bluuebunny/crossref_metadata_2025 huggingface dataset:
Formation Evaluation of Magnetic Resonance Logging-While-Drilling Data Recorded at a High Rate of Penetration
Authors: Oifoghe Stanley , Thern Holger , Coman Radu , Okowi Victor , Sy Rex
Published: October 2018

Magnetic resonance (MR) logging-while-drilling (LWD) data have numerous petrophysical applications for reservoir characterization. Under certain conditions, a high rate of penetration (ROP) can affect the data quality of MR LWD T2 distributions, compromising some of the estimated petrophysical properties. Logging MR data at a low ROP was so far the recommended approach to ensure high MR data quality. Moreover, when high ROP could not be avoided, ROP effects were a reason to consider the MR data to be of very limited or no value.

Recently, an ROP correction for MR logging data was introduced. The correction on porosity is particularly significant for large volumes of light hydrocarbon (HC) with a large T1 value. For best results, the MR logging data should comprise an extended data set, e.g., including echo trains with full and partial polarization of the light HC that enables the calculation of an in-situ T1 of the light HC. Extended data are, however, often not available in older data sets—a condition not discussed in detail before.

This paper presents a case study based on MR data recorded offshore Nigeria many years ago. The well was drilled with an ROP exceeding 40 m/h, which was twice as fast as the typically recommended maximum ROP at the time. The logged reservoir has a porosity of 30 to 35 p.u., and it contains light oil and has a high oil saturation. The ROP polarization effect caused a severe porosity overestimation. At that time, no ROP correction was available, and the MR data were considered not suitable for petrophysical interpretation because of the porosity overestimation.

The recently introduced ROP correction was successfully applied to the log data using a constant T1/T2 ratio value for estimating T1 of the light HC from the acquired T2 distribution. The correction results show that the MR total porosity was severely overestimated without correction. However, the porosity overestimation was only related to an increase of the light oil porosity. The volumetrics and the T2 distribution of the irreducible fluid fraction remain unaltered by the correction.

Consequently, valuable information can still be extracted from the uncorrected T2 distribution. First, the uncorrected MR data enables a simple computation of saturation, which is in good agreement with the resistivity-based saturation. Second, the amount and position of the bound-water peak correlates to variations in rock type and quality. Third, the position of the light-oil T2 peak indicates variations in mineralogy, because it correlates well with variations in the gamma ray (GR) log curve.
Impetus and Impediments in the Nigerian Content Law: A Sabbatical Review
Authors: Olatoye Deji
Published: October 2018

The theoretical bases for the body of policies for the development and utilisation of local capacities in general or in specific industries – now generally referred to as ‘local content’ policies – are of long standing. Evidence of their existence has long been scattered in white papers and the statute books of developing countries. From international trade perspective, it partakes of the protectionism-competitiveness debate regarding the mediation of imported capital vis-a-vis domestic capital formation. That debate itself, however, begs the question as it presupposes the existence of a fairly formed local industry worth protecting. From the standpoint of the global value chain, a local content policy aims to help countries that traditionally occupy the head-end of inbound logistics in global industries gain on a longer stretch of the chain. Furthermore, from the perspective of industrial policy, it provides an option by which developing countries grow local participation in strategic industries – this time, through the empowerment of local enterprises rather than the agency of state holdings as in traditional in industrial policies. Prior to 2010, legislations in Nigeria are strewn with provisions that promote the systematic acquisition of technological and management skills, regulate the utilisation of expatriate workforce as well as prefer if not entirely preserve local participation in certain categories of businesses and professions. In recognition of the central role of oil and gas in the Nigerian economy, Nigerian Oil and Gas Industry Content Development Act (‘Nigerian Content Act’) was passed in 2010. Seven years after that landmark event, this paper reviews the virtual framework created by the pre-existing laws and highlight the novelty of the Nigerian Content Act and its proposed amendment. It concludes that, whilst many of the provisions of the Nigerian Content Act brought about a number of improvements to the subject matter, some others have potentials to tame the effectiveness of pre-existing laws. Since some of the confusions introduced by the latter category of provisions are largely due to poor draftsmanship, the paper also identifies some key provisions that could benefit from a second take by the draftsman.
Meta-Modeling Evaluation of the 2017 Petroleum Industry Fiscal Reform Terms on Deep Offshore Assets in Nigeria
Authors: Ojaraida Lolo , Iledare Omowumi , Akinlawon Adeyemi
Published: October 2018

