Niger Delta Oil Field Research Articles

Niger Delta Oilfields Produced Water Characteristics and Treatment Technologies: Challenges and Solutions

The Nigerian Niger Delta oilfields have high water-to-oil ratio ranging from 50% to 95% water content, due to its secondary and tertiary production phases. Oil and gas producers could shut-in such wells, or develop cost effective approach for Produced Water, PW handling to meet reinjection or environmental permissibility. Thus, the study investigated the compositions and treatment techniques of Niger Delta oil and gas fields PW, and proffered solutions for actualizing minimal hazardous contaminants in PW. Characterization of PW from a Flow Station, an Oil processing and a Gas processing facilities showed biogeochemical homogeneity in the PW compositions with high organic and inorganic constituents, which are above injection and disposal specifications. The results of treated PW from the extant PW treatment (PWT) techniques showed that the total dissolved solids (TDS) concentration (6105.9 mg/l) from the Flow Station PW treatment facility did not meet the required specifications for injection into depleted wells or disposal into the environment (2,000.00 mg/l for inland, and 5,000.00 mg/l for nearshore). The salinity contents in the treated PW from the three PWT configurations were 2411.0 mg/l, 2218.6 mg/l, and 2165.4 mg/l, respectively, which were slightly above Nigerian Upstream Petroleum Regulatory Commission (NUPRC) specification (2000.0 mg/l) for nearshore disposal. The chemical oxygen demand (COD) concentration in the treated PW from the three PWT configurations were 153.0 mg/l, 148.1 mg/l, and 141.2 mg/l, respectively, which were above the NUPRC standard (125.0 mg/l). The oil and grease (O&G) concentration in the treated PW were 84.7 mg/l, 51.5 mg/l, and 58.0 mg/l, respectively, which also were above regulatory stipulation (30.0 mg/l) for nearshore disposal. The modular Bio-Unit + Ultra/Nanofiltration achieved more than 95% removal of both organic and inorganic constituents in the PW. Therefore, this study suggests that reconfiguring the extant PW treatment equipment with this cost-effective innovation would be the solution to PW treatment challenges in the Niger Delta oil and gas operations.

Multicriteria evaluations for sand production potentials: a case study from a producing oil field in the Niger Delta Basin (Nigeria)

Geomechanical evaluation of three wells in an onshore Niger Delta Oil Field in which some reservoirs have histories of free water production was carried out to predict their potential for sand production. The mechanical characteristics of the reservoirs, such as the Poisson ratio (v), shear modulus (G), elastic modulus (E), bulk modulus (Kb), and bulk compressibility, were calculated using petrophysical parameters such as s-velocity (Vs), p-velocity (Vp), gamma ray index (IGR), the volume of shale (Vsh), porosity (), and pseudo factor (q) derived from wireline logs (Cb). Five geomechanical techniques—porosity, acoustic wave travel time, sand production index, Schlumberger sand production index, and shear modulus to bulk compressibility ratio (G/Cb) were used to forecast the potential for sand production in the reservoirs. The porosity values varied from 14 to 27%, which is below the threshold value of 30% for sand production. The acoustic wave travel time ranged from 81.59 to 89.91s/ft, which is below the threshold value of 104s/ft for sand production. The threshold value for the sand production index was < 2.9 ×106psi. The values for the sand production index fell between 11x 106psi and 12.4 x 106psi, which is below the limits for the onset of sanding. The G/Cb values in the reservoirs across the three wells fell between 1.15 x 1012psi2 and 1.43 x 1012psi2 while the threshold value for the Schlumberger sand production index fell between 1.15 x 1012psi2 and 1.43 x 1012psi2. Only the Schlumberger criterion predicted the potential for likely sand production.

