Evaluation of an alkali-polymer flooding technique for enhanced oil recovery in Trinidad and Tobago

Abstract Trinidad and Tobago (TT) is seeking to develop more economical methods of enhanced oil recovery to arrest the decline in crude oil production and to meet the current and future energy demand. The utilization of alkaline-polymer flooding to enhance oil recovery in TT requires key studies to be conducted to obtain critical information of the flooding system (soil type, additive type, pH, adsorption characteristics and rheological (flow) characteristics). Understanding the role of, interplay and optimizing of these variables will provide key input data for the required simulations to produce near realistic projections of the required EOR efficiencies. The parameters of various wells in TT were compared to the screening criteria for alkali-polymer flooding, and the EOR 4 well was found to be suitable and thus selected for evaluation. Laboratory adsorption studies showed that the 1000 ppm xanthan gum flooding solution containing 0.25% NaOH exhibited the lowest absorption capacity for the gravel packed sand and exhibited the lowest viscosity at all the tested shear rates. The lowest adsorption was 2.27 × 10−7 lbmole/ft3 which occurred with the 1000 ppm xanthan gum polymer containing 0.25% NaOH, and the evidence showed that the polymer was adsorbed on the other side of the faults, indicating that it has moved further and closer to the producing well. Implementation of an alkali polymer flooding resulted in an incremental increase in the recovery factors (~ 3%) compared to polymer flooding; however, a change in the oil recovery as a function of the alkaline concentration was not observed. The simulated economic analysis clearly shows that all the analysed EOR scenarios resulted in economically feasible outcomes of net present value (NPV), Internal Rate of Return (IRR) and payback period for oil price variations between $35 and $60 USD per barrel of oil. A comparison of the individual strategies shows that the alkali-polymer flood system utilizing 0.25% sodium hydroxide with 1000 ppm xanthan gum is the best option in terms of cumulative production, recovery factor, NPV, IRR and time to payback.

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An evaluation of the enhanced oil recovery potential of the xanthan gum and aquagel in a heavy oil reservoir in Trinidad

Journal of Petroleum Exploration and Production Technology ◽

10.1007/s13202-020-00878-5 ◽

2020 ◽

Vol 10 (8) ◽

pp. 3779-3789 ◽

Cited By ~ 3

Author(s):

Tina Coolman ◽

David Alexander ◽

Rean Maharaj ◽

Mohammad Soroush

Keyword(s):

Trinidad And Tobago ◽

Adsorption Capacity ◽

Enhanced Oil Recovery ◽

Oil Recovery ◽

Xanthan Gum ◽

Polymer Solutions ◽

Concentration Level ◽

Polymer Flooding ◽

Soil Types ◽

Polymer Flood

Abstract The economy of Trinidad and Tobago which mainly relies on its energy sector is facing significant challenges due to declining crude oil production in a low commodity price environment. The need for enhanced oil recovery (EOR) methods to meet the current and future energy demands is urgent. Studies on the use of polymer flooding in Trinidad and Tobago are limited, especially in terms of necessary data concerning the characterization of the adsorption of polymer flooding chemicals such as xanthan gum and aquagel polymers on different soil types in Trinidad and the viscosity characteristics of the polymer flooding solutions which affect the key attributes of displacement and sweep efficiency that are needed to predict recovery efficiency and the potential use of these flooding agents in a particular well. Adsorption and viscosity experiments were conducted using xanthan gum and aquagel on three different soil types, namely sand, Valencia clay (high iron) and Longdenville clay (low iron). Xanthan gum exhibited the lowest adsorption capacity for Valencia clay but absorbed most on sand at concentrations above 1000 ppm and Longdenville clay below 1000 ppm. At concentrations below 250 ppm, all three soil-type absorbent materials exhibited similar adsorption capacities. Aquagel was more significantly absorbed on the three soil types compared to xanthan gum. The lowest adsorption capacity was observed for Valencia clay at concentration levels above 500 ppm; however, the clay had the highest adsorption capacity below this level. Sand had the highest adsorption capacity for aquagel at concentrations above 500 ppm while Longdenville clay was the lowest absorbent above 500 ppm. Generally, all three soil types had a similar adsorption capacity for xanthan gum at a concentration level of 250 ppm and for aquagel at a concentration level of 500 ppm. The results offered conclusive evidence demonstrating the importance that the pore structure characteristics of soil that may be present in oil wells on its adsorption characteristics and efficiency. Xanthan gum polymer concentration of 2000 ppm, 1000 ppm and 250 ppm showed viscosities of 125 cp, 63 cp and 42 cp, respectively. Aquagel polymer concentrations of 2000 ppm, 1000 ppm and 250 ppm showed viscosities of 63 cp, 42 cp and 21 cp, respectively. Aquagel polymer solutions were found to generally have lower viscosities than the xanthan gum polymer solutions at the same concentration. Adsorption and viscosity data for the xanthan gum and aquagel polymers were incorporated within CMG numerical simulation models to determine the technical feasibility of implementing a polymer flood in the selected EOR 44 located in the Oropouche field in the southwest peninsula of the island of Trinidad. Overall, aquagel polymer flood resulted in a higher oil recovery of 0.06 STB compared to the xanthan gum polymer flood, so the better EOR method would be aquagel polymer flood. Additionally, both cases of polymer flooding resulted in higher levels of oil recovery compared to CO2 injection and waterflooding and therefore polymer flooding will have greater impact on the EOR 44 well oil recovery.

