤的開裂和裂紋擴展方向沿著損傷區(qū)最大微裂紋產(chǎn)生的方向。(2)靜態(tài)壓裂劑的主要組分應該包括膨脹源、減水劑、緩凝劑、膠結劑等,具體成分為生石灰、萘系減水劑、葡萄糖酸鈉、硅酸鹽水泥,通過正交試驗優(yōu)選出的最佳配比為:生石灰:萘系減水劑:葡萄糖酸鈉:硅酸鹽水泥=90:3:5:7。通過XRD測試發(fā)現(xiàn),靜態(tài)壓裂劑從膨脹壓產(chǎn)生到膨脹壓完全釋放的過程中,膨脹壓增速是變化的,前期增速快后期增速較慢。(3)鉆孔形狀會對靜態(tài)壓裂劑致裂效果產(chǎn)生影響。當鉆孔為非圓孔時,在鉆孔邊緣尖點附近會形成應力集中區(qū)域,隨著膨脹壓的升高,型煤會在該應力集中區(qū)域率先出現(xiàn)開裂,裂紋沿著尖點方向擴展延伸。(4)環(huán)境溫度、生石灰粒徑、水的酸堿度都會對靜態(tài)壓裂劑致裂效果產(chǎn)生影響。環(huán)境溫度對型煤的開裂效果具有顯著的影響,20-50℃間隨著環(huán)境溫度的升高型煤的開裂時間逐漸縮短。生石灰的粒徑過大將導致靜態(tài)壓裂劑的壓裂效應無法完全釋放,用粒徑為6-18目的生石灰配制靜態(tài)壓裂劑其壓裂性能最佳。使用堿性水配制的靜態(tài)壓裂劑其壓裂性能優(yōu)于酸性水,但當堿度達到一定值時,隨著堿性的提升壓裂性能開始下降,當水的PH為8時壓裂效果最優(yōu)。
[Abstract]:Rich coal-bed gas is stored in coal-bearing strata in China. the coal bed gas resource is a good clean energy in the energy field, the heat value is high, and no harmful gas is generated after combustion. The main component of coal bed gas is methane, and the abnormal emission of methane in coal seam can cause gas accident. If methane is directly discharged into the air, the greenhouse effect will be generated. Therefore, the reasonable utilization of the coal bed gas resources is not only beneficial to the full utilization of energy, but also the purpose of protecting the environment, and meanwhile, the safety production of the coal mine can be realized by avoiding the occurrence of gas accidents. The coal seam of China is generally characterized by non-homogeneous property, low permeability and high gas content. These characteristics make the direct pre-extraction gas difficult, so the permeability of high gas and low permeability coal seam has become the bottleneck restricting mine gas extraction. The static blasting technique is also called silent blasting, which is a technique for expanding the pore wall of the medicine hole by using the expansion pressure generated by the expansion of the static blasting agent and water. The static blasting technology has the advantages of no flying rock, no explosion sound, no shock wave and blasting vibration and the like, and has the advantages of simple operation and high safety, and has good prospect in the application of low-permeability coal seam-induced cracking and thickening. In this paper, the purpose of using static fracturing technology to realize the permeability of low-permeability coal seam is put forward, and the basic experimental study is carried out on the static fracturing and permeability-increasing low-permeability coal seam. In this paper, the principle of static fracturing and the stress action of each stage in fracturing process are analyzed. The static fracturing agent is self-made, and the optimum proportion of static fracturing agent is obtained by orthogonal experiment on the basis of determining the composition. Effect of lime particle size and pH value on cracking effect of static fracturing agent. The main conclusions are as follows: (1) The crack principle of static fracturing agent is that Ca (OH) 2 is generated by hydration reaction between the expansion source Ca O and water, and the volume of the fracturing agent in the hydration process is increased to generate the expansion pressure acting on the pore wall. The hydration of the Ca O in the free state does not produce an expansion pressure, and only under restricted conditions there will be an expansion pressure. The fracturing process is divided into elastic stage and non-elastic stage. According to the circular hole, the radial stress in the elastic phase is the compressive stress, the stress of the ring is tensile stress, and the stress around the borehole is the same. when the expansion pressure is increased to a certain value, the fracturing process enters a non-elastic stage, and micro-cracks appear in the area of the peripheral part of the drilling hole at the stage, and the area is a damaged area. The cracking and crack propagation direction of briquette is along the direction of the maximum micro-crack in the damage zone. (2) The main components of static fracturing agent should include expansion source, water reducing agent, retarder, cementing agent and the like, and the concrete components are quick lime, water reducing water reducing agent, sodium gluconate and silicate cement. Sodium gluconate: Portland cement = 90: 3: 5: 7. By means of XRD, the expansion and pressure increase of static fracturing fluid from the expansion pressure to the full release of the expansion pressure is changed, and the growth rate is slower in the early stage. (3) The drilling shape will have an effect on the fracturing effect of static fracturing agent. When the drilling hole is a non-circular hole, a stress concentration area is formed near the edge tip of the drilling hole, and as the expansion pressure increases, the briquette can lead to crack in the stress concentration area, and the crack extends along the direction of the tip point. (4) The influence of ambient temperature, lime particle size and pH value of water on the cracking effect of static fracturing agent will be affected. The environmental temperature has a remarkable effect on the cracking effect of the briquette, and the cracking time of the briquette is gradually shortened at 20-50 DEG C with the increase of the ambient temperature. The fracturing effect of the static fracturing agent can not be completely released after the particle size of the calcined lime is too small, and the fracturing performance of the static fracturing agent is optimized by using the calcined lime with the grain diameter of 6-18 meshes. The fracturing performance of static fracturing agent prepared by using alkaline water is superior to that of acid water, but when the alkalinity reaches a certain value, the fracturing effect is optimal when the PH of water is 8.
