Application of polymer flooding as a chemical Enhanced Oil Recovery (EOR) has increased over recent years. The main type of polymer used is partially hydrolyzed polyacrylamide (HPAM). This polymer still has some challenges especially with shear stability and injectivity that restrict its utility, particularly for low permeability reservoirs. Injectivity limits the possible gain by acceleration in oil production due to polymer flooding. Hence, good polymer injectivity is a requirement for the success of the operation. This paper aims to investigate the influence of formation permeability on polymer flow in porous media.
In this study, a combination of core flooding with rheological studies is presented to evaluate the influence of permeability on polymer in-situ rheology behavior. The in-situ flow of HPAM polymers has also been studied for different molecular weights. The effect of polymer preconditioning prior to injection was studied through exposing polymer solutions to different extent of mechanical degradation.
Results from this study reveal that the expected shear thinning behavior of HPAM that is observed in rheometer measurements is not observed in in-situ rheology in porous media. Instead, HPAM in porous media exhibits near-Newtonian behavior at low flow rates representative of velocities deep in the reservoir, while exhibiting shear thickening behavior at high flow rates representative of velocities near wellbore region. The pressure build-up associated with shear thickening behavior during polymer injection is significantly higher than pressure differential during water injection. The extent of shear thickening is high during the injection of high Mw polymer regardless of cores' permeability. In low permeable Berea cores, shear thickening and mechanical degradation occur at lower velocities although the degree of shear thickening is lower in Berea to that observed in high permeable Bentheimer cores. This is ascribed to high polymer retention in Berea cores that results in high residual resistance factor (RRF). Results show that preshearing polymer before injection into porous media optimizes its injectability and transportability through porous media. The effect of preshearing becomes favorable for the injection of high Mw polymers into low permeability formation.
This study discusses polymer in-situ rheology and injectivity, which is a key issue in the design of polymer flood projects. The results provide beneficial information on optimizing polymer injectivity, in particular, for low permeability porous media.
ExxonMobil’s hot streak of offshore discoveries have sparked investor interest in the Guyana-Suriname basin. How did the company get there, and why do industry representatives feel optimistic about future deepwater prospects in the region? In the 30 years of operations on Suriname’s Tambaredjo field, the prime mechanism for lifting the 15.6 °API crude to surface has been that of progressing cavity pumps (PCPs).
The explorer has so far encountered 400 ft of reservoir pay zone in an area where it has three other producing fields. Murphy Oil to Buy Deepwater US Gulf Assets for up to $1.625 Billion The El Dorado, Arkansas-based Murphy has quickly found a home for some of the cash it will receive from the sale of its Malaysia business. The company has been rapidly expanding its US gulf footprint while simplifying its portfolio and targeting more oil. Petrobras and Shell have brought online the Lula field’s seventh FPSO as the firms continue to ramp up production from the pre-salt Santos Basin. The French major is racking up barrels of deepwater production as part of its large-scale West African push.
The major’s dominant showing in US Gulf of Mexico Lease Sale 252 propelled another rise in bids and dollars for the biannual regionwide auction. Funding for startups in the upstream industry does not always guarantee that oil and gas companies will want to test the new technology. A new venture and accelerator model hopes to change this through guaranteed pilots. The Pluma-1 discovery could turn the southeast portion of Stabroek Block off Guyana "into a major new development area," the company says. ExxonMobil and Hess led the way in the most active regionwide US gulf lease sale thus far.
Yellowtail-1 is the fifth discovery in the Turbot area, where ExxonMobil plans another Stabroek Block development hub. Thirteen companies placed bids on 18 blocks in the Austral, North Argentina, and Malvinas West basins as part of Argentina’s first open bid round for offshore acreage in more than 20 years. Conventional oil and gas discovered resources in 2019 are on pace to rise 30% from last year and reach their highest level since the beginning of the industry downturn. Here, a recap of the first quarter's 15 biggest oil and gas discoveries, which altogether are propelling the increase. Colombia now counts Repsol, ExxonMobil, Shell, and Noble Energy as companies committed to exploration in its portion of the Caribbean Sea.
Yellowtail-1 is the fifth discovery in the Turbot area, where ExxonMobil plans another Stabroek Block development hub. Conventional oil and gas discovered resources in 2019 are on pace to rise 30% from last year and reach their highest level since the beginning of the industry downturn. Here, a recap of the first quarter's 15 biggest oil and gas discoveries, which altogether are propelling the increase. The Pluma-1 discovery could turn the southeast portion of Stabroek Block off Guyana "into a major new development area," the company says. Odds on the World vs. Permian Fight Are Narrowing While US onshore still holds an edge, international oil companies are finding attractive options for diversifying their portfolios, mixing onshore with offshore conventional fields, where finding and development costs are down, and the time it takes to bring them on line.
