Qatar Foundation Annual Research Forum Volume 2013 Issue 1

Context and objectives The dominant majority of the oil and gas reservoirs in the Middle East and in Qatar in particular are composed of carbonate porous media. Therefore, a better description of the heterogeneous carbonate porous media is a key challenge that will ultimately lead to efficiently unlock and develop new reserves. One of the main characteristics of carbonate rocks is their high reactivity in contact with hydrochloric acids. Therefore, matrix acidizing producer wells in carbonate formations is a common operational practice that helps to increase the permeability of the damaged or tight near wellbore region. One of the main objectives of matrix acid stimulation is to achieve a good zonal coverage with the acid, especially to stimulate hydrocarbon production from low permeability zones, especially in the presence of high permeability contrasts. However, field applications show that matrix acid stimulation leads often to an insufficient increase of permeability in the targeted region as well as an increase in water production from watered zones. Solution In this context, Qatar Petroleum and TOTAL are jointly investigating improved acid stimulation methodologies in carbonates. Within our testing facilities at Qatar Science and Technology Park (a member of the Qatar Foundation) and in liaison with TOTAL's research headquarters in France, we performed high pressure and temperature single and dual core flooding experiments over a range of four different carbonate rocks with different permeability and pore structures. Results Live and emulsified acids were used as well as Relative Permeability Modifiers (RPMs) and particle-laden diverters. Changes in permeability were measured in real time during the injection across the length of the cores. In addition, pre and post-injection micro-CT scanning allowed the visualization of different dissolution patterns (mainly dominant worm-holing). Changes in porosity induced by the chemical reactions were also deduced based on image analysis. We compared the response of different acid types and assess the impact of RPMs on brine and oil flow. Conclusions The test results will serve as a basis for elaborating new acid pumping sequences for well stimulation an also to benchmark different commercial and academic acid stimulation software. The results can be used to different applications such as carbon storage in heterogeneous carbonates.

Owning to the awareness of the correlation between fossil fuel consumption and the ongoing climate changes, there is general acceptance that deploying more renewable energy resources is an urgent issue. Recently, geothermal power plant has been introduced as a smart solution to reduce fossil fuel consumption. Unlike other renewable energy resources, the available energy of geothermal energy is constant all year long. Geothermal refers to existing heat energy in deep rock and sedimentary basins. This energy can be used to drive a power turbine to generate electricity. The depth and temperature of hot rock remain the major obstacles to the commercial viability of enhanced geothermal energy. The fact that such energy is only available at high depth creates technical and economic problems. From an economic viewpoint, the high initial capital cost of geothermal power plants is the main barrier to commerciality of geothermal energy. Exploration and drilling of wells account for up to 40% of the total cost of the project. On the other side, oil wells are drilled to the depth where the temperature could be higher than 100 C. Since organic Rankine cycles (ORC) can operate between smaller temperature difference, harvesting energy from a low temperature source such as oil wells is possible. Thus, utilizing these wells means a significant part of initial capital cost of geothermal power plants can be eliminated. This way the economic viability of geothermal power plant becomes bigger. The current study presents thermodynamic and economic analyses of a binary geothermal power generation system for commercial electricity generation in Qatar. The optimal working fluid and optimal design at working conditions of Qatar are defined. The levelized cost of electricity and the payback period of geothermal POWER plant will be calculated for optimal working design.