Deep offshore hydrocarbon resource development in Nigeria is of great economic interest due to security challenges limiting direct investment flow to onshore petroleum assets. However, Petroleum fiscal systems, which basically describe the relationship between host government and International oil companies (IOCs), are paramount in the deep offshore investment decision process. This paper focuses on assessing the implications on deep offshore asset development economics under the 1993 Production Sharing Contract (PSC) terms in comparison to the fiscal terms in the 2017 petroleum industry fiscal policy reform report.

A metamodeling framework is proposed and applied in this paper. The framework adopted involves the development of deterministic cash flow models for both the 1993 PSC and the 2017 proposed fiscal terms. A range of profitability indicators for economic evaluation is generated and Monte Carlo simulation using @Risk software is applied to account for risks and uncertainties.

The results reveal that the 2017 fiscal terms appear to be favorable to the contractor based on selected profitability indicators. In addition, there is strong evidence to suggest that the dual tax system proposed in the 2017 fiscal policy is economically attractive to the contractor when compared to the single tax system in the 1993 PSC. Hence, deep offshore E&P development is expected to be more rewarding to contractor under the 2017 draft fiscal policy terms than the 1993 PSC terms, ceteris paribus.
Prototyping, Analysis of the Performance of a Beta Type Stirling Engine for Power Generation
Authors: Ajisafe Oluwagbenga
Published: October 2018

A stirling engine is prototyped after subjecting to computational analysis using Computer Aided Design and Development processes. The design objective includes; 37% efficiency and a power output of 1.5KW. The analytical processes utilizes Beale/West, Schmidt, Ideal, Adiabatic method as well as Simple Analysis for proper estimation of the engine's performances. The critical factors during the preliminary design process include; heat loss, dead volumes and pressure drops. Gaps between the regenerator and the seating, as well as high performance ceramic seals are introduced to reduce heat loss by conduction. Careful analytical processes and design were carried out to ensure a compromise that reduces pressure drops and dead volumes while reducing heat losses. The prototype was fabricated locally, and it demonstrated a wonderful design process.
Assessing the Effectiveness of Ergonomics Practices in Selected Workplaces in Port Harcourt, Nigeria
Authors: Okoye Esther Amaka , Ugbebor John , Adaramola Samson
Published: October 2018

The study was carried out to determine the level of ergonomics awareness and the level of implementation/practice of ergonomics is selected workplaces in Port Harcourt. Ergonomics should be major emphasis at the workplace in designing of task to fit to the workers capabilities. Problems associated with major activities include extreme temperatures, noise, slippery surfaces, manual handling, exposures of carrying, lifting, lowering, forceful pushing and heavy pulling of tasks leading to occupational diseases. Collections of primary data were by means of questionnaires administration to 150 persons, amongst the number distributed 120 questionnaires were retrieved. 42 from Exploration and Production, 38 from Oil and Gas Servicing, and 40 from manufacturing industry representing a response rate of 80%. 20 questions were designed as questionnaire parameters; the first 10 are to assess the level of ergonomics awareness amongst workers in 3 selected workplaces in Port Harcourt, while the second 10 are to evaluate the ergonomics implementation/practice in three selected workplaces in Port Harcourt. The responses are rated strongly agree (4), agree (3), disagree (2) and strongly disagree (1). The approach was necessary to facilitate the evaluation of Kendall's coefficient of concordance (W), that is, the degree of agreement amongst the respondents. The results revealed on the average, an appreciable level (75%) of awareness and (53%) level of ergonomics implementation/practice amongst the respondents, respectively. Lack of awareness on static loading as a risk factor in ergonomics, non-availability of good fitting thermal gloves to help with cold conditions, noisy machines not being isolated, non-availability of lumbar support chairs (adjustable task chairs), and finally, not conducting health examination surveillance on workers periodically are the gaps identified. Kendall's analysis revealed a high degree of agreement amongst the respondents on both ergonomics awareness (0.74) and ergonomics implementation/practice (0.99), respectively. Thus, the study recommends more ergonomics trainings on workers, provision of lumbar cushions, isolation of noisy machines, provision of good fitting thermal gloves and periodic health examinations on workers.
Optimum Well Type for Oil Rim Reservoirs with Large Gas-Cap and Strong Aquifer
Authors: Ogiriki Shadrach O. , Imonike George O. , Ogolo Naomi O. , Onyekonwu Mike O.
Published: October 2018

