Due to the slim hole at the lower part of the ultra-deep and deep wells, the eccentricity and rotation of drill string and drilling fluid properties have great effects on the annular pressure drop. This leads to the f...Due to the slim hole at the lower part of the ultra-deep and deep wells, the eccentricity and rotation of drill string and drilling fluid properties have great effects on the annular pressure drop. This leads to the fact that conventional computational models for predicting circulating pressure drop are inapplicable to hydraulics design of deep wells. With the adoption of helical flow theory and H-B rheological model, a computational model of velocity and pressure drop of non-Newtonian fluid flow in the eccentric annulus was established for the cases where the drill string rotates. The effects of eccentricity, rotation of the drill string and the dimensions of annulus on pressure drop in the annulus were analyzed. Drilling hydraulics was given for an ultra-deep well. The results show that the annular pressure drop decreases with an increase in eccentricity and rotary speed, and increases with a decrease in annular flow area. There is a great difference between static mud density and equivalent circulating density during deep well drilling.展开更多
针对塔里木盆地台盆区超深小井眼定向钻井机械钻速低、钻头使用寿命短、常规螺杆钻具脱胶脱扣、钻井液稳定性差和产层喷漏同存等难题,研究形成了塔里木盆地超深小井眼定向钻井提速提效关键技术。以标准行程钻速和钻头进尺为指标,采用统...针对塔里木盆地台盆区超深小井眼定向钻井机械钻速低、钻头使用寿命短、常规螺杆钻具脱胶脱扣、钻井液稳定性差和产层喷漏同存等难题,研究形成了塔里木盆地超深小井眼定向钻井提速提效关键技术。以标准行程钻速和钻头进尺为指标,采用统计分析法优选了适用于目的层的ϕ149.2 mm/ϕ165.1 mm KS1352DGRX型钻头和ϕ120.7 mm KDM1062TR型钻头;对比国内外抗高温螺杆现状,确定了井底温度低于180℃时推荐使用国产抗高温螺杆,高于180℃时推荐使用全金属螺杆或进口耐高温螺杆;采用理论分析结合数值模拟的方法,优化设计了小尺寸降摩减阻工具,并优化了其安放位置;优选抗盐高温高压降滤失剂和抑制剂,研选除氧剂等,制定合理pH值调控和钙离子补充措施,形成了抗温200℃钻井液;分析了顺北油气田产层钻进喷漏同层的特点,确定了“降密度+井口控压+优化排量”的井控基本原则。塔里木盆地5口井应用了超深小井眼定向钻井提速提效关键技术,小井眼段平均机械钻速提高了113.24%,平均井径扩大率5.57%,平均钻井周期缩短了35.03%,均未发生井下故障和复杂情况。超深小井眼定向钻井提速提效技术为塔里木盆地勘探开发提供了技术支撑。展开更多
In this paper,the etching characteristics of the ultra-high resistivity silicon（UHRS） by using the Bosch process were investigated.The experimental results indicated that the sulfur hexafluoride flux,the temperature...In this paper,the etching characteristics of the ultra-high resistivity silicon（UHRS） by using the Bosch process were investigated.The experimental results indicated that the sulfur hexafluoride flux,the temperature of the substrate,the platen power and the etching intermittence had important influence on the etching rate and the etching morphology of the UHRS.The profiles and morphologies of sidewall were characterized with scanning electron microscopy（SEM）.By using an improved three-stage Bosch process,380-μm deep through holes were fabricated on the UHRS with the average etching rate of about 3.14 μm/min.Meanwhile,the fabrication mechanism of deep through holes on the UHRS by using the three-stage Bosch process was illustrated on the basis of the experimental results.展开更多
Growth of a black hole requires the participation of a near-by accretion disk if it is to occur at a significant rate. The Kerr solution of Einstein’s equation is a vacuum solution, but the center of a realistic Kerr...Growth of a black hole requires the participation of a near-by accretion disk if it is to occur at a significant rate. The Kerr solution of Einstein’s equation is a vacuum solution, but the center of a realistic Kerr black hole is not a vacuum, so the predicted disk singularity does not exist. Instead, the center of a black hole is occupied by an ultra-dense, spheroidal core whose diameter is greater than that of the theoretical disk singularity. The surface of a black hole’s core is continually bombarded by energetic particles from the external universe. Hence the cold remnant of a gravitationally-collapsed star that has often been assumed to be present at the center of a black hole must be replaced conceptually by a quark-gluon plasma whose temperature is of the order of 1012 K or more. The gravitational potential well of a black hole is extremely deep (TeV), but the number of discrete energy levels below the infinite-red-shift surface is finite. Information can be conveyed to observers in the external universe by thermally-excited fermions that escape from levels near the top of a black hole potential well.展开更多
基金supported by the National 863 Program (2006AA06A19-2)
文摘Due to the slim hole at the lower part of the ultra-deep and deep wells, the eccentricity and rotation of drill string and drilling fluid properties have great effects on the annular pressure drop. This leads to the fact that conventional computational models for predicting circulating pressure drop are inapplicable to hydraulics design of deep wells. With the adoption of helical flow theory and H-B rheological model, a computational model of velocity and pressure drop of non-Newtonian fluid flow in the eccentric annulus was established for the cases where the drill string rotates. The effects of eccentricity, rotation of the drill string and the dimensions of annulus on pressure drop in the annulus were analyzed. Drilling hydraulics was given for an ultra-deep well. The results show that the annular pressure drop decreases with an increase in eccentricity and rotary speed, and increases with a decrease in annular flow area. There is a great difference between static mud density and equivalent circulating density during deep well drilling.
