一种耐高温低伤害纳米复合清洁压裂液性能评价

针对清洁压裂液的耐温性较差、滤失量过大等问题,研制了一种新型的耐高温低伤害纳米复合清洁压裂液。实验结果发现,一定浓度的MWNT,能够与蠕虫状胶束形成更为紧密的拟交联三维网状结构且能明显增黏;采用流变性实验优化MWNT质量分数为0.3%,得出纳米复合清洁压裂液配方为3%(w)BET-12两性表面活性剂+0.3%(w)MWNT。性能评价结果表明,在170s-1、150℃下,该压裂液黏度仍能保持在20mPa·s以上;70℃时滤失量相比传统清洁压裂液大大降低;剪切恢复性能良好,体系悬砂性能好,遇地层水或原油中烃类物质能自动破胶,高效且彻底,符合施工要求;对储层伤害较小,裂缝导流能力伤害率仅有8.9%。研究表明,该纳米复合清洁压裂液适合在中高温油气田推广应用。     

Thermodynamic analysis of high-temperature regenerative organic Rankine cycles using siloxanes as working fluids

A recent novel adjustment of the Span-Wagner equation of state for siloxanes, used as working fluids in high-temperature organic Rankine cycles, is applied in a mathematical model to solve cycles under several working conditions. The proposed scheme includes a thermo-oil intermediate heat circuit between the heat source and the organic Rankine cycle. Linear and cyclic siloxanes are assayed in saturated, superheated and supercritical cycles. The cycle includes an internal heat exchanger (regenerative cycle), although a non-regenerative scheme is also solved. In the first part of the study, a current of combustion gases cooled to close to their dew point temperature is taken as the reference heat source. In the second part, the outlet temperature of the heat source is varied over a wide range, determining appropriate fluids and schemes for each thermal level. Simple linear (MM, MDM) siloxanes in saturated regenerative schemes show good efficiencies and ensure thermal stability of the working fluid.     

特低渗透砂岩油藏压裂液损害实验评价

以镇泾油田长8组砂岩油层为研究对象,探讨了压裂液损害评价方法,并进行压裂液滤液对基块岩样渗透率损害率和压裂破胶液动态滤失对造缝岩样返排恢复率测定的压裂液动态损害实验;考察了压裂液与地层流体、工作液之间的配伍性,压裂液和原油的润湿性,测定了压裂液乳化率和残渣。压裂液原胶液组成为0.4%HPG(瓜尔胶)+0.4%AS-6(季铵盐类黏土稳定剂)+0.3%CX-307(阴离子型破乳助排剂)+0.1%HCHO(杀茵剂)。实验结果表明,原油与破胶液按3:1、3:2、1:1体积比混合后的乳化率均在60%以上,而破乳率仅为12.00%～23.77%。压裂液残渣含量平均为703 mg/L,易阻塞储层渗流通道。裂缝岩样经压裂液驱替后的返排恢复率为1.48%～85.83%;当裂缝充填支撑剂后的返排恢复率为0.02%～42.9%,较单纯裂缝岩样低。基块岩样压裂液乳化损害程度强,平均损害率为89.83%;残渣液损害程度强,平均损害率为73.71%;压裂液滤液损害程度中等偏弱,平均损害率为44.85%。压裂液产生的润湿反转使岩石由水湿转化为油湿。固相侵入、碱敏、润湿反转是储层损害的主要因素。固相侵入的损害率为28.86%,润湿性相关的损害率为44.98%,基块岩样碱敏损害率26.38%、裂缝岩样为32.18%。建议采用清洁压裂降低残渣损害、选用合适的表面活性荆提高返排率,为该油田储层保护和有效开发提供支持。     

Initial Research on the Effect of Inorganic Salt on Rate of Penetration (ROP) in Drilling Fluids

The authors attempt to investigate the interaction between inorganic components of drilling fluids and sandstones as well as the influence on the rate of penetration (ROP) imposed by inorganic components. With the analysis of Zeta potential of cuttings solution, the mechanism of the experiment is initially achieved. The results show that the ROP will be enhanced by 33.7% when AlCl₃ concentration is up to 0.01 mol/L, and therefore AlCl₃ and Al₂(SO₄)₃ possess a tendency to enhance ROP. In addition, Al³⁺ enables Zeta potential of the solution containing cuttings shifted from negative value to zero, and finally to positive value by means of analyzing Zeta potential, which contributes to the significant improvement of ROP when Zeta potential is greater than ?10 mV. Higher surface free energy created by the close-to-zero Zeta potential is conducive to crushing rocks, which in turn increases the ROP and meanwhile reduces drilling costs.     