Oil rim reservoirs are often troublesome to produce commercially as a result of the adverse effect of coning and cusping/cresting. In this study, deviated and horizontal wells were employed to determine the optimal well type to be drilled in the "GISO" oil rim reservoir in order to attain optimum oil recovery while reducing uneccessary cost. The GISO oil rim reservoir considered in this study had a thickness of 8ft with grid dimensions of 91×74×20 in the i, j, and k coordinates respectively, and contained a dynamic reservoir oil volume of 9.37MMSTB. Results obtained from simulation revealed that there was not enough oil recovered from the subject oil rim reservoir, owing to the fact that that the reservoir had a very small oil column thickness and this led to the early encroachment of water into the oil column. Three horizontal wells and one deviated well were simulated in the oil rim in order to determine the preferred well type for optimum hydrocarbon recovery for a period of 20 years. The four cases were simulated with a constant production rate of 2000STB/D. Well H1, a horizontal well with lateral length of 272ft recovered 840MSTB, while well H4, a deviated well with a deviated well case with an inclination angle of 84.20° from the GOC and lateral length of 242ft recovered 830MSTB.
Results-Oriented Land Asset Management Using Numerical Model
Authors: Okpo Ekpenyong E. , Onyekonwu Mike
Published: October 2018

The Oil and Gas industry is a melting pot for assets and technology and thus requires an ingenious management of the duo to achieve sustained goal of reduced operational cost and maximized profits. Incidents on typical land assets like pipeline located on acquired or leased areas have been known to cause companies a lot, including huge litigation payments, downtime, damaged public image and even threat of business closure. Studies indicate that various tools are currently being used to manage land assets, including third party solutions, spreadsheets, homegrown software solutions and database software. A comparative study was carried out using the Crystal Ball and OptQuest excel add in to determine an effective solution that will maximize Total Economic Value Added (EVA).

The result shows that the choice made is a one-time decision; each solution will either be successful or not. If a project is not successful, the company runs the risk of incurring the loss of the initial investment and maybe even its faith in that project. Thus, the goal is to incorporate risk analysis within the context of the project selection, and to select the best projects that satisfy input constraints while optimizing the EVA
Benchmarking and Prediction of Ultimate Recovery Based on Performance Data of a Mature Brown Field: A Case Study From Deepwater Nigeria SPE- Paper Id 130
Authors: Oshomah Hakeem , Ghosh Ankush , Awasthi Amit , Njoku Chukwueke , Olatunji Idris , Hafiz-Ringim Mohammed
Published: October 2018

