阳离子对交联聚合物凝胶体系性能的影响

通过室内实验研究不同阳离子浓度和类型对瓜胶、黄原胶以及部分水解聚丙烯酰胺(HPAM)交联凝胶流变性和稳定性的影响,提出利用多壁碳纳米管(MWCNT)降低阳离子负面影响的思路。交联凝胶体系中阳离子的存在会降低交联凝胶的黏度,阳离子浓度越高,黏度降低幅度越大,二价阳离子比一价阳离子降低黏度的幅度更大。阳离子会降低交联凝胶的稳定性,并且在较高盐度条件下更为严重。在HPAM凝胶中添加MWCNT,同时利用3-氨丙基三乙氧基硅烷(APTES)进行交联,MWCNT可以包围阳离子并将其从聚合物上剥离,降低阳离子与聚合物发生反应的可能性,从而使得交联凝胶黏度和破裂压力均得到提高,提高HPAM交联凝胶在不同作业条件下的稳定性,可用于相关的钻井作业。

二氧化硅纳米流体在储集层微粒运移控制中的应用

利用SiO_2纳米流体开展岩心驱替实验,通过注入SiO_2纳米流体改变孔壁的表面性质,加强颗粒与孔壁间的吸引力,克服水动力排斥力,以提高临界流速,控制储集层中微粒运移、提高注液速度。在注水过程中注入SiO_2纳米颗粒控制微粒的运移,有助于设计更高的产/注液速度。驱替实验结果表明质量分数为0.1%的SiO_2纳米流体控制微粒运移的性能最好,可将微粒运移量降低80%。增加注入流体的盐度并不能改善纳米流体控制微粒运移的性能。通过测量岩心表面的Zeta电位,得知SiO_2纳米颗粒由于带负电荷不能改变孔壁上的Zeta电位。原子力显微镜(AFM)分析证明,控制微粒运移的主要机理是SiO_2纳米流体增加了孔壁的粗糙度,需要更大的水动力才能使多孔介质中的微粒开始移动。对于所有实验都计算了微粒上的总作用力和扭矩,理论结果与实验结果吻合,计算结果表明微粒主要以滚动机理从孔壁脱落。

采用海泡石纳米颗粒控制膨润土基钻井液性能

提出在膨润土基钻井液中添加海泡石纳米颗粒来控制其性能,并通过实验研究了不同温度压力条件下海泡石纳米颗粒对膨润土基钻井液流变性、滤失性等性能的影响。测量了添加海泡石纳米颗粒前后膨润土基钻井液在不同温度压力条件下的塑性黏度、动切力和滤失量,并在储集层温度压力条件下对添加海泡石纳米颗粒前后的膨润土基钻井液进行了岩心驱替实验,对比了钻井液的滤失量及对地层的伤害程度。结果表明:添加海泡石纳米颗粒可以提高清水和盐水膨润土基钻井液的塑性黏度和动切力;海泡石纳米颗粒可以在较大的温度和压力范围内特别是高温高压条件下保持钻井液流变性的稳定;储集层温度压力条件下,海泡石纳米颗粒降低了钻井液的滤失量,抑制了砂岩岩心渗透率降低。海泡石纳米颗粒是一种理想的膨润土基钻井液添加剂。

Experimental investigation of changes in petrophysical properties and structural deformation of carbonate reservoirs

To examine the effect of pressure on pore structure and petrophysical properties of carbonate rock, the porosity, permeability, CT scanning, SEM and elastic wave velocity of two carbonate core plug samples from an oilfield in Southwest Iran were analyzed under cyclic pressure. One of the plugs was calcite and the other was dolomite with anhydrite nodules. The cyclic pressure exerted on the samples increased from 13.79 MPa to 27.58 MPa in six steps, and the variations in petrophysical properties of the two samples at different pressure loading and unloading steps were counted and analyzed. The results show that the calcite sample decreases in porosity and permeability with the increase of pressure, which is consistent with the results from compression and shear wave velocity tests. In the dolomite sample, the decreasing trend was not observed;fluctuations of compressive and shear velocities were observed during the loading stage, which may be due to different geometries of the pores and the porosity variation in the sample. Understanding the variation of carbonate petrophysical properties with pressure is helpful for optimizing reservoir development scheme.

碳酸盐岩储集层岩石物性变化与结构变形实验

为研究压力对碳酸盐岩孔隙结构、岩石物理性质等方面的影响,在压力循环加载条件下对伊朗西南部South-Pars气田下三叠统Kangan组2个碳酸盐岩柱状岩心样品进行孔隙度、渗透率、CT扫描、扫描电子显微镜(SEM)、弹性波速度等分析。在2个岩心样品中,一个样品为方解石,另一个为含硬石膏结核的白云石,分别以6个阶段循环施加13.79 MPa和27.58 MPa的负载压力,统计分析2个样品在不同压力加载/卸载阶段下的物性变化特点。结果表明,方解石样品的孔隙度和渗透率随压力载荷的增加而减小,这与纵波和横波速度测试的结果一致。在白云石样品中则没有观察到这种趋势。在纵波和横波速度分析中可观察到压力加载阶段速度发生起伏,这可能是由于孔隙具有不同几何形状和样品中的孔隙发生变化所致。研究碳酸盐岩物性随压力的变化有助于优化调整油气藏开发方案。

The effect of cations on gelation of cross-linked polymers

The effects of different cation concentrations and types on rheological property and stability of Guar, Xanthan, and Partially Hydrolyzed Polyacrylamide(HPAM) cross-linked gels were analyzed through experiments. Also, a new approach was developed to reduce the negative effects of cation by application of multi-walled carbon nano-tubes(MWCNTs). The presence of cations in cross-linked gel system will reduce the viscosity of gel, the higher the cation concentration is, the lower the viscosity will be. The bivalent cation has a greater viscosity reduction effect on gel than monovalent cation. The stability of cross-linked gels is worse with cations, this situation becomes more serious under higher salinity. MWCNTs were added to HPAM gel, cross-linked by(3-Aminopropyl) triethoxysilane(APTES), they surrounded cations and removed them from polymers and reduced the reaction possibility. This method enhances the viscosity and breakdown pressure of cross-linked gels, improves the stability of HPAM cross-linked gel under different operating conditions, and can be applied to related drilling projects.