The ability of date palm (Phoenix dactylifers L.) to grow in hot and dry regions of the world makes it an important subsistence crop in most arid areas. Nevertheless, salinity and drought are the main abiotic stresses causing loss of date palm yield. Here we employed the next generation sequencing technology for high-throughput sequencing of date palm transcripts in response to salinity. cDNA libraries, from roots treated with 100 mM Sodium Chloride and mock treated roots, were sequenced via Illumina HiSeq2000 system. Data analysis identified 1940 genes that are differentially expressed between treated and mock treated roots. MYB transcription factors, protein kinase, E3 ubiquitin ligase, calmodulin, polyamine oxidase and acetyltransferase transcripts are regulated in response to salinity stress suggesting potential roles of these genes in tolerance to salinity stress. Additionally, we examined the cellular responses of date palm tissue to salinity stress using transmission electron microscopy (TEM). Results from TEM show that stressed roots exhibited plasmolysis in cortical cells while epidermal cells did not appear to plasmolyze. Columnar cells in the distal root region might form a barrier to salt intrusion, which would make the older regions of the root less susceptible to salt plasmolysis. Output from this project will help in enhancing our understanding of date palm signaling mechanisms and developing new strategies to control salinity stress.

Rising global energy demand and advancements in subsea engineering technology has made subsea oil and gas systems the dominant source for energy. The critical challenges in subsea systems included the associated external pressures and cold temperatures in ultra-deep water. Both of these challenges directly influence the safety and production of subsea oil and gas. Specifically, the design of a subsea pipeline must not only provide the structural integrity to withstand high external pressures but must be durable with respect to corrosion, and guarantee the flow of hydrocarbons. The latter two issues can only be investigated using temperature models that capture the heat transfer from the oil/gas mixture, through the pipeline and to the seawater. To predict temperatures along a pipeline during shutdown, software tools are available which provide numerical solutions based on the solution of mass, momentum and energy conservation equations. However, due to the complexity of these equations, it takes hours to generate results with no clear indication that the resulting simulations are correct. The objective of this project is to develop a low dimensional model that can accurately predict temperatures along pipelines during offshore oil production system shutdown. To develop the model, energy conservation of the fluid within the pipeline is considered. To solve this energy conservation equation, analytical and numerical methods, centered upon lumped capacitance method and finite difference method, are explored. These results are then compared with the developed low dimensional model. The low dimensional model is based on a modified finite difference method used for the energy conservation equation solution, which is integrated with a one dimensional heat conduction equation along a hollow composite cylinder. Steady state temperature profiles are also explored in order to generate the initial conditions for this modified finite difference method. Furthermore, the accuracy of this model is verified by comparing with the results generated by commercial software. The accuracy of this model could be further increased by using a finer mesh for which temperatures are to be determined. However, this would increase its computation time.

The southeastern, leeward coast of Qatar presents a unique example of arid shoreline sedimentation patterns dominated by sand dune fields blown into the sea. The observed sediment dynamics, geospatial data, and facies patterns are analogous to aeolian reservoir systems in ancient rocks, like the Permo-Carboniferous Unayzah Formation of the Middle East or the Permian Rotliegend Formation of Northwest Europe. Oldest sediments exposed along the coastal plain are relicts of a Holocene sea-level highstand of approximately 2 to 4 meters above present day sea level. Oldest radiocarbon age dates reveal marine beaches and lagoonal deposits began forming 4000-6000 years before present. Unlike most coastal depositional systems, the beaches are sourced from onshore, aeolian sand dunes. The coast has prograded 5 to 10 kilometers during the Holocene. The Khor Al-Adid coast is subdivided into two, very distinct sedimentological provinces. The northern part of the coast is linear, reflecting a continuous source of aeolian sand. Back shore areas are only flooded seasonally. The southern coast is deeply embayed into a mosaic of restricted lagoons where stromatolites and evaporite flats are widespread. The embayment occurs in the shadow of the bedrock topographic highs that have diverted the aeolian sand supply to the coast. Most coastal plain is covered by 5 to 10 meters in relief (max 60 meters) dunes. In spite of their height and size, dunes are an ephemeral feature of the landscape. Only the basal 1 to 2 meters of a dune are preserved, where trapped by cementation in shallow, standing waters (lagoons, interdune floods). Lightly cemented erosional remnants of dune toesets are composed of unidirectional cross-bedded, tabular foresets with flat tops. They extend up to several kilometers, passing laterally in parallel and wavy laminated gypsum cemented sand. The embayed, southern area has a fairly uniform facies pattern, marked by shallow mesohaline lagoons separated from the open sea by ebb and flood deltas. The leeward side of the lagoon is marked by intertidal stromatolites. Remnants of former dunes form barriers, separating mesohaline from hypersaline lagoons. Hypersaline lagoons are marked by subtidal stromatolites that alternate with gypsum mush and rarely, salt flats. Some evaporite flats are relicts from previously active back barrier lagoons. Khor Al-Adaid sedimentation patterns reflect the interplay between sea level, physical and chemical depositional processes, and aeolian deflation. Understanding the interplay between these factors provides the basis for building more realistic geological models.