Keen on Anadarko for a while, Occidental Petroleum is ready to do battle with Chevron for the big independent. Murphy Oil to Buy Deepwater US Gulf Assets for up to $1.625 Billion The El Dorado, Arkansas-based Murphy has quickly found a home for some of the cash it will receive from the sale of its Malaysia business. The company has been rapidly expanding its US gulf footprint while simplifying its portfolio and targeting more oil. With the purchase, the growing, privately-held Chrysaor Holdings will expand its UK North Sea production to 185,000 BOE/D. Thirteen companies placed bids on 18 blocks in the Austral, North Argentina, and Malvinas West basins as part of Argentina’s first open bid round for offshore acreage in more than 20 years.
The paper discusses the feasibility study approach of polymer flooding enhanced oil recovery. This work is focused on understanding and quantifying key aspects of polymer flooding and design parameter optimization case. A synthetic reservoir simulation model was employed for the study.
The first stage is to identify and understand key factors that have most significant impact to polymer flooding response. There are eight parameters that are considered in the analysis, such as polymer concentration, polymer thermal degradation, polymer injection duration, and polymer-rock properties (adsorption, residual resistance factor, etc.). The impact of each parameter to oil recovery response was sensitized with its low, mid, and high values. The difference of high to low oil recovery output for all parameters was ranked to determine their significance levels. The top three parameters obtained from the sensitivity analysis are polymer injection duration, thermal degradation, and polymer concentration. Sensitivity cases of polymer injectivity and thermal degradation effects were covered in this work.
The second stage is to determine optimum design parameters of polymer flooding. The most significant parameters from the sensitivity analysis results were considered for further optimization. Three parameters that were selected for design optimization include polymer injection duration, polymer concentration, and well spacing. An optimization workflow with simplex algorithm is linked with a reservoir simulator to generate optimization cases by varying values of optimized parameters. The optimization iteration stops when the maximum value of the objective function, which is the net revenue, is reached. The optimization cycle was done for rock permeability of 500 md and 1000 md.
For a low rock permeability reservoir, the well spacing should be short and a lower polymer concentration is sufficient to provide a good response, in addition to avoiding potential injectivity problem. There should be minimum injectivity problem for reservoir with permeability above 1000 md. It is very important to apply polymer thermal degradation in the simulation model to avoid an optimistic performance prediction. The sensitivity analysis results provide a good understanding on the significance impact of parameters controlling polymer injection response and potential challenges. The optimization approach used in the study aids in investigating many optimization scenario within a short period of time.
Siv Marie Åsen, UiS, IRIS, and The National IOR Centre of Norway; Arne Stavland and Daniel Strand, IRIS; and Aksel Hiorth, UiS, IRIS, and The National IOR Centre of Norway Summary In this work, we examine the common understanding that mechanical degradation of polymers takes place at the rock surface or within the first few millimeters of the rock. The effect of core length on mechanical degradation of synthetic enhanced-oil-recovery (EOR) polymers was investigated. We constructed a novel experimental setup for studying mechanical degradation at different flow velocities as a function of distances traveled. The setup enabled us to evaluate degradation in serial mounted core segments of 3, 5, 8, and 13 cm individually or combined. By recycling, we could also evaluate degradation at effective distances up to 20 m. Experiments were performed with two different polymers [high-molecular-weight (MW) hydrolyzed polyacrylamide (HPAM) and low-MW acrylamide tertiary butyl sulfonic acid (ATBS)] in two different brines [0.5% NaCl and synthetic seawater (SSW)]. In the linear flow at high shear rates, we observed a decline in degradation rate with distance traveled. Even after 20 m, some degradation occurred. However, the observed degradation was associated with high pressure gradients of 100 bar/m, which at field scale is not realistic. It is possible that oxidative degradation played a significant role during our experiments, where the polymer was cycled many times through a core.
A bulk of near-term output will come domestically, but the subsidiary of state-owned China National Offshore Oil Corporation is leaning on its international projects to boost production longer-term. The company said it expects to produce 1.33 million BOE/D in 2019, an increase of 2% from its 2018 average, with domestic output accounting for 67% of this year’s production. The ExxonMobil-operated Guyana consortium has tallied 10 discoveries to date. CNOOC expects six new projects to come on stream this year. The four other projects are the Shell-operated Appomattox project in the US gulf and CNOOC’s Bozhong 34-9 oil field, Caofeidian 11-1/11-6 comprehensive adjustment project, and Wenchang 13-2 comprehensive adjustment project off China.