A Study on the Thixotropy of Egyptian Bentonite Suspensions

The rheology behavior of water bentonite suspensions has been studied through recording the viscosity measurements to study the thixotropy of the suspensions using local Egyptian bentonite at 5.0%, 6.40%, and 7.5.0% concentrations in the a presence of different salt concentration as 0.0 M, 0.01 M, and 0.1 M NaCl according to API stander, rheological data was calculated by viscometer, deriving first the D0 curve, from 600 to 3 rpm, followed by a typical thixotropic loop, getting the U curve from 3 to 600 rpm, and then the D curve from 600 to 3 rpm. Three rheograms have been derived for each suspension after intensive preshearing, from high to low, from low to high, and from high to low shear rates. Positive thixotropy is observed for all suspensions at 0.0 M and 0.01 M but not at 0.1 M salt concentrations. Thixotropic indexes computed from the normal thixotropic loop, low to high to low shear rates, have been computed and vary from positive to negative. The higher the bentonite concentration, the higher the index for the suspensions with no salt, while in the presence of salt, variations of the thixotropy index are obtained with the degree of variation dependent on bentonite concentration and salt concentration The suspension with no salt and 0.01 M salt exhibited thixotropy, estimated from the D0-U curves, while the 0.1-M suspensions showed no thixotropy. Thixotropy indices vary and depend on bentonite type and concentration and on the presence and amount of salt.     

RHEOLOGICAL BEHAVIOR OF BENTONITE SUSPENSIONS

ABSTRACT

The objective of this research is to investigate the concentration effect on the rheological properties of different bentonite suspensions. Experiments were performed with different bentonite type and concentrations and the results were evaluated by different rheological models (Bingham plastic, Power law, Sisco, Casson, Herchel Bulkley and Robertson Stiff) describing the flow of non-Newtonian fluids by mathematical equations in terms of shear rate and shear stress.     

Evaluation of Low-solids Mud Reological Behavior during Drilling Shale Formation and Their Effect on the Pay Zone Productivity

Abstract

The present study deals with the evaluation of rheological behavior of low-solids mud during drilling shale formation and its effect on the pay zone productivity. This study involves the preparation of shale samples (shale formation) required for the shale sloughing tests and preparation of plug samples (reservoir formation) required for the saturation tests. The shale analyzed by X-ray diffraction showed that the main constituents are montmorillonite, small amounts of kaolinite and smectite, with a little bit of illite recorded in a few samples. Also, the low-solids base mud was prepared in form unweighted then weighted by barrite and the rheological properties (density, apparent viscosity, plastic viscosity yield point, gel strength, and thixotropy) were determined for the two types; the weighted low-solids base mud was then circulated with the shale for 12, 24, 36, 48, and 60 hr using the roller oven device to determine the sloughing ratio of the shale and the rheological properties after circulation. This circulation showed that the shale sloughing ratio increased to more than 90%. Afterward, the core samples (reservoir rock) were prepared in the form of plugs according to the test requirements and their physical properties, including porosity, permeability, and resistivity, were determined through clean samples, and after saturation by low-solids mud and shaly low-solids mud, a petrographic study was carried out for the clean and saturated samples by making thin sections to show the change in the porosity. From these it was concluded that the rheological behavior of the low-solids mud during drilling shale formation affected caused formation damage and had an effect on the pay zone productivity. The recommendation for minimizing the shale affect and formation damage is to add specific chemicals to the low-solids mud system during the drilling.     

磁流变阻尼器PWM快速控制

提出了磁流变阻尼器的PWM快速控制方法，研制出了用于汽车磁流变阻尼器的电流驱动器，经实验测试，该驱动器响应速度快，输出电流可在0．1－5A范围内调节，相对误差不大于2．67％，非线性误差不大2．18％。     

白家海凸起侏罗系段(J1b1)储集层特征与含油性关系--以彩34井区为例

针对白家海凸起侏罗系J1b1段储层油水同出的情况,有必要开展储集层研究与含油性评价.本文利用岩心样品、测井及试井资料,通过各种分析、测试等手段,论述了研究区八一段碎屑岩的岩石类型、孔隙结构、物性及流体的相渗特征.发现白家海凸起八道湾组八一段存在如下油气藏特征储层的含油性与碎屑岩粒度及岩石物性具有一定的相关性;根据储层物性、微观特征,认为储层物性是影响含油气性的关键;压实作用使储层物性变差,导致含油饱和度不高;本区储层的孔隙结构特性、含油饱和度、相渗特征等决定了八一段储层的产液特征.     

用作钻井液和完井液的甲酸盐溶液

甲酸盐钻井液是2080上代开发研制的,由于价格贵,化源窄,货源窄,缺乏专业生产供应和服务公司,所以在当时应用并不广泛,现在由于生产厂家大增,且甲酸盐钻井液回收处理再利用获得成功,尤其是在许多试验井成功使用,使这一钻井,完井液体系受到普遍重视,甲酸盐钻井液的主要特性是低摩阻,低腐蚀性,抗高温,密度,良好的页岩抑制性,良好的溶垢性能和良好的配伍性,相容性,文中对甲酸的制备方法和甲酸盐溶液的配方,净化,循环再使用进行详细介绍。