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Evaluation of a low salinity water flooding with polymer gel treatment in Trinidad and Tobago

Journal of Petroleum Exploration and Production Technology ◽

10.1007/s13202-020-00991-5 ◽

2020 ◽

Vol 10 (8) ◽

pp. 3971-3981

Author(s):

Sanyah Ramkissoon ◽

David Alexander ◽

Rean Maharaj ◽

Mohammad Soroush

Keyword(s):

Trinidad And Tobago ◽

Oil Recovery ◽

Xanthan Gum ◽

Oil Production ◽

Polymer Flooding ◽

Water Flooding ◽

Caribbean Region ◽

Low Salinity ◽

Low Salinity Water ◽

Salinity Water

Abstract Trinidad and Tobago (TT) has a rich history of crude oil production and is still one of the largest oil- and gas-producing countries in the Caribbean region. The energy sector contributes approximately 35% of GDP to its economy; however, economic headwinds due to steadily decreasing oil production, low commodity prices and increased competition worldwide have highlighted the need for more economical methods of enhanced oil recovery (EOR) techniques. Although the use of low salinity polymer flooding for EOR has had success in other countries, critical information relating associated flooding system parameters such as soil type, additive type, adsorption characteristics, rheological (flow) characteristics, pH and salinity is not available and is critical if this type of EOR is to be implemented in TT. The nature and inter-relationship of these parameters are unique to a particular reservoir, and studies in this regard will provide key input data for simulations to produce near realistic projections of this EOR strategy. These projections can be used to evaluate the usefulness of a low salinity polymer flooding in TT and guide for the proper implementation of the strategy. The EOR 33 wells located in the lower Forest sands in Southern Trinidad was selected for study as they satisfied the screening criteria. Laboratory studies of the adsorption of xanthan gum concentrations of 0 to 4000 ppm in combination with NaCl solutions (0–40,000 ppm) onto gravel packed sand found that the mixture of 1000 ppm polymer containing 1000 ppm NaCl exhibited the lowest adsorption capacity. The Langmuir coefficients were derived for each salinity, and together with results from the viscosity studies were inputted within the simulation models. Simulations of a sector of the EOR 33 projected that the highest oil recovery occurred using NaCl < 2000 ppm was 11% greater than water flood. A combination of brine (NaCl < 2000 ppm) with gel technology (1000 ppm polymer) produced the highest oil recovery factor (54%), almost twice that of water flooding, the highest average reservoir pressure and lowest water cut value. The improved performance characteristics observed using low salinity water flood with xanthan gum gel for injection can be associated with improved displacement efficiency and improved the sweep efficiency suggesting the strategy to be a technically feasible option for the EOR well in Trinidad.

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Potential of using chemical enhanced oil recovery in the White Tiger field, offshore Vietnam

Science and Technology Development Journal ◽

10.32508/stdj.v17i3.1489 ◽

2014 ◽

Vol 17 (3) ◽

pp. 117-125

Author(s):

Thinh Phu Nguyen ◽

Khanh Quang Do ◽

Quang Trong Hoang ◽

Nguyen Viet Khoi Nguyen

Keyword(s):

Enhanced Oil Recovery ◽

Oil Recovery ◽

Energy Demand ◽

Petroleum Reservoirs ◽

Chemical Flooding ◽

Screening Criteria ◽

Chemical Eor ◽

Petroleum Companies ◽

White Tiger ◽

Eor Processes

With growing global energy demand and depleting reserves, enhanced oil recovery (EOR) from existing or brown fields has become more and more necessary and important. Among the various enhanced oil recovery methods, chemical EOR has drawn increasing interest from many petroleum companies. In this paper, the popular EOR methods are introduced briefly. Next, we also consider the EOR processes of chemical flooding and the screening criteria for chemical EOR processes in detail. Finally, based on the data of the White Tiger (Bach Ho) field, we evaluate and predict the potential of using chemical EOR at the main different petroleum reservoirs from the Miocene, Oligocene to fractured basement formations.

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