Experimental study of secondary and tertiary modes combined low salinity water and polymer flooding in sandstone porous media

Combined low salinity water (LSW) and polymer (LSP) flooding is the most attractive method of enhanced oil recovery (EOR). Considerable research has investigated effective mechanisms of LSP flooding. In this study, 10 laboratory core flood tests were carried out to evaluate the effects of LSW injection into samples without any clay particles, the timing of LSW injection, and the advantages of adding polymer to the injection water for EOR. Secondary and tertiary LSW injections were performed on sandpack samples with different wettability states and water salinity. Tertiary LSW injection after secondary synthetic seawater (SSW) injection in oil-wet samples resulted in 13% more oil recovery, while the water-wet sample showed no effect on the oil recovery. Secondary LSW injection in oil-wet porous media improved oil recovery by 8% of the original oil in place (OOIP) more than secondary SSW injection. Tertiary LSP flooding after secondary SSW injection in the oil-wet sample provided a recovery of 67.3% of OOIP, while secondary LSW injection followed by tertiary LSP flooding yielded the maximum ultimate oil recovery of about 77% of OOIP. The findings showed that the positive EOR effects of LSW and LSP flooding were the results of wettability alteration, pH increase, improved mobility ratio, better sweep efficiency, and oil redistribution. In addition, results showed that wettability alteration is possible without the presence of clay particles. The findings of this study can help for a better understanding of fluid propagation through the porous media and an investigation of delays in reaching ultimate oil recovery.     

富县油田M区块长8低渗透油藏减氧空气驱效果评价

针对试验区块M低孔低渗、物性差及井间连通状况差等导致水驱效果差,产量递减较快等问题,为提高区块产量,考虑构造、井网完善程度的影响,利用撬装站作为注入平台,优选3口井实施减氧空气驱试验,取得了较好效果:试验区总产油量上升,注气后日产油增加0.3t,最高日增0.68t,含水率先上升后下降,由注气初期的2.3%下降至目前的1.9%,注气时能量恢复,产量上升;停注后能量下降,产量下降。持续稳定注气是井组稳产关键。气驱见效后,泵充满度提高,泵效提高,工况改善。综上,减氧空气驱相比较水驱开发具有优越性,对同类油藏开发具有一定指导意义。     

化学水-氮气交注驱油室内实验研究

以志丹油田樊川区为研究对象,进行化学水-氮气交注驱油室内实验研究。对比分析不同驱替方式下最终驱油效率的差异。纯水驱驱油效率为47.37%;化学水驱驱油效率为56.84%;纯气驱最终驱油效率26.62%;水气交替驱最终驱油效率58%;化学水气交替驱最终高驱油效率69.62%;水气交替驱油后采用一轮化学水气交替驱油最终驱油效率为73.43%,增油15.43%。     

Superabsorbent,Breathable Graphene Oxide-Based Nanocomposite Hydrogel as a Dense Membrane for Use in Protective Clothing

This study examines the synthesis, fabrication and characterization of poly acrylamido methyl propane sulfonic acid (PAMPS)/graphene oxide (GO) nanocomposites. PAMPS-GO nanocomposite hydrogel was synthesized by radical initiated polymerization and its swelling properties, water vapor permeability (WVP), and stress-strain behavior were evaluated. The swelling behavior of hydrogel nanocomposites were improved at the presence of 0.2 wt% GO, as confirmed by water uptake experiments. It should be noted that as GO loading increased, so did the WVP of the hydrogel. The stress-strain test also revealed that the incorporation of just 0.1% of GO raised the tensile strength and young modulus of the hydrogels by 42% and 37% respectively. These fabricated dense membranes can have applications in protective clothing and wound dressing.     

水驱后凝胶与表活剂交替注入驱油效果

针对裂缝性低渗透油藏注入水易沿裂缝突进、含水上升快、水驱效果不理想的情况,开展了水驱后凝胶与表活剂交替注入方式提高采收率室内实验研究。通过室内凝胶体系成胶特性和稳定性评价,筛选出与实际油藏区块注入水配伍的凝胶体系。选择甜菜碱两性表面活性剂用于活性剂驱,开展了双管并联岩心体系驱油效果研究。研究结果表明:凝胶与表活剂交替注入可明显提高注入压力,该体系的采收率平均值为12.03%,低渗岩心的采收率略高于高渗透岩心采收率。与表活剂驱、聚合物与表活剂交替注入相比,驱油效果更好,可以作为裂缝性低渗透油藏水驱后进一步提高采收率的技术。     

