Experimental study on adaptability of well pattern using sandstone plate model with ultra-low permeability

Because the porous flow state is difficult to be simulated by one-dimensional cores and two-dimensional sand filled models,this paper proposes a method of making large-scale natural outcrop flat model and defines two parameters to evaluate adaptability of different well pattern on the ultra-low permeability sandstone flat model. With natural sandstone plate model,production of different well patterns in homogeneous oil reservoirs is simulated. A concept of pressure sweep efficiency and deliverability index for researches on adaptability of well patterns are put forward. Through experiments,plane pressure gradient field of different well patterns under different drawdown pressures are measured,and then seepage areas of the models are divided into immobilized seepage area,nonlinear seepage area,and quasi-linear seepage area,with the help of small core nonlinear seepage curve. Experiments show that adaptability of inverted nine-spot equilateral well pattern is better than those of inverted nine-spot rhombus well pattern and rectangular well pattern. With the increase of drawdown pressure,deliverability index of all well patterns increases,immobilized seepage area reduces,and quasi-linear seepage area expands. At the same time,nonlinear seepage area of inverted nine-spot equilateral well pattern reduces,while those of inverted nine-spot rhombus well pattern and rectangular well pattern fluctuate as expanding first and then reducing.     

水力侵蚀下砒砂岩坡面植被格局对土壤颗粒空间分布的影响

[目的] 研究内蒙古鄂尔多斯市典型砒砂岩地区不同植被格局下表层土壤颗粒组成空间分布特征,探明水力侵蚀下土壤颗粒分选搬运机制,为该区域生态环境恢复提供理论基础。[方法] 基于野外径流小区的原位监测试验,采用三维激光扫描与地统计学相结合的方法分析自然降雨条件下,砒砂岩坡面不同植被格局对表层土壤颗粒空间分布的影响。[结果] ①均匀分布的植被格局可有效抑制坡面的产流产沙。与裸露坡面相比其侵蚀区面积、平均径流量、平均泥沙量分别降低了5.35%,63.16%,76.47%。②均匀分布的植被格局下土壤黏粒、粉粒的含量分别较雨前增加了1.3%,2.2%,砂粒含量减少了3.2%;随机分布、聚集分布的植被格局下砂粒的含量分别增加了5.8%,15.3%,使土壤质地粗化。③不同的植被格局是引起土壤颗粒空间变异的主要因素。与降雨前相比,均匀分布、随机分布的植被格局使粉粒、砂粒的块金系数变高,空间自相关性降低;聚集分布的植被格局使黏粒、粉粒的块金系数由95.06%,83.89%降为0.07%,0.06%,表现出强烈的空间自相关性。[结论] 均匀分布的植被格局对砒砂岩坡面有着良好的水土保持作用,可显著减少坡面产流产沙过程并抑制土壤粗化。     

砒砂岩地区坡面径流水动力学特性研究

【目的】研究砒砂岩地区坡面径流的侵蚀规律,为该地区坡面水蚀预报模型的建立提供理论依据。【方法】在内蒙古鄂尔多斯市准格尔旗的西召沟内,选取典型的砒砂岩沟坡,采用野外实地放水冲刷试验,对不同冲刷流量(100,150,200,250,300 L/h)和坡度(5°,15°,25°,35°)下砒砂岩坡面径流的水动力学特性进行研究。【结果】在试验的冲刷流量和坡度范围内,砒砂岩地区坡面径流流速均随冲刷流量和坡度的增加而增大,它们之间呈幂函数关系。坡面径流雷诺数(Re)为58.55~442.85,且Re随冲刷时间的延长有增大的趋势。坡面径流弗罗德数(Fr)为0.738~2.281,且Fr随着冲刷流量和坡度的增加而增大。当冲刷流量和坡度较小时,径流流态为层流和缓流;当流量和坡度较大时,径流流态为层流和急流。坡面径流Darcy-Weisbach阻力系数(f)与冲刷流量和产沙量呈反比关系。【结论】相对于其他地区,砒砂岩地区坡面径流水动力学特性有其独特的特征,研究结果可以进一步揭示该地区坡面侵蚀产流产沙机理及侵蚀动力学机制。     

坳陷湖盆斜坡带三角洲沉积微相与砂体分布研究——以陕北绥靖地区延长组长6_1油组为例

延长组长61油组是陕北绥靖地区主要目的层,研究陕北绥靖地区长61的沉积微相和砂体分布对于加快该区油气勘探与开发步伐具有重要意义。利用岩心、测井、录井、生产和分析化验资料,分析了长61油组的沉积相和测井相标志,研究区主要为三角洲(水下)分流河道和(水下)分流间湾等沉积微相,发育多条主河道,呈北东-南西向展布;砂体厚度8～20m,呈条带状分布,与沉积微相平面展布基本一致,河道砂体物性相对较好,是下一步勘探的重点区域。     

Experimental Analysis on the Deformation of Sandstone underPore Pressure and Constant Time

