可实现废弃水基钻井液再生利用的电化学吸附法

现有的固、液分离技术及设备均难以去除钻井液中粒径小于等于10μm的有害固相及超细微颗粒,钻井现场多采用无害化处理后填埋的方式处置,不仅资源化利用率偏低,还存在着二次污染的风险。为此,提出了采用电化学吸附法对废弃水基钻井液进行再生处理的技术思路:首先通过室内实验,在电吸附电极上施加电压,研究电压、吸附时间、膨润土浓度、极板间距及无机盐浓度对电吸附效果的影响;然后分别考察了4种常用无机盐(NaCl、KCl、CaCl_2、Na_2CO_3)在不同浓度下的电吸附极板对模拟钻井液中固相颗粒的吸附能力;最后在确定最佳电吸附条件的基础上,以国内某油田废弃聚磺钻井液为样品,验证其处理效果。结果表明:(1)电化学吸附法通过吸附去除水基钻井液中的劣质固相,实现了废弃水基钻井液的再生,提高了钻井废弃物的资源化利用率,同时也降低了后期钻井废弃物的处理量及成本;(2)含5%膨润土、2 g/LNaCl的模拟废弃钻井液最佳电吸附条件为吸附电压36 V、吸附时间5 min、极板间距5 cm;(3)上述样品经电化学吸附法处理后,1~10μm粒径劣质固相的去除率超过90%,表明该方法对于去除废弃聚磺钻井液中的劣质固相具有明显的效果。

An electrochemical adsorption method for the reuse of waste water-based drilling fluids

The harmful solids and nano-particles with particle size smaller than or equal to 10 μm can be hardly removed by means of the existing solid–liquid separation. And on drilling sites, they are mostly buried after a harmless treatment, but the resource utilization ratio is low and the risk of secondary pollution still exists. In this paper, a technical idea was proposed to carry out a reclamation treatment on the waste water-based drilling fluids by means of electrochemical adsorption. Firstly, a laboratory test was carried out to investigate the effects of voltage, adsorption time, bentonite concentration, pad spacing and inorganic salt concentration on electro adsorption results by applying voltage on electro adsorption electrode. Then, the adsorption capacity of 4 common inorganic salts (NaCl, KCl, CaCl2 and Na2CO3) to the solid particles in the simulated drilling fluid was investigated on the electro adsorption electrode at different concentrations. Finally, after an optimal electro adsorption condition was determined, the waste polysulfonate drilling fluid of a certain domestic oilfield was taken as a sample to verify such treatment effect. And the following research results were obtained. First, by means of electrochemical adsorption, the inferior solid particles in waste drilling fluids are removed through adsorption, and thus the waste drilling fluid is reclaimed and the the resource reutilization ratio of drilling waste is increased while its treatment volume and cost in the late stage is decreased. Second, the optimal electro adsorption condition of simulated waste drilling fluid with 5% bentonite and 2 g/L NaCl is adsorption voltage of 36 V, adsorption time of 5 min and pad spacing of 5 cm. And third, more than 90% of the inferior solids with a particle size range of 1–10 μm are removed after the sample is treated by means of the electrochemical adsorption. It is indicated that this proposed method plays a remarkable role in removing the inferior solids in the waste polysulfonate drilling fluids.