Gasimli Nijat, Mahmoud Mohamed, Kamal Muhammad Shahzad, Patil Shirish, Alsaiari Hamad A, Hussein Ibnelwaleed A
King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia.
Saudi Aramco, Dhahran 31311, Saudi Arabia.
ACS Omega. 2022 Jul 21;7(30):26137-26153. doi: 10.1021/acsomega.2c01568. eCollection 2022 Aug 2.
Hydrocarbon production operations include water injection, varying stimulation approaches, and enhanced oil recovery techniques. These treatments often affect reservoir formation, production, and injection facilities. Such sorts of well operations cause the formation of organic and inorganic scales in the near-wellbore region and various production and injection structures. Downhole squeeze treatment is commonly used as a control measure to prevent scale precipitation. A scale inhibitor solution is introduced into a formation by applying a squeeze treatment. The method allows scale inhibitors to adsorb on the internal rock surface to avoid settling down the scale precipitates. Thus, the study of adsorption of different types of inhibitors to prevent scale formation on the reservoir rock through the execution of downhole squeeze treatment is becoming necessary. This study incorporated different experimental techniques, including dynamic adsorption experiments of chelating agents employing a coreflooding setup, inductively coupled plasma-optical emission spectrometry (ICP-OES) to inhibit the formation of iron-containing scales in limestone rocks, and ζ-potential measurements targeting determination of iron precipitation in varying pH environments on calcite minerals. The influence of the inhibitor soaking time and salt existence in the system on chelating agent adsorption was also evaluated in the coreflooding experiments. The findings based on the coreflooding tests reveal that the concentration of chelating agents plays a significant role in their adsorption on carbonate rocks. The treatments with 20 wt % ethylenediaminetetraacetic acid (EDTA) and 20 wt % diethylenetriaminepentaacetic acid produced the highest adsorption capacity in limestone rock samples by inhibiting 84 and 85% of iron(III) ions, respectively. Moreover, the presence of the salts (CaCl and MgCl) considerably decreased the adsorption of 10 wt % EDTA to 56% (CaCl) and 52% (MgCl) and caused nearly 20% more permeability reduction, while more inhibitor soaking time resulted in comparably higher adsorption and lesser permeability diminution. The results of ζ-potential measurements showed that the pH environment controls iron(II) and (III) precipitation, and iron(III) starts to deposit from a low pH region, whereas iron(II) precipitates in increased pH environments in calcite minerals.
烃类生产作业包括注水、各种增产措施以及强化采油技术。这些处理方式常常会影响油藏地层、生产和注入设施。此类油井作业会在近井区域以及各种生产和注入结构中形成有机和无机垢。井下挤注处理通常用作防止结垢的控制措施。通过挤注处理将阻垢剂溶液注入地层。该方法可使阻垢剂吸附在岩石内部表面，以避免垢沉淀下来。因此，通过井下挤注处理研究不同类型抑制剂在储层岩石上的吸附以防止结垢变得很有必要。本研究采用了不同的实验技术，包括使用岩心驱替装置进行螯合剂的动态吸附实验、利用电感耦合等离子体发射光谱法（ICP - OES）抑制石灰岩中铁垢的形成，以及通过ζ电位测量来确定方解石矿物在不同pH环境中铁的沉淀情况。在岩心驱替实验中还评估了抑制剂浸泡时间和体系中盐分的存在对螯合剂吸附的影响。基于岩心驱替试验的结果表明，螯合剂的浓度对其在碳酸盐岩上的吸附起着重要作用。用20 wt%的乙二胺四乙酸（EDTA）和20 wt%的二乙烯三胺五乙酸处理时，在石灰岩岩样中产生了最高的吸附容量，分别抑制了84%和85%的铁（III）离子。此外，盐（CaCl和MgCl）的存在使10 wt% EDTA的吸附量大幅降低至56%（CaCl）和52%（MgCl），并导致渗透率降低近20%，而更长的抑制剂浸泡时间则导致相对更高的吸附量和更小的渗透率降低。ζ电位测量结果表明，pH环境控制着铁（II）和铁（III）的沉淀，铁（III）在低pH区域开始沉淀，而铁（II）在方解石矿物的pH升高环境中沉淀。
