Modeling Formation Damage and Wettability Alteration Induced by Asphaltene Precipitation andTheir Effects on Percolation Performances During Oil Production

Author(s):  
Binshan Ju ◽  
Jishun Qin ◽  
Xinglong Chen ◽  
Tailiang Fan ◽  
Yu-Shu Wu
2020 ◽  
Vol 39 (1) ◽  
pp. 22-28 ◽  
Author(s):  
Qian Wang ◽  
Piroska Lorinczi ◽  
Paul W. J. Glover

The blockage and alteration of wettability in reservoirs caused by asphaltene deposits are problems that contribute to poor oil recovery performance during carbon dioxide (CO2) injection. Oil production and reservoir damage are both controlled by macroscopic interlayer heterogeneity and microscopic pore-throat structure and may be optimized by the choice of flooding method. In this work, the residual oil distribution and the permeability decline caused by organic and inorganic precipitation after miscible CO2 flooding and water-alternating-CO2 (CO2-WAG) flooding have been studied by carrying out core-flooding experiments on a model heterogeneous three-layer reservoir. For CO2, flooding experimental results indicate that the low-permeability layers retain a large oil production potential even in the late stages of production, while the permeability decline due to formation damage is larger in the high-permeability layer. We found that CO2-WAG can reduce the influence of heterogeneity on the oil production, but it results in more serious reservoir damage, with permeability decline caused by CO2–brine–rock interactions becoming significant. In addition, miscible CO2 flooding has been carried out for rocks with similar permeabilities but different wettabilities and different pore-throat microstructures in order to study the effects of wettability and pore-throat microstructure on formation damage. Reservoir rocks with smaller pore-throat sizes and more heterogeneous pore-throat microstructures were found to be more sensitive to asphaltene precipitation, with corresponding lower oil recovery and greater decreases in permeability. However, it was found that the degree of water wetness for cores with larger, more connected pore-throat microstructures became weaker due to asphaltene precipitation to pore surfaces. Decreasing the degree of water wetness was found to be exacerbated by increases in the sweep volume of injected CO2 that arise from cores with larger and better connected pore throats. Erosion of water wetness is a disadvantage for enhanced oil recovery operations as asphaltene precipitation prevention and control measures become more necessary.


2020 ◽  
pp. 120-127
Author(s):  
E. N. Skvortsova ◽  
O. P. Deryugina

The article discusses the results of a study on the selection of wax inhibitors that can be used at the Kondinskoye oil field during transportation and dehydration of the emulsion.Asphaltene precipitation is one of the most serious issues in oil production. The experiment was conducted in order to select the most effective wax inhibitors. We have carried out laboratory tests to choose the most effective wax inhibitor in the conditions of oil production, collection, preparation and external transport systems at the Kondinskoye oil field. Based on the data obtained, wax inhibitor-2, wax inhibitor-4, and wax inhibitor-6 have shown the best results in ensuring the efficiency of inhibition, which should be at least 70 %, and, therefore, they can be allowed to pilot tests. The recommended initial dosage of inhibitors according to the results obtained during pilot tests should be at least 500 g/t of oil.


2021 ◽  
pp. 1-8
Author(s):  
Arley S. Carvalhal ◽  
Gloria M. N. Costa ◽  
Silvio A. B. Vieira de Melo

Summary Uncertainties regarding the factors that influence asphaltene deposition in porous media (e.g., those resulting from oil composition, rock properties, and rock/fluid interaction) strongly affect the prediction of important variables, such as oil production. Besides, some aspects of these predictions are stochastic processes, such as the aggregation phenomenon of asphaltene precipitates. For this reason, a well-defined output from an asphaltene-deposition model might not be feasible. Instead of this, obtaining the probability distribution of important outputs (e.g., permeability reduction and oil production) should be the objective of rigorous modeling of this phenomenon. This probability distribution would support the design of a risk-based policy for the prevention and mitigation of asphaltene deposition. In this paper we aim to present a new approach to assessing the risk of formation damage caused by asphaltene deposition using Monte Carlo simulations. Using this approach, the probability-distribution function of the permeability reduction was obtained. To connect this information to a parameter more related to economic concepts, the probability distribution of the damage ratio (DR) was also calculated, which is the fraction of production loss caused by formation damage. A hypothetical scenario involving a decision in the asphaltene-prevention policy is presented as an application of the method. A novel approach to model the prevention of asphaltene aggregation using inhibitors has been proposed and successfully applied in this scenario.


2008 ◽  
Vol 23 (02) ◽  
pp. 210-214 ◽  
Author(s):  
AmirMasoud Kalantari-Dahaghi ◽  
Vida Gholami ◽  
Jamshid Moghadasi ◽  
R. Abdi

2013 ◽  
Vol 52 (17) ◽  
pp. 6009-6031 ◽  
Author(s):  
Sohrab Zendehboudi ◽  
Mohammad Ali Ahmadi ◽  
Omidreza Mohammadzadeh ◽  
Alireza Bahadori ◽  
Ioannis Chatzis

2008 ◽  
Author(s):  
Ali Berkat ◽  
Khelil Kartobi ◽  
Amine Mazouzi ◽  
Okba Dhina ◽  
Hani H. Qutob ◽  
...  

Processes ◽  
2020 ◽  
Vol 8 (9) ◽  
pp. 1051 ◽  
Author(s):  
Yisheng Hu ◽  
Qiurong Cheng ◽  
Jinping Yang ◽  
Lifeng Zhang ◽  
Afshin Davarpanah

As foams are not thermodynamically stable and might be collapsed, foam stability is defined by interfacial properties and bulk solution. In this paper, we investigated foam injection and different salinity brines such as NaCl, CaCl2, KCl, and MgCl2 to measure cumulative oil production. According to the results of this experiment, it is concluded that sequential low-salinity water injections with KCl and foam flooding have provided the highest cumulative oil production in sandstone reservoirs. This issue is related to high wettability changes that had been caused by the KCl. As K+ is a monovalent cation, KCl has the highest wettability changes compared to other saline brines and formation water at 1000 ppm, which is due to the higher wettability changes of potassium (K+) over other saline ions. The interfacial tension for KCl at the lowest value is 1000 ppm and, for MgCl2, has the highest value in this concentration. Moreover, the formation brine, regarding its high value of salty components, had provided lower cumulative oil production before and after foam injection as it had mobilized more in the high permeable zones and, therefore, large volumes of oil would be trapped in the small permeable zones. This was caused by the low wettability alteration of the formation brine. Thereby, formation water flowed in large pores and the oil phase remained in small pores and channels. On the other hand, as foams played a significant role in the mobility control and sweep efficiency, at 2 pore volume, foam increased the pressure drop dramatically after brine injection. Consequently, foam injection after KCl brine injection had the maximum oil recovery factor of 63.14%. MgCl2 and formation brine had 41.21% and 36.51% oil recovery factor.


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