Print Email Facebook Twitter Polymer gels for water control: NMR and CT scan studies Title Polymer gels for water control: NMR and CT scan studies Author Al-Muntasheri, G.A. Contributor Zitha, P.L.J. (promotor) Faculty Civil Engineering and Geosciences Date 2008-09-08 Abstract As oil and gas reservoirs mature, larger volumes of water are produced. These large volumes of produced water need to be separated, processed, treated and re-injected into the reservoir. All of these processes impose extra costs to the hydrocarbon production. Water rates can increase until production from a certain field is no longer economical. Therefore, there is a need to reduce water production. Depending on the nature of the problem, mechanical or chemical methods can be applied to remediate the excessive water problem. This research focused on the use of chemical methods for water shut-off. More specifically, this work is concerned with polymer gels for totally blocking excessive water production. Polymer gels are widely utilized for water shut-off. These chemicals are based on a polymer, a cross-linker and water. The solution is mixed at the surface. In such a case, it is a liquid. Then, this liquid (referred to as gelant) is injected into the target zone of the reservoir. After that, the well is shut-in for a certain time. During this shut-in time, the polymer and the cross-linker of the said gelant react to form a gel. Once the well is put back on production, the formed gel blocks the water flow. In fact, gels can also be applied in injection wells to divert water flow to less permeable zones in order to improve reservoir sweep efficiency. Research presented in this thesis established a systematic investigation methodology for an existing water shut-off chemical. A widely applied chemical is the polyacrylamide tert-butyl acrylate (PAtBA) cross-linked with polyethyleneimine (PEI). First, the gelation mechanisms of this system were explored in terms of published literature. Then, Carbon-13 Nuclear Magnetic spectroscopy (C-13 NMR) was used for analyzing the structural changes of the PAtBA copolymer. Gas Chromatography was used for analyzing gas products of the PAtBA thermal decomposition with and without the presence of PEI. The NMR studies indicated that gelation can take place at the amide groups of the PAtBA. Therefore, a more cost-effective polymer to be cross-linked with PEI was proposed, namely, simple polyacrylamide homopolymer (PAM). Research was then devoted to detailed analysis of the proposed system (PAM cross-linked with PEI). Bulk studies were conducted to address its thermal stability and gelation time at various conditions. High temperature glass tubes were used for thermal stability studies and steady shear viscometry was used for measurement of gelation time. The investigation was extended to porous media where the ability of the PAM/PEI system to reduce permeability of reservoir cores was examined. The system was efficient in reducing permeability of reservoir cores to zero for 7 weeks at 90oC (194oF). The displacement of the gel from porous media with low viscosity brine was examined with the aid of Computed Tomography. The brine was found to create a flow path within the rock containing the gel after a certain yielding pressure. Then, brine followed this path where no multiple branched fingering was observed. The fingering brine saturation was measured from the CT measurements and compared to theoretical models. In addition, the pressure behavior during gel extrusion from the rock matrix was compared to existing models. The yielding pressure was found to be a function of polymer content of the cured gel. Subject water controlnmrct scan To reference this document use: http://resolver.tudelft.nl/uuid:4cbce4d4-c25d-4801-94f4-4b6e67ff75cb Part of collection Institutional Repository Document type doctoral thesis Rights (c) 2008 Al-Muntasheri, G.A. Files PDF almuntasheri_20080908.pdf 5.07 MB Close viewer /islandora/object/uuid:4cbce4d4-c25d-4801-94f4-4b6e67ff75cb/datastream/OBJ/view