Surveying biodiversity is a very expensive and time consuming work particularly in the marine environment. This is why we have to find practical and efficient solutions to identify the species and their habitats in order to proceed with management and conservation plans. Very little information is available for marine snakes' biodiversity in the Gulf region, but particularly for Qatar where no biodiversity studies have been conducted to date. We have explored the presence of marine snakes in Qatar based on public information obtained from interviews done to people living in Qatar. We have interviewed 655 persons during January to May 2013 in different zones and ports of the State of Qatar, and from different countries, social sector, age and period of time living in Qatar. Most interviewed people were adults originally from 36 different countries; however, the majority was from India, Qatar and Nepal. Most of them were based in Qatar for only 1-2 years, while the rest were living in Qatar from few months to all their life. Only 16% of the persons interviewed (n= 102) have seen snakes in Qatar. Some snakes were observed near the Qatar coast and ports but most of them were seen offshore (89% of the observations). We have explored the potential diversity of marine snakes present in Qatar by showing to the interviewed persons a form with photos of 10 different species that have been reported to exist in Qatar. Most people have seen only one snake species, while two different species were seen by 25 persons and 3 species by 15 persons. The maximum number of marine snakes seen by the people has been four, and only 2% of the persons saw them. The snakes more frequently seen have been Lapemis curtus (18% of the observations), Leioselasma cyanocincta (13%) and Leioselasma spiralis (12%). In this study we have also examined if the probability to see a marine snake by the people is related to different variables, including the social sector (fisherman, sport clubs, general public), the study area (8 zones), the number of years living in Qatar, the age of the person (adult or young) and their nationality. The results have shown that most observations of sea snakes have been conducted offshore at traditional fishing areas around islands, while coastal records are limited to mangroves, ports and marinas. Most observations have been conducted by fisherman from India, by Qatari citizens working at the university and the Ministry of the Environment and by experts working in the environmental departments linked to petrol companies in Qatar. This abstract is a contribution for the Qatar Foundation Annual Research Conference (QF-ARC-2013).

Wettability of a carbonate reservoir is one of the key points concerning oil recovery. Most carbonate reservoirs tend to be oil-wet. An oil-wet wettability generates significant problems in oil recovery since the formation has a stronger ability to keep oil attached in its pores, and it also decreases the efficiency of water flooding leading to faster water breakthrough. Wettability alteration in oil wet carbonate reservoirs have demonstrated to be a successful method in enhancing oil recovery through chemical water flooding of such formations. Wettability, IFT (Interfacial tension), and temperature, are all parameters that have a significant effect on the recovery process. Different processes and chemicals have been tested to study the alteration of wettability through contact angle and its effect on oil recovery. It is essential to understand the correlation between the IFT value of the brine injected with the degree of wettability alteration, in order to assemble an optimized brine solution for enhancing oil recovery by finding an optimized contact angle and an IFT value. In this paper, carbonate outcrop samples from Jabal Fuwayrit in Qatar (considered to be a similar and representative to the North Field formation) were used to make a comparative study of wettability alteration effect followed by recovery. Spontaneous imbibition and flooding of brine with different chemical composition were employed. We also studied the effect of non-ionic and cationic surfactants in sea water from Qatar to further enhance oil recovery. Comparison of the results obtained leads to a better understanding of wettability alteration and the appropriate selection of injection brine for optimal recovery. The significance of such study can be easily demonstrated. Wettability understanding and alteration at will is of a great importance and can be expanded in all type of reservoirs, giving a cost-effective, fast and functional process.