【學位授予單位】：太原理工大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TD712.6
本文編號：2284796
[Abstract]:Rich coal-bed gas is stored in coal-bearing strata in China. the coal bed gas resource is a good clean energy in the energy field, the heat value is high, and no harmful gas is generated after combustion. The main component of coal bed gas is methane, and the abnormal emission of methane in coal seam can cause gas accident. If methane is directly discharged into the air, the greenhouse effect will be generated. Therefore, the reasonable utilization of the coal bed gas resources is not only beneficial to the full utilization of energy, but also the purpose of protecting the environment, and meanwhile, the safety production of the coal mine can be realized by avoiding the occurrence of gas accidents. The coal seam of China is generally characterized by non-homogeneous property, low permeability and high gas content. These characteristics make the direct pre-extraction gas difficult, so the permeability of high gas and low permeability coal seam has become the bottleneck restricting mine gas extraction. The static blasting technique is also called silent blasting, which is a technique for expanding the pore wall of the medicine hole by using the expansion pressure generated by the expansion of the static blasting agent and water. The static blasting technology has the advantages of no flying rock, no explosion sound, no shock wave and blasting vibration and the like, and has the advantages of simple operation and high safety, and has good prospect in the application of low-permeability coal seam-induced cracking and thickening. In this paper, the purpose of using static fracturing technology to realize the permeability of low-permeability coal seam is put forward, and the basic experimental study is carried out on the static fracturing and permeability-increasing low-permeability coal seam. In this paper, the principle of static fracturing and the stress action of each stage in fracturing process are analyzed. The static fracturing agent is self-made, and the optimum proportion of static fracturing agent is obtained by orthogonal experiment on the basis of determining the composition. Effect of lime particle size and pH value on cracking effect of static fracturing agent. The main conclusions are as follows: (1) The crack principle of static fracturing agent is that Ca (OH) 2 is generated by hydration reaction between the expansion source Ca O and water, and the volume of the fracturing agent in the hydration process is increased to generate the expansion pressure acting on the pore wall. The hydration of the Ca O in the free state does not produce an expansion pressure, and only under restricted conditions there will be an expansion pressure. The fracturing process is divided into elastic stage and non-elastic stage. According to the circular hole, the radial stress in the elastic phase is the compressive stress, the stress of the ring is tensile stress, and the stress around the borehole is the same. when the expansion pressure is increased to a certain value, the fracturing process enters a non-elastic stage, and micro-cracks appear in the area of the peripheral part of the drilling hole at the stage, and the area is a damaged area. The cracking and crack propagation direction of briquette is along the direction of the maximum micro-crack in the damage zone. (2) The main components of static fracturing agent should include expansion source, water reducing agent, retarder, cementing agent and the like, and the concrete components are quick lime, water reducing water reducing agent, sodium gluconate and silicate cement. Sodium gluconate: Portland cement = 90: 3: 5: 7. By means of XRD, the expansion and pressure increase of static fracturing fluid from the expansion pressure to the full release of the expansion pressure is changed, and the growth rate is slower in the early stage. (3) The drilling shape will have an effect on the fracturing effect of static fracturing agent. When the drilling hole is a non-circular hole, a stress concentration area is formed near the edge tip of the drilling hole, and as the expansion pressure increases, the briquette can lead to crack in the stress concentration area, and the crack extends along the direction of the tip point. (4) The influence of ambient temperature, lime particle size and pH value of water on the cracking effect of static fracturing agent will be affected. The environmental temperature has a remarkable effect on the cracking effect of the briquette, and the cracking time of the briquette is gradually shortened at 20-50 DEG C with the increase of the ambient temperature. The fracturing effect of the static fracturing agent can not be completely released after the particle size of the calcined lime is too small, and the fracturing performance of the static fracturing agent is optimized by using the calcined lime with the grain diameter of 6-18 meshes. The fracturing performance of static fracturing agent prepared by using alkaline water is superior to that of acid water, but when the alkalinity reaches a certain value, the fracturing effect is optimal when the PH of water is 8.
【學位授予單位】：太原理工大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TD712.6
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