Eko is a prolific Deepwater brown field on production for 10+ years and cumulatively produced ~750MMSTB from 30+ producers and 25+ injectors (average cumulative production 25MMSTB/well). However, the actual ultimate recovery developed by producers vary from <10MMSTB to >90MMSTB which can be attributed to STOIIP distribution, reservoir complexity & development strategy. As the field has matured to production plateau and with sufficient static & dynamic data now available, a Deepwater Analogue study was kicked off to develop an Ultimate Recovery(UR) predictive model to benchmark the robustness of the simulation predictions for the next phase of in-fill development wells. This database will also support the quick evaluation of other Deepwater fields which are in advance stages of hydrocarbon maturation funnel. An integrated study was carried out to collate all static/dynamic data in each reservoir/well. Drainage area for each producer(s)-injector(s) well pair was defined (Figure 1) and associated average reservoir properties were estimated from latest history matched models. Several combinations of parameters were cross-plotted against the objective function (UR/Well) and a proxy function was established to predict UR for future wells. An error analysis was carried out on the reference case function to establish prediction uncertainty ranges. The simulation based P90/P50/P10 UR ranges for the future in-fill development wells were compared with this analogue database and where the forecasts from models were not in sync with actual observations in Eko field, modeling assumptions were revisited. As way forward, this analogue database will be updated with new well information, static re-modeling and/or history matching exercise. Also, the in-fill well results will be used as litmus test for the robustness of the analogue model.

Figure-1 Amplitude Map Showing Definition of Drainage Areas for Major Reservoir (Red wells = Oil Producers, Blue wells =Water Injectors)
Effect of Pipe Inclination on the Hydrodynamics of Slug Flow
Authors: Dafyak Longtong , Appah Dulu , Onuoha Sean , Mukhtar Abdulkadir
Published: October 2018

There is a general lack of studies addressing the optimization of hydrocarbon flow conditions in pipes passing through hilly terrains. Most of the studies carried out on two-phase flow are for fluids flowing through vertical and horizontal pipes. For studies carried out on inclined pipes, a large proportion are on air-water mixtures. To address the aforementioned challenge, there is a need to study the hydrodynamics of slug flow in various pipe inclinations with a focus on fluids with properties that replicate the behavior of effluents seen during crude oil production.

This study provides a foundational perspective into the physical phenomenon that governs the behaviour of slug flow and the variation of slug flow parameters as the pipe deviated from horizontal to vertical. To clarify the effect of pipe inclination on the hydrodynamics of slug flow, the characteristics of fully developed multiphase air-silicone oil mixture flowing in a 67 mm diameter pipe and inclined at 0, 30, 45 and 90 to the horizontal was investigated. Fluid flow properties over the range of superficial gas and liquid velocity were measured using Electrical Capacitance Tomography (ECT) and analyzed using Probability Density Function (PDF) and Power Spectral Density (PSD) plots to determine; mean void fraction, void fraction in the liquid slug and Taylor bubble, structure velocity, slug frequency and slug unit.

The mean void fraction decreased as the pipe inclination advanced from 0° to ~45°, it then increased between ~45° and 90° to the horizontal; the angle at which it begins to increase seems to be around 45°. The void fraction in the liquid slug increases as pipe inclination tends towards the vertical from the horizontal axis. In the case of the void fraction of the Taylor bubble, no unique trend was observed as the pipe inclination changed. The slug frequency increased with pipe inclination and liquid superficial velocity at a constant gas superficial velocity. In addition, the structure velocity increased as the pipe inclination advanced from 0° to 45°, it slightly decreased again between 45 and 90 to the horizontal. The slug unit in horizontal pipes is far greater than that obtainable in pipes inclined between 30° and 90°, at superficial velocities of 0.05 m/s and 0.157 m/s. However, at higher superficial velocities between 0.262 m/s and 0.514 m/s, the slug unit ranges from 0.6 to 1.8 m for all pipe inclinations. It was also confirmed that for upward inclined flow, the dominant flow pattern is intermittent flow.
Type-Curve Analysis Using Homotopy Analytical Technique for Evaluation of Reservoir Rock Properties
Authors: Ayuba Ibrahim , Adamu M. B. , Salahudeen Ibrahim , Faruk A. U. , Ismail H.
Published: October 2018