Petroleum wells that cease to produce oil/gas economically and dry holes are referred to as abandoned wells. An abandoned well is usually plugged with cement and can take anywhere from two days up to a few weeks to cure depending on the number of plugs in the well. Since plugging a well costs capital, most wells are abandoned at the lowest possible cost and with the minimum obligations set by regulation agencies. These wells can present enduring liabilities to petroleum companies and/or governments. However, the depth and abundance of abandoned petroleum wells make them an economically attractive source of geothermal energy. Geothermal energy harvested from an oil/gas well is a renewable energy source as long as it is extracted in a sustainable manner. The energy can be used to generate electricity, used directly for heating, incorporated into a water desalination process, or used by a heat pump for heating/cooling applications. In this paper we examine the possibility of extracting geothermal energy from abandoned oil/gas wells by studying the heat transfer in underground geothermal heat exchangers installed in these wells. A double-pipe (shell and tube) design configuration is chosen for the geothermal heat exchangers embedded inside a petroleum borehole. Using in-situ gathered information from some representative petroleum boreholes in the Gulf region, the effects of key parameters such as geothermal gradient, ground temperature values, and the flow inside of the tubes are evaluated. In order to provide a constant power production the inlet temperature it is proposed to adjust the temperature of the inlet fluid, so that that the difference between outlet and inlet temperatures is kept at a desirable value. Higher differences between inflow and outflow temperatures will result in a less sustainable load put on the in-situ geothermal energy. Adding insulation to certain sections of the designs can minimize the transfer of thermal energy from the fluid to the surroundings. Insulation can also limit the thermal loss between the inflow and outflow tubes in the shell and tube design. Minimizing the energy loss of these designs leads to an increase in the outlet temperature, meaning a higher grade of heat. The sustainability of long term geothermal heat extraction is a balance between the rate at which geothermal energy is extracted and the rate at which the ground formation can replace this heat. Higher outlet temperatures can lead to a larger amount of power generation, and a higher coefficient of performance for heat pump applications. It is found that Qatar's abandoned petroleum wells can be economically reused for the purpose of sustainable geothermal energy production.

Date palm roots, like roots of other plants, host many microorganisms including bacteria and fungi. These microbial communities can have both favorable and unfavorable effects on the date palm's health and production. For this reason, the effect of the nitrogen source in the fertilizer on microbial communities and metabolomics is being studied. In this project we will use state-of-the-art metagenomic approaches to analyze the microbial communities present in the rhizosphere under different fertilization regimes. Also the effect of the roots of different cultivars on the microbial diversity will be addressed. The metabolomic analysis will be carried out by another research team. An experiment is being carried out at the Roudat Alfars Research Farm of the Ministry of Environment. Four different fertilization regimes were applied in which the nitrogen sources were either mineral or organic in three replications (3 palms) on cultivar Khalas. Three more cultivars were used to examine the cultivar's effect on rhizosphere microbial communities. The evaluation of the effect of the nitrogen source on the microbial diversity in the rhizosphere will be carried out for one year. The first samples (roots and soil) were collected for metagenomic analysis. Sampling will be carried out every three months. Palms were also genotyped using 23 microsatellite primers for confirmation of their identity. Results showed no differences in genotyping between the 12 Khalas palms used. Four protocols for DNA extraction for metagenomic analysis are being tested. The most suitable protocol will be standardized to extract the DNA from all samples. Different primers for PCR reactions and high-throughput DNA sequencing will be used in the coming year for microbial identification. They will also be used to find microorganisms with potential for agricultural practice such as nitrogen and phosphorus fixation, and antimicrobial and pesticidal effects.