Treatment of Produced Water from Niger Delta Oil Fields Using Selected Bio-Adsorbents

Produced water (PW) is the vast amount of water produced from subsurface during the extraction of oil and gas. PW contains heavy metals which are detrimental to the environment. The majority of PW treatment technologies, which have been in use for many years, have reportedly failed to bring some impurity and metal concentrations down to permissible disposal levels. This study was done to determine how well three locally available materials which are eggshells, groundnut shells, and sugarcane bagasse used in the treatment of PW obtained from Niger Delta oil fields. The adsorbents were ground, and sieved into sizes of 425 and 1180 microns. They were treated individually with diluted nitric acid (400mL of 0.4mol/ LHNO<sub>3</sub>) for 24 hours to remove pigments. They were filtered, dried, and rinsed with distilled water until the pH became neutral. PW samples were analysed for heavy metals using an Atomic Absorption Spectrophotometer (AAS). The PW samples were treated with the bio-adsorbents in a batch technique. The metals analysed were As, Cu, Pb and Fe. The bioadsorbents were able to reduce the concentration of the metals to 87%, 91%, 100% and 88% respectively. Langmuir and Freundlich isotherm models were used to analyse the adsorption system. It was observed that the finer the adsorbents the better the adsorption result. 425 microns was able to produce a better result compared with 1180 microns.

Removal of Heavy Metals from Produced Water Using Activated Carbon from Coconut Husk Enhanced with Graphene Oxide

Produced water, which contains a high amount of hydrocarbons, heavy metals, and other pollutants, is one of the major waste streams in the Niger Delta's oilfields and refineries. The treatment of produced water can be done in a variety of ways, including physical (desalination, membrane separation and, adsorption), chemical (precipitation, absorption and, oxidation), and biological. The heavy metals and contaminants in the wastewater pose a threat to living creatures and the environment. This research evaluates the effectiveness of Activated carbon modified with Graphene oxide, a new thriving material for researchers derived from graphite, to improve the adsorption capacity of coconut husk using the “wet impregnation technique” for the removal of heavy metals from produced water. Batch adsorption of the pollutant was studied for the Activated Carbon, and the modified activated carbon (AC-GO) at a time intervals, for each of the adsorbents. The removal efficiency of the adsorbent was found to increase proportionately from 6.71% to 92.96%, 3.01% to 52.23% and 51.28% to 67.77% for Cd, Ni and Pb respectively with increasing contact time. Atomic absorption spectroscopy (AAS) analysed the treated produced water samples. The adsorption isotherms and kinetics studies of the adsorbed metals were evaluated and correlated with empirical models.

Marginal Fields Development in Nigeria: A Review of Extant Strategies

This paper focuses on the development of marginal fields in Nigeria, the challenges, economic viability, and the role of the government in implementing the contributions of marginal fields to the national oil production output. Also, the previously reported marginal field development and management practices in the Niger Delta oilfield are x-rayed. Following the definition of the marginal field is an overview of different types of marginal field development in the Niger Delta region. Also, the United Kingdom Oil and Gas Recovery Regulatory Commission, the United States Security Exchange Commission, and the Nigerian government's categorization of what compose of a marginal field are included. In addition, the participation of the Nigerian federal government and contributions to the development of marginal fields in the bidding of marginal assets to the development of infrastructure are presented. Particular attention is paid to the factors that affect the development and choice of production strategies in the marginal fields of the Niger Delta. These factors discussed in detail in the document include environmental, technical, social, political, and economic factors. Again, different management and development strategies used by some marginal fields of the Niger Delta are x-rayed and presented with a particular focus on three of those strategies. The three common approaches in the Niger Delta marginal field development strategy are water flooding, infill drilling, and infrastructure sharing. These approaches have made marginal fields in Nigeria operational, competitive, and economically viable to date.