Homotopy analytical method (HAM) is a computational method that provides solution to highly non-linear partial differential equations (PDE's) in much similar way as other perturbation and asymptotic techniques. This research work illustrates the benefit of using (HAM) to obtain a type curve over conventional log approximation of dimensionless variables. From such type curves, average reservoir properties, porosity and permeability were obtained from dimensionless equations. This type curve was obtained by matching plots from HAM solution and well test data. The HAM is independent of small/large parameter and can be used to obtain analytical solutions to highly nonlinear partial differential equations unlike other analytical and asymptotic techniques applies to weakly nonlinear problems. The HAM solution gives values of reservoir pressure distribution as a continuous function of time and converges easily for large reservoirs (rD =380) typically. One advantage of HAM is that it provides a means to ensure convergence of series solution by introduction of convergent control parameter. Plots of reservoir pressure distribution as a function of time curves were also obtained and extrapolated for easy matching and were matched with the type curve. Dimensionless pressure and time were used to compute average porosity and permeability which were found to be 1.51md permeability and 1.81% porosity. Computer program was developed for computations using MATLAB and further analysis of data using EXCEL. From the match points obtained, reservoir properties were estimated.
Completing the Value Chain for Plastic Recyclers in Nigeria: An Integration of Renewable Solar and Conventional Gas Energy Sources for Fuel Production
Authors: Stephen Okocha , Okonkwo Ebenezer , Ogbonna Joel
Published: October 2018

It is of no new update that plastic recycling has taken another dimension in advanced countries all around the world. This is owing to the enormous plastic wastes being produced amounting to about 9 billion tonnes since the first production and the immerse technological advancements which can be seen in pelletizing plants, pyrolysis plants and 3D printers of today. However, here in Nigeria, the case of large plastic waste generation cannot be over emphasized, as efforts in recycling has being hampered consequently from low power generation of the National grid, high energy cost (fuel and electricity), polymer waste selectivity and even low capital resource from most parts of the country. Hence, this paper looks at the development of a solar-vacuumed actuated pyrolysis plant integrated with gas combustion energy supply which will employ the use of concentrated solar energy as the primary energy source for pyrolysis reaction for fuel production and use the flee gas from the reaction as an alternative energy source. A process flow configuration (PFD) involving the reactor, solar lenses, vacuum pump, solar panel, inline components and the condenser is set up to perform the thermal gasification and condensation of waste plastics in the reactor. Computationally, the finite element analysis (FEA) was done to see the thermodynamic effects inside and outside the reactor for effective fuel production. The idea is to ascertain that the inside temperature of the reactor which was initiated by solar thermal energy is enough to attain the boiling point of about 400°C of most plastic polymers but in vaccum conditions. When accomplished, this will complete the value chain of plastic recycling, eliminate plastic waste selectivity in terms of colour and type, sanitize the environment and create jobs for future entrepreneurs in Nigeria.
Alerting Excessive Choke Increase Impact on Water and or Gas Production Responses Vs. Oil Cumulative- PredOPT
Authors: Morais E. I. , Fernandes G. C. , Chitangueleca B. , Ibelegbu C. C.
Published: October 2018

Angola's O&G business environment has shifted from Exploration to Production, and from Drilling to Well Intervention for obvious reasons of current and projected state of the E&P industry where operations are squeezed by volatile oil prices and higher operating costs. Operators in quest to maintain production plateau resolve in excessive choke increase. Therefore, a focus on predicting resulting HWcut and or HGor over time becomes significant as 75% of fields are under fluid injection for a balance voidage replacement.

This study uses fields in Angola for conventional diagnostics decline curve analysis. Using plots of cumulative oil vs GOR, Pressure, Water cut and choke, to analyses the water and or gas production responses vs. oil cumulative to the excessive choke change. To have a complete sense of the impact, PI is included to consider oil production with respect to pressure drawdown. This study where mainly focused in clastic deposits.

