A Novel Cationic Polymer System That Improves Acid Diversion in Heterogeneous Carbonate Reservoirs

2019 ◽  
Author(s):  
Abhishek Sarmah ◽  
Ahmed Farid Ibrahim ◽  
Hisham Nasr-El-Din ◽  
Jennifer Jackson
Keyword(s):  
Polymer System ◽  
Cationic Polymer ◽  
Carbonate Reservoirs ◽  
Acid Diversion

A New Cationic Polymer System That Improves Acid Diversion in Heterogeneous Carbonate Reservoirs

SPE Journal ◽  
2020 ◽  
Vol 25 (05) ◽  
pp. 2281-2295
Author(s):  
Abhishek Sarmah ◽  
Ahmed Farid Ibrahim ◽  
Hisham Nasr-El-Din ◽  
Jennifer Jackson
Keyword(s):  
Rheological Properties ◽  
Experimental Studies ◽  
Polymer System ◽  
Cationic Polymer ◽  
Carbonate Reservoirs ◽  
Acid System ◽  
Anionic Polymers ◽  
The Matrix ◽  
Acid Diversion ◽  
Indiana Limestone

Summary In-situ gelled acids are used for acid diversion in heterogeneous carbonate reservoirs. However, most of the gelled systems are based on anionic polymers that are difficult to clean up after the acid treatments. Residual polymer deposition leads to formation damage by blocking pore throats in the matrix. This work evaluates a new cationic-polymer acid system with self-breaking ability for application as an acid diverter in carbonate reservoirs. Experimental studies have been conducted to examine the rheological properties of these polymer-based acid systems. The apparent viscosities of the live and the partially neutralized acids at pH from 0 to 5 were measured against the shear rate (0 to 1000 s−1). The effects of salinity and temperature (80 to 250°F) on the rheological properties of the acid system were also studied. The viscoelastic properties of the gelled acid system were evaluated using an oscillatory rheometer. Dynamic sweep tests were used to determine the elastic (G′) and viscous (G″) moduli of the system. Single-coreflood experiments were conducted on Indiana limestone cores to study the nature of diversion caused by the polymer-acid system. The effect of permeability contrast on the process of diversion was investigated by conducting dual-coreflood experiments on Indiana limestone cores that had permeability contrasts of 1.5 to 20. Computed tomography (CT) scans were conducted to study wormhole propagation after acid injection for both single and dual cores. The live acid system displayed a non-Newtonian shear-thinning behavior with the viscosity declining as temperature increased. For 5 wt% hydrochloric acid (HCl) and 20 gal/t polymer content at 10 s−1, the viscosity decreased from 230 to 40 cp as the temperature increased from 88 to 250°F. Acid-spending tests demonstrated that the acid generated a gel with improved viscosity of 260 cp (at 250°F and 10 s−1) after it reached a pH of 2. The highly viscous gel plugged the wormhole and forced the acid that followed to the next higher-permeability zone. The viscosity of the gel continued to increase until it broke down to 69 cp (at 250°F and 10 s−1) at a pH of 4.8, which indicates a self-breaking system and more thorough cleanup potential. Coreflood studies indicated that the wormhole and the diversion process are dependent on the temperature and the flow rate. There was no indication of any damage caused by the system. The injected acid pore volume to breakthrough (PVBT) decreased from 2.2 to 1.4 when the temperature increased from 150 to 250°F. The strong elastic nature of the gel (G′ = 3.976 Pa at 1 Hz) formed by the partially neutralized acid system proves its suitability as a candidate for use as a diverting agent. This new acid-polymer system has significant promise for use in acid diversion to improve stimulation of carbonate reservoirs.

Laboratory Evaluation of Viscoelastic Surfactant Acid Diversion for Carbonate Reservoirs

2011 ◽  
Author(s):  
Msalli Awadh Al-Otaibi ◽  
Ghaithan A. Al-Muntasheri ◽  
Ibnelwaleed Ali Hussein ◽  
Frank Fakuen Chang
Keyword(s):  
Carbonate Reservoirs ◽  
Laboratory Evaluation ◽  
Acid Diversion ◽  
Viscoelastic Surfactant

Case Study of a Novel Acid-Diversion Technique in Carbonate Reservoirs

1999 ◽  
Author(s):  
F.F. Chang ◽  
T. Love ◽  
C.J. Affeld ◽  
J.B. Blevins ◽  
R.L. Thomas ◽  
...  
Keyword(s):  
Carbonate Reservoirs ◽  
Acid Diversion

Simultaneous Acid Diversion and Water Control in Carbonate Reservoirs: A Case History from Saudi Arabia

2007 ◽  
Author(s):  
Ali Abdullah Al-Taq ◽  
Hisham A. Nasr-El-Din ◽  
Jimmy K. Beresky ◽  
Khalid M. Naimi ◽  
Leopoldo Sierra ◽  
...  
Keyword(s):  
Saudi Arabia ◽  
Case History ◽  
Carbonate Reservoirs ◽  
Water Control ◽  
Acid Diversion

Complex formation of modified chitosan and carboxymethyl cellulose and its effect on paper properties

TAPPI Journal ◽  
2009 ◽  
Vol 8 (6) ◽  
pp. 29-35 ◽  
Author(s):  
PEDRAM FATEHI ◽  
LIYING QIAN ◽  
RATTANA KITITERAKUN ◽  
THIRASAK RIRKSOMBOON ◽  
HUINING XIAO
Keyword(s):  
Carboxymethyl Cellulose ◽  
Polymer System ◽  
Layer By Layer ◽  
Paper Strength ◽  
Anionic Polymer ◽  
Paper Properties ◽  
Modified Chitosan ◽  
Layer By Layer Assembly ◽  
Polyelectrolyte Titration ◽  
Layer Assembly

The application of an oppositely charged dual polymer system is a promising approach to enhance paper strength. In this work, modified chitosan (MCN), a cationic polymer, and carboxymethyl cellulose (CMC), an anionic polymer, were used sequentially to improve paper strength. The adsorption of MCN on cellulose fibers was analyzed via polyelectrolyte titration. The formation of MCN/CMC complex in water and the deposition of this complex on silicon wafers were investigated by means of atomic force microscope and quasi-elastic light scattering techniques. The results showed that paper strength was enhanced slightly with a layer-by-layer assembly of the polymers. However, if the washing stage, which was required for layer-by-layer assembly, was eliminated, the MCN/CMC complex was deposited on fibers more efficiently, and the paper strength was improved more significantly. The significant improvement was attributed to the extra development of fiber bonding, confirmed further by scanning electron microscope observation of the bonding area of fibers treated with or without washing. However, the brightness of papers was somewhat decreased by the deposition of the complex on fibers. Higher paper strength also was achieved using rapid drying rather than air drying.

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