In order to discuss the deformation characteristics of rock mass under different water levels changing between 145 and 175 meter in the Three Gorges reservoir area, an experiment was carried out for the studying sandstone deformation under the conditions of three different axial stresses(σ1=55.54,34.18,12.82 MPa), two cyclic pore pressures(Pmin=2 MPa,Pmax=6 MPa) and two kinds of constant time(the upper limit time and the lower limit time(ΔT=120,240 s).With ε1-T curves and p-T curves, as well as p-ε1  hysteresis curves, it was found that the curves were continuous sine wave-shaped curves.At first, the strain decreased with loading pore pressure.And then, it decreased to valley value with pore pressure at stable upper limit.Next, it increased with unloading pore pressure and increased to peak value with pore pressure at stable lower limit.The p-ε1  hysteresis curves of the sandstone had two typical stages.And one was caused by the closure of some primary pores and crack under increasing compaction, in which the strain did not form obviously hysteresis curves, and the other was pore pressure coupling stage which showed obvious hysteresis curve in form of the anti-clockwise from the dispersed to the dense.In addition, Δε-n curves in four sections (loading, unloading, steady upper limit, steady lower limit) of p-ε1 curves were compared and respectively ananlyzed in the condition of various axial stress and different constant time .     

沙棘柔性坝对砒砂岩沟道泥沙粒径分布及有机质影响

为了进一步研究沙棘"柔性坝"对砒砂岩沟道泥沙的影响,基于内蒙古砒砂岩地区沙棘"柔性坝"野外试验,根据单座沙棘"柔性坝"一次降雨淤积后的试验数据,运用对比分析的方法,研究了沙棘"柔性坝"对砒砂岩沟道泥沙粒径分布及有机质的影响及其拦沙效果。结果表明:单座沙棘"柔性坝"能够提高砒砂岩沟道泥沙有机质含量,具有淤粗排细的分选功能和良好的拦沙效果。泥沙有机质从沙棘"柔性坝"上游到下游逐渐增加,沿泥沙剖面表现出先增后减的趋势;泥沙粒径从沟道上游到下游先增大后减小,沿一次降雨淤积的泥沙剖面也表现出先增后减的趋势;暴雨后沙棘"柔性坝"单位面积淤积泥沙的平均厚度为0.369m,与对比沟相比,淤积的泥沙厚度明显较高。     

砒砂岩地区3种主要树种边材液流动态特征

为深入了解砒砂岩地区主要树种的水分利用特征,以内蒙古圪秋沟小流域砒砂岩区水土保持科技示范区为研究区域,运用茎热平衡法(SHB)对沙棘、柠条、油松3种主要树种蒸腾耗水进行研究,监测3种树种的边材液流日变化及不同天气条件下的液流速率。结果表明:(1)在生长期内,3种树种的液流速率均呈单峰曲线,其到达峰值时间大体相同。(2)在晴天时,沙棘的平均液流速率最高,可达到0.117 72cm/s,而油松与柠条的液流速率相近,3种树种的日平均流速分别为0.029 01,0.018 15,0.022 03cm/s。(3)在不同天气条件下,3种树种的边材液流速率变化规律均为晴天阴天雨天,各树种达到峰值的时间也有所差异,其规律亦为晴天阴天雨天。研究结果旨在为砒砂岩地区植物水分供求关系提供数据支撑,为该地区生态恢复与环境治理提供理论依据。     

砒砂岩与沙混合比例对春玉米冠层结构及其光合特性的影响

为探明砒砂岩与沙的不同复配比例对春玉米冠层结构、光合特性与最终产量的影响,在毛乌素沙地设置砒砂岩与沙体积比分别为1∶1、1∶2和1∶5的小区试验,于2014―2015年测定春玉米株高、叶面积指数、冠层开度、穗位叶净光合速率、产量以及土壤含水量动态变化。结果表明,1∶1和1∶5两种复配土与1∶2比例复配土相比,所种植的春玉米在12叶期、抽雄期、乳熟期具有较低冠层开度,在抽雄期具有较高的叶面积指数,冠层结构更为优化,同时1∶2复配土春玉米穗位叶净光合速率在各生育期均具有一定优势,这与该比例复配土在0~120cm深度土层内更佳的保水性具有一定关系。冠层结构与光合生理上的优势导致1∶2复配土春玉米百粒质量显著高于1∶1和1∶5复配土,产量最高,是适于在毛乌素沙地推广应用的砒砂岩与沙复配比例。     

巨菌草对生态脆弱区治理与修复的研究进展

巨菌草是一种适应性广、抗逆性强和产量高的草本植物。为巨菌草在生态综合治理中应用提供参考,从巨菌草治理重金属污染和水土流失等方面对其治理和修复生态脆弱区的相关研究进行综述,并提出提高其生态治理有效性的研究发展方向。     

天府新区红砂岩边坡景观保护研究

对红砂岩坡体迅速遭到破坏的原因进行研究,并在不改变红砂岩本身色泽纹理的基础上,提出合理可行的化学试剂保护方案,得到试验验证。旨在为红砂岩坡体景观的合理预留情况及景观建设提出可靠的方案。