This approach may help anticipate the production of water due to excessive increase in choke sizes. It is expected that depending on the provenance of the water, it is concluded that excessive choke variation can be problematic in the future. A possible warning or alert is generated for any future choke change and hence oil production is optimized. An excel macro coding- PredOPT (Prediction and Optimization) is developed for the analysis and plugged-in to commercial software for the ease of applicability.
A Look at History-Match Non-Uniqueness Through the Lens of Model Simplifications - Delta Reservoir Case Study
Authors: Jaja Adagogo J. , Ambastha Anil , Aina Soji , Eme Vincent , Bere Barienea
Published: October 2018

Reservoir simulation is one subject with different "schools of thought" for its ability to predict the future performance of a reservoir. An important topic in reservoir simulation workflow is the parameters used to achieve history-match. The non-uniqueness of history-match parameters creates an opportunity for reservoir simulation engineers and geologists to engage in collaborations that ensure geological and engineering interpretations are incorporated in history-match parameters.

Simple history-match parameters are often times preferred by practitioners to complex history-match parameters. This paper will discuss Delta reservoir history-match parameters used in a 2014 reservoir simulation study which was later updated in 2016 with simplified history-match parameters. The parameters that were simplified are permeability multipliers, oil/water relative permeability and the use of Land's constant. Also, vertical grid refinement was implemented to reduce it from 8ft to 2ft to enable the simulation model reproduce the reservoir fluid distributions in the two lobes of the reservoir. With all these modifications, there were no significant differences with the wells’ static reservoir pressure and fluid saturation matches between the 2014 simulation study and the 2016 simulation update. This paper demonstrates the non-uniqueness of reservoir simulation history match parameters and the value to consider simple grid and fluid parameters’ modification before considering complex approach.

With the simplified history-match parameters, the Asset Team had more confidence in the simulation result. The updated Delta reservoir simulation model was used to assess future development opportunities and identified two oil-well producers and one water injector well with EUR of 13.3 MMSTBO.
Development Strategies for Oil Reservoirs with Coning Problems: A Simulation Case Study
Authors: Stanley Okafor Ikechukwu , Ebenezer Ubani Chikwendu , Anyanwu Nnaemeka
Published: October 2018

Water coning in oil reservoirs is a complex phenomenon which poses a problem in the petroleum industry today. The upward movement of water into the production interval has an adverse effect on the production facilities and the total oil recovery of a particular field. In this paper, different strategies for analyzing and developing reservoirs with coning problems were developed and different implementation steps were suggested to properly optimize the recovery of these reservoirs. Our case study is an oil reservoir in the Niger delta region with strong aquifer drive. A numerical reservoir simulation study was carried out based on the structural top and base maps generated using 3-D seismic estimated reservoir rock and fluid properties, using actual reservoir/well data. Also, production performance analysis were carried out to ascertain the causes of non-conformance issues like high BSW, decline in production and reservoir pressure. Perforation panel plots were constructed for the Levels with respect to the initial fluid contacts to diagnose for high water cut, to investigate their impact on future performance scenarios and productivity of the currently producing wells. The recommended development scenarios were also compared with the nature and structure of the reservoirs (high dip and low dip) to show the best well patterns/placements that will improve recovery.
Profitability of Marginal Oilfields in a Low Oil Price Regime: A Stochastic Modelling Analysis
Authors: Adeogun Oyebimpe , Iledare Omowumi , Idowu Adekunle J.
Published: October 2018

