Increased oil recovery from mature oil fields using gelled polymer treatments

Abstract

Gelled polymer treatments are applied to oil reservoirs to increase oil production and to reduce water production by altering the fluid movement within the reservoir. This research program is aimed at reducing barriers to the widespread use of these treatments by developing methods to predict gel behavior during placement in matrix rock and fractures, determiningg the persistence of permeability reduction after gel placement, and by developing methods to design production well treatments to control water production. This report describes the progress of the research during the first six months of work. A Dawn EOS multi-angle laser light scattering detector was purchased, installed and calibrated. Experiments were conducted to determine the permeabilities of a bulk gel and of a filter cake which forms when a gel is dehydrated. The pressure at which a gel in a tube is ruptured was measured and was correlated to the length and diameter of the gel. Corefloods in Berea sandstone cores were conducted to give insight into the mechanism of disproportionate permeability reduction. & automated x-y table was fabricated to allow for the determination of in-situ water saturations in sandstone slabs using microwave attenuation. Two technical papers were written.

Development of Polymer Gel Systems to Improve Volumetric Sweep and Reduce Producing Water/Oil Ratios

“…The calculated weight-average molecular weights of pre-gel aggregates as a function of reaction time agreed with the experimental data determined using a multi-angle laser light scattering technique [Willhite et al, 2002]. The model also predicted a decreasing weight fraction of small molecules and an increasing weight fraction of big molecules, i.e., a long "tail" of crosslinked polymer molecules with high molecular weights.…”

“…There are two operation modes: batch mode for measuring the weight-average molecular weight and z-average rms radius of unfractionated samples. This mode was employed in a previous study [Willhite, et al, 2002]; inline mode for measuring the molecular weight and size distributions of fractionated samples. This mode was used in this work.…”

“…The weight-average molecular weights of pre-gel aggregates were measured as a function of reaction time by a multi-angle laser light scattering (MALLS) instrument [Willhite, et al, 2002]. Experimental and calculated weight-average molecular weights of the pre-gel aggregates are plotted in Figure 2.5.…”

Evaluation of Potential of CO2-Enhanced Oil Recovery (EOR) and Assessment of Capacity for Geological Storage in a Mature Oil Reservoir within Upper Assam Basin, India

“…3 Lake et al 4 have thoroughly explained these recovery mechanisms, covering both conventional methods, such as natural flow and water flooding, and enhanced techniques like chemical, solvent, thermal, and other approaches. Green et al 5 employed frontal-advance theory to elucidate the movement of chemical substances in the oil displacement procedure during chemical injection for enhanced oil recovery (EOR). According to their findings, continuous chemical injection, such as polymer, surfactant, or a miscible solvent, may not be economically viable due to the associated high costs and risks involved.…”

“…This is achieved through various methods such as chemical injection, miscible gas injection, thermal recovery, or microbial injection. 3 Lake et al 4 have thoroughly explained these recovery mechanisms, covering both conventional methods, such as natural flow and water flooding, and enhanced techniques like chemical, solvent, thermal, and other approaches. Green et al 5 employed frontal-advance theory to elucidate the movement of chemical substances in the oil displacement procedure during chemical injection for enhanced oil recovery (EOR).…”