Analysis of crude oil production with gas lift methods

Some wells in the Niger Delta area are in their late production life. Water production increases with and reservoir pressure decreases to the point that the natural energy cannot sustain the production of hydrocarbon to the surface. The severity of this impact has been observed in the Niger Delta oil fields over the past years that has caused the abandonment of wells with a significant volume of hydrocarbon unrecovered. To increase production and extend the life of these wells, a gas lift project is considered. This study aimed to analyze oil production between continuous and intermittent gas lift systems based on real data obtained from two oil wells in a Niger Delta oilfield and to choose the system best suited to increase the production of the wells. To achieve this aim, a simulation study on continuous and intermittent gas lift methods was conducted using GAP and PROSPER software. The results obtained indicated that a continuous gas lift system will be suitable for a well that has a high flow rate and high GOR (well 1). For Well 2, the results indicated that an intermittent gas lift system will be suitable for a well that has lower reservoir pressure and low productivity.

English

Produced water (PW) during oil and gas production operations contains various hazardous substances including heavy metals (HM) with adverse impact on the environment. Disposal of PW interferes with environmental sustainability, making PW treatment obligatory prior to discharge into the environment. Among previously available treatments of PW, environmentally sustainable methods using low-pore space bio-adsorbents require further development. This study investigated the efficacy of chemically-modified activated carbon (cMAC) of Luffa cylindrica (LC) and Banana Peel (BP) for the treatment of PW obtained from Niger-Delta oilfield, treated (2, 4, and 6 h) with finely ground (425 μm) carbonized LC and BP impregnated separately with phosphoric-acid and sodium hydroxide. The derived cMAC was characterized by proximate analysis and FTIR spectroscopy. Treated PW was analysed for HM using AAS, Langmuir, and Freundlich isotherms. Obtained values of the surface area for the cMAC from LC were 880 (NaOH), 830 (H3PO4) m2/g and BP was 810 (NaOH), and 920 (H3PO4) m2/g. The existence of active functional groups is revealed on the FTIR spectra. Results revealed a substantial drop in HM concentrations (Zn: 30-86%, Cu: 78-88%, Ni: 33-55%, Fe: 17-52%) in PW after treatment with cMAC at varying contact times. All metals (Zn, Cu, Ni) in the treated PW except Fe were below WHO and USEPA guideline limits. Treatment of Niger Delta oilfield PW was effectively improved with acid-modified carbonized L. cylindrica.   Key words: Activated carbon, adsorption, bio-adsorbent, heavy metals, oil-produced water, treatment

Treatment of Contaminated Water from Niger Delta Oil Fields with Carbonized Sisal Fibre Doped with Nanosilica from Ofada Rice Husk

Treatment of Contaminated Water from Niger Delta Oil Fields with Carbonized Sisal Fibre Doped with Nanosilica from Ofada Rice Husk

Physicochemical assessment and treatment of produced water: A case study in Niger delta Nigeria

The most important waste stream created during oil and gas production is oilfield-produced water. When discharged without treatment, it poses a significant risk of pollution of marine ecosystems. While adequate treatment before disposal is acceptable, achieving authorized discharge criteria continues to be a problem for the petroleum sector. This research examined the physicochemical characteristics of produced water at various month intervals before and after treatment. Heavy metal and organic component concentrations in water samples were determined using atomic absorption spectroscopy and gas chromatography. The results indicate that produced water from a certain Niger Delta oilfield contains significant amounts of heavy metals and some organic compounds after treatment. The present laws, as well as the measurement of dispersed oil and grease content, have been in place for a long period of time without considerable change, even though most dangerous components in produced water are dissolved. It is recommendable for the prospective field developers/operators to consider the dissolved components of produced water and consider the economic consequences of adopting tertiary produced water polishing technologies.

Evaluation of Electrical Submersible Pump on Field Production Network Optimization in Niger Delta Oilfield