平面非均质油藏水气交替驱提高采收率室内实验研究

水气交替(WAG)驱提高采收率技术和应用研究在我国处于起步阶段。借助室内驱替实验,明确了WAG驱在平面非均质油藏的适应性及其提高采收率的作用机理。将并联式填砂管替代常规岩心夹持器,进一步减弱了长岩心驱替产生的末端效应和应力敏感现象,模拟真实的平面非均质油藏条件。实验结果表明,WAG驱可减缓气窜,改善吸水剖面。注入N2可加强三相分子之间的交换、扩散、渗吸作用。对于非均质性严重的储层,水气交替注入后水驱封堵高渗带,气驱驱扫小孔隙,帮助形成稳定的驱替前缘,提高低渗储层的驱油效率。     

Porous boron nitride nanofibers/PVA hydrogels with improved mechanical property and thermal stability

Polyvinyl alcohol (PVA) hydrogel is a promising material possessing good chemical stability, high water absorption, excellent biocompatibility and biological aging resistant. However, the poor mechanical performance of PVA hydrogel limits its applications. Here we report the utilization of one-dimensional (1D) BN nanofibers (BNNFs) as nanofillers into PVA matrix to prepare a novel kind of BNNFs/PVA composite hydrogel via a cyclic freezing and thawing method. For comparison, the composite hydrogels using spherical BN nanoparticles i.e. BN nanospheres (BNNSs) as fillers were also prepared. The mechanical properties, thermal stabilities and swelling behaviors of the composite hydrogels were investigated in detail. Our study indicates that the mechanical properties of the hydrogels can be improved by adding of BNNFs. After loading of BNNFs into PVA with content of 0.5?wt%, the compressive strength of the composite hydrogel increases by 252% compared with that of pure PVA hydrogel. The tensile performance of BNNFs/PVA composite hydrogels has also been improved. Impressive 87.8% increases in tensile strengths can be obtained with 1?wt% BNNFs added. In addition, with the increase of BNNFs content, the thermal stability and the swelling ratio of hydrogels are increased gradually. The swelling ratio of hydrogel increases by 56.3% with only 1?wt% BNNFs added. In comparison, the improvement effects of the BNNS fillers on the mechanical strengths and swelling ratios are much weaker. The enhanced effects of BNNFs can be ascribed to the strong hydrogen bond interaction between BNNFs and PVA. The high aspect ratios of the nanofibers should also be took into account.     

Polyvinyl alcohol/chitosan/carbon nanotubes electroactive shape memory nanocomposite hydrogels

Shape memory nanocomposite hydrogels are intelligent soft materials in which, the nanoparticles can impart desirable mechanical properties to the polymeric matrix. The main challenge is the capability to program from permanent to temporary shapes and vice versa under the direct and indirect thermal stimuli. In this work, carbon nanotubes (CNT) with a high modulus of 1 TPa, was used to mechanically reinforce polyvinyl alcohol (PVA) and polyvinyl alcohol/chitosan (PVA/Cs) hydrogel networks. Adding appropriate amount of conductor component enables the system to be electrically activated, which leads to achieving the original permanent shape without applying mechanical external force. The PVA/Cs/CNT hydrogel containing 0.25 wt% of CNT, showed electrical conductivity greater than 9 mS cm⁻¹. Because of the presence of CNT, the shape memory behavior of PVA and PVA/Cs hydrogels was improved by 170 and 260%, respectively. The electroactive shape memory nanocomposite hydrogels exhibited complete recovery under indirect stimulation by generating Joule heating in the system.     

水气交替方法在GGY油田长6油层的应用

根据鄂尔多斯盆地GGY油田区域注水开发存在的问题开展的室内外注气实验,对水气交替驱油技术在该油田的应用进行了分析,并与现场实验相结合,提出对本区超低-特低渗透储层水气交替驱的一些初步认识。     

Biodegradable poly(vinyl alcohol)-based nanocomposite film reinforced with organophilic layered double hydroxides with potential packaging application

The continuously increasing plastic wastes and diminishing fossil resources have attracted global attention into research and development of biodegradable packaging materials. In the present study, organophilic layered double hydroxides (OLDH) intercalated with aliphatic long-chain molecules as reinforcing agents were incorporated into biodegradable poly(vinyl alcohol) (PVA) matrix by a solution casting method. FTIR, XRD and SEM were performed to analyze the structure of PVA/OLDH films. The OLDH nanosheets were well-dispersed in PVA matrix and formed strong interfacial interactions with the PVA chains, leading to remarkable improvements of optical property, mechanical performance, water vapor barrier property and thermal stability. At a loading of only 2% OLDH in PVA, we observed ~67% decrease in haze and ~66% increment in tensile strength in the composite film compared with pure PVA film. Furthermore, a 24.22% decrease in water vapor permeability (enhancement in water vapor barrier property) due to the addition of 0.5 wt% OLDH and enhanced thermal stability could be observed. These results revealed that the overall performance could be improved by introducing OLDH at very low loadings and that the PVA nanocomposite films have potential for future application in packaging films. Therefore, the use of high-performance PVA/OLDH nanocomposite films can evidently promote the application of biodegradable PVA materials in packaging industry.     