文摘针对塔里木盆地台盆区超深小井眼定向钻井机械钻速低、钻头使用寿命短、常规螺杆钻具脱胶脱扣、钻井液稳定性差和产层喷漏同存等难题,研究形成了塔里木盆地超深小井眼定向钻井提速提效关键技术。以标准行程钻速和钻头进尺为指标,采用统计分析法优选了适用于目的层的ϕ149.2 mm/ϕ165.1 mm KS1352DGRX型钻头和ϕ120.7 mm KDM1062TR型钻头;对比国内外抗高温螺杆现状,确定了井底温度低于180℃时推荐使用国产抗高温螺杆,高于180℃时推荐使用全金属螺杆或进口耐高温螺杆;采用理论分析结合数值模拟的方法,优化设计了小尺寸降摩减阻工具,并优化了其安放位置;优选抗盐高温高压降滤失剂和抑制剂,研选除氧剂等,制定合理pH值调控和钙离子补充措施,形成了抗温200℃钻井液;分析了顺北油气田产层钻进喷漏同层的特点,确定了“降密度+井口控压+优化排量”的井控基本原则。塔里木盆地5口井应用了超深小井眼定向钻井提速提效关键技术,小井眼段平均机械钻速提高了113.24%,平均井径扩大率5.57%,平均钻井周期缩短了35.03%,均未发生井下故障和复杂情况。超深小井眼定向钻井提速提效技术为塔里木盆地勘探开发提供了技术支撑。
基金Project supported by the National Natural Science Foundation of China(Nos.61574108,61574112,61504099)
文摘In this paper,the etching characteristics of the ultra-high resistivity silicon（UHRS） by using the Bosch process were investigated.The experimental results indicated that the sulfur hexafluoride flux,the temperature of the substrate,the platen power and the etching intermittence had important influence on the etching rate and the etching morphology of the UHRS.The profiles and morphologies of sidewall were characterized with scanning electron microscopy（SEM）.By using an improved three-stage Bosch process,380-μm deep through holes were fabricated on the UHRS with the average etching rate of about 3.14 μm/min.Meanwhile,the fabrication mechanism of deep through holes on the UHRS by using the three-stage Bosch process was illustrated on the basis of the experimental results.
文摘Growth of a black hole requires the participation of a near-by accretion disk if it is to occur at a significant rate. The Kerr solution of Einstein’s equation is a vacuum solution, but the center of a realistic Kerr black hole is not a vacuum, so the predicted disk singularity does not exist. Instead, the center of a black hole is occupied by an ultra-dense, spheroidal core whose diameter is greater than that of the theoretical disk singularity. The surface of a black hole’s core is continually bombarded by energetic particles from the external universe. Hence the cold remnant of a gravitationally-collapsed star that has often been assumed to be present at the center of a black hole must be replaced conceptually by a quark-gluon plasma whose temperature is of the order of 1012 K or more. The gravitational potential well of a black hole is extremely deep (TeV), but the number of discrete energy levels below the infinite-red-shift surface is finite. Information can be conveyed to observers in the external universe by thermally-excited fermions that escape from levels near the top of a black hole potential well.