Complexity arises when trying to maximize oil productions from fields using Electrical Submersible Pumps (ESP). The complexity increases with the increase in the number of reservoirs and wells in a particular field. Individual well’s ESP frequencies have to be constantly updated to ensure optimum oil productions from the field. The choice of the ESP frequency to be used must come from sound engineering decisions which do not come from mere intuition but must be backed up by mathematical models and computer simulations. This study proposes to evaluate field production network optimization on ESP lifted wells using quadratic sequential programming techniques. The optimization approach seeks to determine the ESP frequency for each well that will lead to the maximum field oil production while honouring the field operational constraints. Two reservoirs and five wells were considered. The non-linear optimization problem for the ESP lifted wells in the field was formulated with their boundary conditions. The simulations were performed in Prosper and GAP software. Prosper software was used in building the individual well’s ESP models for the five wells in the field. Individual well’s model in Prosper was exported to GAP and simulations were run in GAP for the field network system. GAP simulations were run in two cases: case 1 comprises ESP simulation without optimization while case 2 comprises ESP simulation with optimization. For case 1, fixed values of ESP frequency were selected for each well and the GAP software calculates the production rates from the wells in the network accruing from the ESP frequencies inputted. For case 2, there was no input ESP frequency as the GAP software was allowed to calculate based on optimization algorithms, the best suitable ESP frequencies for each well in the field that will lead to the maximum total oil production in the field network while honouring the operational constraint imposed on the systems in the field. From the results, it was realized that at the basis of well, the higher the ESP frequency, the higher the well’s production rates. Sensitivities on the effects of separator pressure on production rates show that separator pressures affect the well’s productions rates. A reduction in separator pressure from 200 psig to 80 psig led to a 1.69% increase in field oil rate. Comparison of results for case 1 and case 2 showed that ESP field network simulation with optimization yields had a higher field production rate than ESP field network simulations without optimization. There was an increase in oil rate of 1.16% and 2.66% for constraints 1 and 2 when ESP simulation was done with optimization rather than without optimization. Also, simulation with optimization comes with higher pump efficiency than simulation without optimization.

English

Oil reserves in the Niger Delta have been gradually decreasing due to the increased production. New large field discoveries are scarce, thus there is need to improve on the production from existing reserves. Low salinity surfactant flooding (LSSF) is a potential enhanced oil recovery process to increase oil production in the Niger Delta oil fields. In this study, sodium dodecyl sulphate and ethanol were used as surfactant to study the significance of the surfactants on oil recovery. Sand packs were used as formation sample in the laboratory. This was soaked with oil of 24.36° API and specific gravity of 0.9436. Low salinity water was used as a displacing fluid in the secondary recovery mechanism. However, sodium dodecyl sulphate and ethanol (78% vol.) was introduced into the sand packs. The sodium dodecyl sulphate reduced the interfacial tension as obtained using tensiometer machine. Ethanol was used in the second case as surfactant.  The result of the work shows that sodium dodecyl sulphate had oil recovery of 16.1, 16.9, 19.0 and 19.3% respectively at different surfactant concentrations 0.2, 0.3, 0.35and 0.38% wt. respectively; while ethanol (78% vol.) had oil recovery of 1.5%. The study noted that sodium dodecyl sulphate is a good surfactant for enhanced oil recovery for crude oil with the specified API gravity. In addition, interfacial tension reduction and change in rock wettability were the working mechanisms for the sodium dodecyl sulphate to increases oil recovery from reservoirs. The work showed that sodium dodecyl sulphate maintained low interfacial tension through the flood process. Key word: Sodium dodecyl sulphate, interfacial tension reduction, ethanol, crude oil

Support Vector Machine Model for Predicting Gas Saturated and Undersaturated Crude Oil Viscosity of Niger Delta Oil Reservoir

Oil viscosity is one of the most important physical and thermodynamic property used when considering reservoir simulation, production forecasting and enhanced oil recovery. Traditional experimental procedure is expensive and time consuming while correlations are replete however they are limited in precision, hence need for a new Machine Learning (ML) models to accurately quantify oil viscosity of Niger Delta crude oil.
 This work presents use of ML model to predict gas-saturated and undersaturated oil viscosities. The ML used is the Support Vector Machine (SVM), it is applicable for linear and non-linear problems, the algorithm creates a hyperplane that separates data into two classes. The model was developed using data sets collected from the Niger Delta oil field. The data set was used to train, cross-validate, and test the models for reliability and accuracy. Correlation of Coefficient, Average Absolute Relative Error (AARE) and Root Mean Square Error (RMSE) were used to evaluate the developed model and compared with other correlations.
 Result indicated that SVM model outperformed other empirical models revealing the accuracy and advantage SVM a ML technique over expensive empirical correlations.