沈161区块注空气开发可行性实验研究

针对沈161区块储层物性差,非均质性强等特点,在长期高压注水条件下未能取得很好的驱油效果,而注空气成本便宜,且低渗油藏空气驱有很多成功案例。采用室内物理模拟实验研究空气驱可行性。通过水、空气驱油实验,气驱采收率为65.56%,比水驱高13.5个百分点;细长管空气驱低温氧化实验研究和燃烧管高温氧化实验研究,确定空气驱安全时间是注入1.2 PV,实现高温氧化的点火温度应该在400℃以上,且越高越好。     

Comparison the properties of PVA/Na+‐MMT nanocomposite hydrogels prepared by physical and physicochemical crosslinking

A novel physicochemical crosslinked nanocomposite hydrogel based on polyvinyl alcohol (PVA) and natural Na‐montmorillonite (Na⁺‐MMT) was synthesized by chemical crosslinking of nanocomposite hydrogel followed by a freezing‐thawing process. The effects of physical crosslinking, as well as physicochemical crosslinking, on the structure, morphology, and properties (thermal, mechanical, swelling, and deswelling) of nanocomposite hydrogels were investigated and compared with each other. The structure and morphology of nanocomposites were studied by Fourier transform infrared, X‐ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy techniques. The thermal and mechanical properties of nanocomposites that were affected by physical and physicochemical crosslinking were evaluated by thermogravimetric analysis, differential scanning calorimeter, dynamic mechanical analysis, hardness test, and Water vapor transmission rate (WVTR) experiments. The results showed that the physicochemical crosslinking of a PVA nanocomposite leads to a reduction in crystallinity and melting temperature, as well as an increase in the Hardness and WVTR compared to a physically crosslinked PVA nanocomposite hydrogel. The swelling and deswelling experiments were performed using a gravimetric method, and it was shown that controlled crosslinking of PVA nanocomposite hydrogel with glutaraldehyde causes the swelling ratio to increase and the cumulative amount of water loss to decrease. The swelling (sorption) and deswelling (desorption) kinetics data for physically and physicochemical crosslinking of nanocomposite hydrogels were fitted with a fickian model. It is concluded that through control crosslinking of PVA nanocomposite can lead to a hydrogel with higher swelling capacity than that is in conventional PVA nanocomposite hydrogel. POLYM. COMPOS., 37:897–906, 2016. © 2014 Society of Plastics Engineers     

低渗透油藏泡沫驱油机理及应用现状研究

低渗透油气藏在世界范围内分布范围广,储量大,在新探明储量中占得比例越来越大,是全球油气资源增产的主要来源,合理高效的开发低渗透油藏中的油气资源,是未来面临的主要问题。泡沫驱油作为继水驱、气驱之后新的驱油方式,结合了气体和泡沫的优点,以独特的优势越来越得到人们的重视,是低渗透油藏提高采收率的又一个重要途径。分析了泡沫驱相对于其他驱油方式的优势,概述了泡沫驱油的驱油机理,简要分析了空气泡沫驱、氮气泡沫驱各自特点,对泡沫驱油在国内外油田的应用现状做了介绍。对泡沫驱油存在的问题做了阐述,并提出了泡沫驱油的发展方向。     

注CO2气驱提高采收率效果影Ⅱ向因素分析

目前油田常规注水开发难度不断增加,应用注CO2气驱技术能够有效解决注水困难等问题,提高了原油采收率。在室内实验研究的基础上,应用数值模拟技术优化了注气方式及注气时机;分析了油藏地质参数对注CO2气驱提高采收率的影响。研究表明：水气交替注入方式更优;非均质性越强,开发效果越差;油藏渗透率越大、含油饱和度越高、原油粘度越低,注CO2驱油效果越好。     

Harmless hydrogels based on PVA/Na+‐MMT nanocomposites for biomedical applications: Fabrication and characterization

