Environmental pollution is one of the major consequences of gas flaring. In the rural oil producing communities of the Niger Delta where this age long practice is common and a large portion of the population use rain water for domestic activities, it is imperative to evaluate the rain water quality in these environments. In this work, a hundred samples of rain water were collected within a period of two years from a typical community where gas flaring has been dominant for several decades. The samples were analyzed in the laboratory for pH value, turbidity and nitrite content, and the results were compared against the World Health Organization (WHO) standard for water quality. The study shows that the rainwater samples collected from the gas flaring zone had an average turbidity value of 22.58NTU, an average pH value of 6.75 and contained an average of 2.6mg/l of nitrite. However, when considered separately, some rain water samples met the WHO standard while others did not. It was observed that about 61% of the samples considered met the WHO standard on turbidity of 15NTU for rain water and 17% of the samples met the standard for drinking water which is 5NTU. 26% met the lower pH standard of 7.0 for drinking water while 64% met the pH standard of 6.5 for rain water. 60% met the WHO requirement for nitrite content of 3mg/l but generally, about 39% of the samples did not meet the WHO standard for rain water quality. These test parameters indicate that the level of rain water pollution in this gas flaring environment is high and unhealthy especially for the ecosystem system. Thus, drastic measures need to be taken to stall gas flaring in the Niger Delta.
Reservoir souring which occurs due to an increase in hydrogen sulfide (H2S) concentration of a production well stream fluid undergoing water injection for example during secondary recovery, can significantly impact on the economic viability of a deep water project. Souring also raises technical concerns ranging from compromising safety compliance to damaging of infrastructure integrity due to corrosion attack. The activities of Sulfur Reducing Bacteria (SRB) present downhole act on sulfate in the injected water (sea water) to enhance the reproduction and generation of hydrogen sulfide which sours the reservoir. In this work, experimental study was carried out in an XYZ field in the Niger Delta, to evaluate the souring potential of the reservoirs undergoing water flooding. Field test kits were used to determine the temperature, pH and salinity of produced water samples; while colorimetric method was used in the laboratory to determine the sulfate concentration. The strength of stained tubes was used to determine the hydrogen sulfide concentration in the gas phase. The concentration of H2S in one of the wells was as high as 140ppm in the gaseous phase, the salinity concentration ranged between 16,435–24,479mg/l, the sulfate concentration ranged from 0-2200mg/l while the temperature ranged between 31.6°C-62.4°C. The results of the study show a favourable disposition for SRB to thrive and multiply. Also, the reservoirs within the field show different degrees of souring. The outcome of this analysis will be used for proffering cost effective and efficient remedial action.
Reservoir souring most times occurs during secondary recovery, after water injection using seawater or produced water from a different reservoir. Water compatibility studies is thus necessary prior to injection to detect potential for souring and to implement preventive measures since souring poses challenges during production. This work stresses the importance of fluid compatibility studies before undertaking water injection projects. Two cases were considered; in the first case, water injection program was implemented using seawater without conducting fluid compatibility studies and serious souring problem was encountered later in the life of the reservoir. In the second case, fluid compatibility study was conducted where produced water from four sources were proposed to be used for water injection in two reservoirs. One reservoir (RW1) had high sulphate content of 20mg/l but did not have Sulfate Reducing Bacteria (SRB) probably because the reservoir temperature was 103 o C, well above the limit for the existence of most SRB. The second reservoir (RW2) with a temperature of 75 o C had SRB concentration of 845cfu/ml and had a sulfate concentration of less than 0.01mg/l, indicating that souring will only occur if water containing sulfate is injected into it. The study shows that reservoir souring could occur in both reservoirs from external sources. It was concluded that three out of the four proposed produced water cannot be injected into RW1 without treatment since their water samples contain SRB. Reservoir souring and its associated problems were thus prevented from occurring in RW1 due to fluid compatibility studies.
Production of formation water during petroleum exploitation is sometimes inevitable, necessitating disposal strategies. Produced formation water can be re-injected back into the reservoir either for enhanced oil recovery schemes or for the purpose of disposal. In any case, there is a need to prevent scale formation because it leads to permeability impairment. In this work, formation water compatibility tests were conducted to detect scaling potentials using the Langelier Saturation Index (LSI). Six water samples were used; four produced water samples intended for use in water injection schemes and two water samples obtained from reservoirs needing water injection programs. The water composition of scale-forming elements such as barium, strontium and calcium were determined for all the samples. Other determined parameters included pH values, total dissolved solids (TDS) and LSI. The LSI for different ratios of produced and reservoir water mixtures were determined. Laboratory results indicated that all the water samples contained scale-forming elements and compounds, and they all had to scale potential at ambient temperature but especially at higher temperatures. The produced formation waters were incompatible with the reservoir waters in terms of their scale-forming tendency. To prevent scale formation, especially at higher temperatures, it was recommended that scale inhibitors be used with the least scale-forming produced water. It was also recommended that produced formation waters be subjected to fluid compatibility studies before use in water injection schemes to prevent scale formation.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.