Management of Produced Water from Niger Delta Oilfield with Modified Agricultural Waste

Hydrocarbon reservoirs contain produced water as one of its constituents. Produced water most times contains toxic materials and other impurities that affect the ecosystem. Most of the available treatment techniques have not been very effective in reducing some of the contaminants to an acceptable disposal limits.Banana peels was washed with clean water, dried under the sun for three days, and oven-dried at 105±5o C for 3 hours. It was milled, sieved (150 and 300 microns,), and then treated with 0.4mol/L HNO3 , rinsed with clean water to remove any pigment that might interfere with the result. Sample (produced water) was treated in adsorption chamber for 4 hours using 150 micron size of adsorbent. Treatment was repeated with 300 micron size. Treated sample was analyzed and characterized. For the 150 micron size, the percentage reductions for the metals concentration (Pb, Ni, Cd, Cu, Fe, Mg, Cr, Zn, Mn, Ca, Ar, B, Sn, Ba) were found to be 87.18%, 23.08%, 42.86%, 100%, 80.12%, 34.33%, 28.93%, 45.40%, 47.89%, 97.18%, 33.06%, 43.24%, 62.50%, and 44.44% respectively. Similar reductions in same metals with 300 micron size were equally obtained. The finer adsorbent was more effective. Langmuir model best described the adsorption of lead with isotherm R2 of 0.98, while Freundlich described the adsorption of nickel and iron, with isotherms R2 of 0.85 and 0.93 respectively. Produced water from Niger Delta oil field was effectively treated of contaminants using banana peels with 150 micron size produced the best result.

Treatment of produced water from Niger Delta oil fields using sequential mixture of bio-adsorbents

Produced water (PW) exploited from the reservoir alongside oil often contains heavy metals and other impurities that are harmful to man and the environment. Most of the PW treatment technologies that have been in use for years have been reported to be ineffective in reducing some of the impurities and metal concentrations to allowable disposal levels. This study evaluated the effectiveness of four local materials combined for treating PW from Niger Delta oil fields. Orange peels (I), banana peels (II), sponge gourd (Luffa cylindrica) (III) and palm kernel fibers (IV) were washed with distilled water, sun-dried (24 hours) and oven-dried at 105 ± 5°C (3 hours, I and II), 150°C (30 minutes, III) and 80°C (3 hours, IV). They were ground into powder, sieved (150 microns, Group A) and (300 mcicrons, Group B), washed with 0.4 mol/L HNO3, filtered and rinsed with distilled water. Samples of PW were obtained from fields R, X, and Y in the Niger Delta and analyzed for heavy metals using an Atomic Absorption Spectrophotometer (AAS). The PW samples were treated with the bio-adsorbents sequentially in the adsorption column for over 7 hours. Langmuir and Freundlich models were used to evaluate the samples and the Data was analyzed based on regression method. The 150 micron size of sample R, lead (Pb), cadmium (Cd), copper (Cu), and chromium (Cr) were completely (100%) adsorbed from the PW after 8 hours of treatment while other metals (Ni, Fe, Mg, Zn, Mn, Ca, Ar, B, Sn, Ba) were found to be 86.11%, 90.76%, 39.25%, 94.40%, 43.55%, 99.26%, 54.62%, 44.53%, 84.52%, and 47.37%, respectively. while the reduction in 300 micron size were 23.48% for Pb, 80.20% for Ni, 71.42% for Cd, 19.73%, for Cu. 43.65% for Fe, 34.79% for Mg, 12.67% for Cr, 88.8% for Zn, 35.48% for Mn, 98.95% for Ca, 23.01% for Ar, 44.52% for B, 14.83% for Sn and 23.68% for Ba, respectively. The finer adsorbent with large surface area was more effective. Similar results were obtained for PW samples from the other fields. Sequential mixture of the bio-adsorbents selected proved valuable in the treatment of contaminants in PW from Niger Delta oil fields.