A series of nanocomposite hydrogels were prepared by a freeze‐thaw process, using polyvinyl alcohol (PVA) as polymer matrix and 0–10 wt% of hydrophilic natural Na‐montmorillonite (Na⁺‐MMT), free from any modification, as composite aggregates. The effect of nanoclay content and the sonication process on the nanocomposite microstructure and morphology as well as its properties (physical, mechanical, and thermal) were investigated. The microstructure and morphology were investigated by Fourier transform infrared spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, atomic force microscopy, and X‐ray diffraction technique. The thermal stability and mechanical properties of nanocomposite hydrogels were examined using thermogravimetric analysis, differential scanning calorimetry, dynamic mechanical analysis; moreover hardness and water vapor transmission rate measurements. It was concluded that the microstructure, morphology, physical (thermal) and mechanical properties of nanocomposite hydrogels have been modified followed by addition of nanoclay aggregates. The results showed that Na⁺‐MMT may act as a co‐crosslinker. Based on the results obtained, the nanocomposite hydrogel PVA/Na⁺‐MMT synthesized by a freeze‐thaw process, appeared to be a good candidate for biomedical applications. POLYM. COMPOS., 38:1135–1143, 2017. © 2015 Society of Plastics Engineers     

三元复合驱采出水复合清水剂的研制及应用

三元复合驱采出水含油量和悬浮固体含量高,去除困难,造成处理后回注采出水含油量和悬浮固体含量严重超标。为此,研制了由pH调节剂、混凝剂和助凝剂构成的复合清水剂CF1001、CF1002和CF1003。CF系列复合清水剂在大庆油田北三西试验区一口中心井和杏二中试验站三元复合驱采出水处理中得到了成功应用,处理后采出水的含油量和悬浮固体含量分别低于水驱采出水回注高渗透率油藏的含油量（20mg/L）和悬浮固体含量（10mg/L）的控制指标。     

多注入轮次提高等流度二元驱采收率的实验研究

针对J16块试验区实施二元驱时,存在注入液在不同渗透性地层中推进速度不均匀、驱油效果变差等问题,开展了多注入轮次提高等流度二元驱采收率的室内实验研究。结果表明:在二元体系的成分和用量相同的条件下,不同注入轮次等流度二元驱采收率不同。实验条件下,四轮次注入时化学驱采出程度最高,达到35.2%,高出一轮次7.49%。多轮次注入二元体系较单轮次注入能够更好的控制含水上升速度,长时间维持较高注入压力,更大限度增强等流度驱油效果。     

江苏油田智能水驱提高采收率研究

智能水驱提高采收率技术是一种有效的剩余油挖潜措施,智能水驱能够大幅度提高采收率而且经济效益好,并且该技术能够利用现有注采井网,减少投资,不需要大量化学剂和复杂的地面处理,是一项经济、环保、易操作、潜力巨大的油田开发新技术。通过对江苏油田梁垛区块进行四种无机盐驱油实验、注入水与产出水驱油效率实验、不同比例的注入水与产出水配比驱油实验、智能水驱油效率的研究,在现有的注水开发的基础上优化注入水的矿化度,从而提高原油采收率。     

基于人造岩心研究烟道气对高渗透油藏的驱油效果

高渗透油藏具有典型的三高特征,即"高渗透率、高产能、高丰度"。我国的高渗透油气资源所占比例较低,但众多学者并没有放弃对高渗透油藏提高采收率的研究,其后期开采阶段的采收率有待进一步提高。针对大部分油藏,基于前人使用各种类型的蒸汽,复合驱油本文基于人造高渗透岩心开展烟道气驱油实验,观察注入压力和注入PV数对最终油气采收率的影响。最终优选出最佳注入压力为10.1 MPa,最佳注入PV数为3.0 PV。     

聚表剂驱采出水水质特性及处理技术研究

以聚表剂驱采出水为研究对象,开展了水质特性分析及现场水处理试验研究。研究结果表明:采出水中聚表剂质量浓度在312~656 mg/L之间,粘度在1.2~2.4 m Pa·s之间,Zeta电位在-27.0~-22.0 m V之间,粒径小于或等于10.0μm的油珠占35%以上;其油水分离难于聚驱采出水,静置沉降16 h后,水中油的质量浓度降至100 mg/L以下。传统的连续流两级沉降除油工艺累计运行24 h,出水中油的平均质量浓度为107.9 mg/L;序批流沉降除油工艺能够实现累计运行22 h内出水油的质量浓度在96 mg/L以下,处理效果优于传统的连续流两级沉降工艺。