SAND: An Additive for Stabilzation of Swelling Clay Soils

An experimental program carried out in this study seeks to understand the physical mechanisms of stabilization of an expansive soil by adding an inert material (sand) at various forms;mixing and intercalation layers of sand. The first aim of the study is to analyze the effect of stabilization on the variation of soil consistency. The results show a marked improvement in soil consistency. Then a study of the effect of the additives on the variation of the swelling in order to solve the lifting structures caused by this phenomenon is carried out. It can be seen that the addition of sand is capable of reducing the swelling action. We complete the study using an ultrasonic device, measuring the propagation velocities of ultrasonic pulse through the tested clay samples. This shows a change occurring in the porosity of the clay when sand is added to it. As a result some interesting conclusions concerning the expansive soil-material amendment are drawn.

Comparison of short-term and long-term performances for polymer-stabilized sand and clay

A series of tests were carried out on sulfate rich, high-plasticity clay and poorly-graded natural sand to study the effectiveness of a methylene diphenyl diisocyanate based liquid polymer soil stabilizer in improving the unconfined compressive strength （UCS） of freshly stabilized soils and aged sand specimens. The aged specimens were prepared by exposing the specimens to ultraviolet radiation, freeze-thaw, and wet-dry weathering. The polymer soil stabilizer also mitigated the swelling of the expansive clay. For clay, the observations indicated that the sequence of adding water and liquid polymer had great influence on the gained UGS of stabilized specimens. However, this was shown to be of little importance for sand. Furthermore, sand samples showed incremental gains in UCS when they were submerged in water. This increase was significant for up to 4 days of soaking in water after 4 days of ambient air curing. Conversely, the clay samples lost a large fraction of their UCS when soaked in water; however, their remaining strength was still considerable. The stabilized specimens showed acceptable endurance under weathering action, although sample yellowing due to ultraviolet radiation was evident on the surface of the specimens. Except for moisture susceptibility of the clay specimens, the results of this study suggested the liquid stabilizer could be successfully utilized to provide acceptable strength, durability and mitigated swelling.

防膨抑砂剂NTW-1及其深部稳砂技术

使丙烯酰胺、阳离子单体在水溶液中引发聚合,聚合产物再与偶联剂反应,得到主链为碳链、季铵盐基团在支链末端的阳离子聚合物,代号NTW-1.与国内外多种类似功能化学剂对比,NTW-1与国产防膨剂FSJ-03使蒙脱石晶面间距降至最小的溶液浓度小(20 g/L),处理后储层岩心对蒸馏水的渗透率下降幅度小;NTW-1的防膨率最高(离心法为93%,膨胀仪法为90%),抑砂性能最好(冲砂流出液浊度、含砂量最小);因此NTW-1被选作深部稳砂用的防膨抑砂剂.固砂剂GSJ-8的60℃固结砂抗压强度高(5.8 MPa)、渗透率保持率高(87.7%),与NTW-1配伍性良好.在填砂管中依次注入20 g/L的NTW-1溶液、50～60 g/L的GSJ-8溶液、后置液,在60℃放置48小时后,固结砂抗压强度5.0～5.7 MPa,渗透率保持率90%～96%.由NTW-1和GSJ-8组成的体系可防止深部充填砂的运移,可用于出砂不太严重的疏松砂岩油藏的深部稳砂防砂.在现场施工中,用泵车交替注入NTW-1和GSJ-8溶液,其用量由油井出砂情况计算.截止2004年底,在300余口油井进行了深部稳砂作业,施工有效率92.9%,共增产原油45万吨.表6参5.

闵桥油田防膨抑砂剂的评价与应用

闵桥油田注水井出砂严重,影响了注水井的正常注水,拟采用防膨抑砂剂对其地层进行处理。通过防膨性能、抑砂能力、注入性能三个方面对5种防膨抑砂剂进行了评价与筛选。实验表明,KD-80-2防膨抑砂剂效果最佳且注入性能好,因此选定KD-80-2为闵桥油田使用的防膨抑砂剂。通过工艺优选,推荐其使用浓度为3.5%,吸附稳定时间24h。截至2012年8月,共有5口井进行了应用,5口井均正常生产,未见出砂。

稠油油藏用防膨抑砂剂的研制与性能研究

防膨抑砂剂是用来防止储层黏土膨胀及抑制地层砂分散、运移的稠油油藏用核心添加剂。以丙烯酰胺、三甲基烯丙基氯化铵为原料,70℃下反应4 h,得到防膨抑砂剂产品。通过红外光谱、热重/差热分析对其结构进行表征,考察了反应原料、防膨抑砂剂加量对防膨效果、抑砂效果的影响。结果表明,随丙烯酰胺与三甲基烯丙基氯化铵质量比的减少,防膨率增加,当丙烯酰胺与三甲基烯丙基氯化铵质量比为7:3时,加量为0.5%的防膨抑砂剂产品防膨率为94.90%,冲出地层砂的砂粒运移程度为未处理前的4.04%。而随防膨抑砂剂加量的增大,防膨率提高,防膨抑砂剂加量以0.5%为宜。由岩心伤害性能评价结果,在30℃、120℃温度下,防膨抑砂剂对岩心渗透率伤害率较小,均小于10%。