Treatment of produced water from Niger Delta oil fields using simultaneous mixture of local materials

Produced water (PW) from petroleum reservoirs often contains heavy metals and other contaminants that are harmful to the environment. Most of the commonly used treatment techniques have been reported to be ineffective in reducing some of the contaminants’ concentrations to recommended disposal levels. This study evaluated the effectiveness of four selected bio-adsorbents combined for treating PW from Niger Delta oil fields. In this study, orange peels (I), banana peels (II), sponge gourd (Luffa cylindrica) (III) and palm kernel fibers (IV) were washed with distilled water, sun-dried (24 h) and dried in the oven at 105 ± 5 °C (3 h, I and II), 150 °C (30 min, III) and 80 °C (3 h, IV). They were ground into powder, sieved (150 μ, Group A) and (300 μ, Group B), washed with 0.4 mol/L HNO3, filtered and rinsed with distilled water. Samples of PW were obtained from fields R, X, and Y in the Niger Delta and analysed for heavy metals using an atomic absorption spectrophotometer (AAS). Samples were treated in adsorption column over 6 h using the adsorbents simultaneously. Treated samples were analysed with AAS and characterised. Adsorption of heavy metals were assessed using Langmuir and Freundlich models. Data were analysed using regression and other statistical methods. For the 150 μ size of sample R, the percentage reductions for the metal concentrations (Pb, Ni, Cd, Cu, Fe, Mg, Cr, Zn, Mn, Ca, Ar, B, Sn and Ba) were found to be 100%, 52.7%, 100%, 100%, 85.87%, 19.48%, 100%, 92.8%, 17.74%, 98.86%, 22.32%, 29.56%, 78.06% and 44.74%, respectively, while the reduction in 300 μ size were 1.52%, 97.2%, 71.4%, 17.1%, 43.8%, 45.6%, 7.04%, 89.6%, 35.4%, 99.6%, 0.0001%, 1.19%, 14.19% and 0.002%, respectively. The finer adsorbents were more effective. Similar results were obtained for PW samples from the other fields. Produced water from Niger Delta oil fields was effectively treated of contaminants using four selected bio-adsorbents mixed simultaneously.

Economic Analysis of Low Salinity Polymer Flooding Potential in the Niger Delta Oil Fields

With the current growing demand for oil, oil price and the concerns about future oil supplies increases the pressure in securing oil resources. Enhanced oil recovery processes are applied to recover oil not produced by natural and secondary energy drive of the reservoir. In this study, Simulation has been carried out on a hypothetical model using (ECLIPSE 100) as the simulator. Three cases natural depletion, waterflooding, and injection of low saline polymer were considered.5-spot pattern of four vertical producers wells and one vertical injector well was used as a hypothetical well model. Economics analysis were carried out in this three scenario to determine their net present value, profit per dollar invested, payout and Discounted flow-rate of return. The results shows that low salinity polymer flooding has the highest recovery of 62% and profit with NPV @ 10 ($412.9MM), payout 0.9 years, profit per dollar invested $25.9 and dcf-ror 82%. However, waterflooding gave recovery of 42%. NPV @10 ($ 317.3MM), payout 1.2 years, profit per dollar invested $20.8, dcf-ror 78%. Natural depletion gave recovery of 16.5 %, profit with NPV @10 (230.0MM), payout 1.0 years, profit per dollar invested $9.3, dcf-ror 78%. Decision rule was applied using NPV, DCF-ROR, NCR and payout which states that project with higher NPV, DCF-ROR, NCR and less Payout are more economically viable. The result of the three cases considered shows that low salinity polymer injection is more profitable followed by waterflooding and natural depletion.

Optimizing Production in Brown Fields Using Re-Entry Horizontal Wells

Reviewing of some Niger Delta oil field reservoirs indicate that most of them are brown fields, thereby vulnerable to challenges such as; coning due to reduced size of the oil column, low oil production and lack of access to the residual oil trapped between existing wells of the brown field. Due to coning occurrences in the Niger-Delta brown oil field, most wells have been shut-in and a lot of recompletions are being made in order to combat this problem. To proffer solutions to these technical challenges of these brown oil fields, this study seeks to review the potentials of re-entry horizontal well technology and its viable application to optimizing oil production from brown oil field. Re-entry horizontal well Technology involves a method of converting an existing vertical well into an horizontal well to save cost as oppose to drilling a fresh horizontal well from the surface. The object of the re-entry well is to reduced cost, especially in areas where drilling costs are very high. The re-entry horizontal in this research was represented by a virtual horizontal well to study the potentials of producing brown fields. The simulation paradigm studied was Black oil with light oil type variation of 32 O API. This article is therefore aimed at suggesting the conversion of existing vertical wells in the Niger-Delta into re-entry horizontal wells as a measure to optimize oil productionof these brown oil fields.

INVESTIGATING ELECTRICAL RESPONSE TO WATER SATURATION OF AGBADA SANDSTONE IN AN X-FIELD NIGER DELTA, NIGERIA

In an attempt to characterize a reservoir in a field, importance is given to living models as it serves critical function in estimating if the reservoir under study is economically viable. Having a good knowledge of electrical response to reservoir rocks is important in characterizing and modeling the behavior of fluids at the subsurface. In this study, core plugs extracted from core barrels in a Niger Delta oil field were analyzed in the laboratory in order to determine the electrical properties of the samples and their relationship with each other and formation fluid. This was achieved by using a brine of a known concentration for simulation of core plugs. Results obtained show that for the unconsolidated sandstone, Formation resistivity factor increases with an increase in confining pressure. This characteristic depends on the porosity of the Formation and type of fluid present. Resistivity values in a reservoir will increase with an increase in capillary pressure and decrease with water saturation. The decrease in cementation exponent increases the rate of permeability in reservoir sand. However, resistivity values decrease with clay presence in reservoir sand.Keywords: Core plug, reservoir, resistivity, water saturation DOI 10.35180/gse-2019-0015

Distribution of methylhopanes in some Niger Delta oils

A suite of oil samples from Niger Delta oil fields were examined for compositional distribution of methylhopane. The samples were obtained from wellhead of oil wells and stored in sample bottles. The oil samples were fractionated and the saturate fraction was subjected to gas chromatography/mass spectrometry (GC–MS) analysis. The methylhopanes in the oils were identified, their abundance delineated, and are of potential use for oil characterization. The mass chromatograms of m/z 205 were extracted and the peaks identified using GC–MS library, literature, and mass spectra form the library. 2α–Methylhopanes and 3β–methylhopanes were identified in Nigerian Niger Delta oils. North Sea and Venezuelan Boscan oil were also examined. Generally, the Nigerian oils showed higher abundance of 2α–methylhopanes and lower abundance 3β–methylhopanes compared to the Boscan and North Sea oils. The plot of C30 hopane/C30 2α–methylhopane and C30 hopane/C30 3β–methylhopane for all the oils showed the discrimination of the oils into Niger Delta, North Sea, and Venezuelan Boscan oil. The ratio of C30 hopanes/methylhopanes can be applied as a correlation tool.

Producibility Scenario of Unidentified Productive Zone

Reservoir studies of naturally repressured reservoirs are highly problematic. Thus, their reserve estimation is notoriously in error. This is aggravated by the presence of communicating areas. The repressurization is due to the enhancement of the reservoir energy sourced by additional undeveloped productive zone(s). The aim of this study was to determine the source of constant recharging (repressurization) of a reservoir in the Niger Delta Oil Field. Several techniques were adopted to investigate the source of repressurization of the reservoir. An unknown productive zone was identified to be communicating with the reservoir which increased the STOIIP by over 100%.