Marginal fields are typically characterized by low reserves, high sensitivity to oil price, high subsurface uncertainties, and significant economic and technological constraints. Despite these challenges, they remain a viable tool for local content and sustainable economic growth. Recent reports showed that they accounted for about 10% of total crude oil production in Nigeria. This contribution is quite low but more might be expected in the coming years. The interplay of cost, oil price and fiscal regime has significant impact on the profitability of marginal field assets because of the small reserves size. With persistence low global oil price regime, it has become imperative to critically analyze the economics of marginal oil fields in Nigeria. It is usual for government to design stable and flexible fiscal regimes for marginal field operators in order to capture unforeseen uncertainties peculiar to the oil and gas industry. This paper seeks to examine the profitability of marginal field operators under the prevailing fiscal regime. In addition the paper intends to recommend measures that can be taken to ensure profitability of marginal field despite declining oil prices. An economic model and stochastic simulation using prevailing fiscal regime showed that marginal field operations will be profitable if and only if reserves were at least 10 MM bbl. However, for smaller field size than 10 MMbbl, marginal field development may only add value with economic and policy incentives and cost minimization strategies. Thus, it is recommended that tax holiday should be given when oil price drops below $35/bbl. in order for marginal field development to add value.
Analysis of Government and Contractor Take Statistics in the Proposed Petroleum Industry Fiscal Bill
Authors: Nwosi-Anele Adaobi Stephenie , Adeogun Oyebimpe , Iledare Omowunmi
Published: October 2018

Fiscal system is the basis for the estimation of take statistics ratio between Government and Contractor. This has been the case for the different versions of Nigeria's Royalty and Tax system and Production Sharing Contracts. Modifications in the currently proposed petroleum industry fiscal bill promise to ensure oil and gas availability, accessibility and affordability. Favorable upstream petroleum operations underlie the development and expansion of the midstream and downstream sectors. Fiscal incentives available to contractors make investment a worthwhile venture for both the government and contractor. The recently proposed petroleum industry fiscal bill (PIFB) 2017 is a favorable development because it is anticipated to reduce tax burden on investors, increase government take from royalty schemes and a dual tax system imposed on oil and gas projects. This paper applies a deterministic and stochastic cash flow model, analyzes the fiscal provisions of the existing royalty and tax system, production sharing contract and the proposed petroleum industry fiscal bill, 2017. Results from the model present a friendly royalty and tax deduction strategy in the proposed bill, which provides an incentive for investors to re-invest in the midstream and downstream sectors. However, the provision in the petroleum industry fiscal bill (PIFB) 2017 for royalty deduction during windfall is rather too fair at $50/bbl, considering a benchmark profitable oil price of $35/bbl during windfall. This paper suggests $35/bbl price for windfall threshold price for the additional $0.2 per dollar increase in oil price for royalty by value determination.
Silica Based Surfactants for Enhanced Oil Recovery
Authors: Adeniyi Adekunle Tirimisiyu , Olafuyi Olalekan A.
Published: October 2018

A new silicate based surfactant, comparatively proven to be cheap and efficient, for enhanced oil recovery is developed. The silica based surfactant was prepared from silicate with highest percentage of silica and evaluated for reduced interfacial tension, and core flooding experiments simultaneously with sampled commercial surfactants, for its potency to aid oil flow. The feedstock, for silica based surfactants, composed massively abundant eartly silicate, rich in silicon. The silica is hydrolyzed at elevated temperature and continously heated up to form oxides of silica. The performance of the silica based surfactants was studied for its oil recovery efficiency with a commercial surfactants as a guide. The results showed that silica based surfactants dissolves in produced water, an adjusted interfacial tension value of 0.101dyne/cm was obtained. An improvement of additional 10% of oil initially in place was produced ahead of a branded commercial surfactants, from a set up that has undergone excessive water flood. The results obtained, confirmed that there is a possibility of developing new surfactants from sustainable abundance of earthly silicate.
Managing Shallow Casing Leaks in Well Completions; Case Study of a Single Zonal Well in Niger Delta
Authors: Oghale Longfellow , Noruwa Osahon , Osadebea John , Jordan Fisayo , Simon Osa , Emmanuel Ejimofor
Published: October 2018

Re-entering old and mature wells is necessary to chase initially classified marginal hydrocarbon volumes. Many wells drilled in the 60s and 70s but suspended have become attractive to small players with relatively low overheads and tax regime. As a marginal field operator, such opportunities are classified as short term development opportunities establishing quick cash flow to further field development.

Casing failure in an old well drilled through shallow faults can pose serious challenges to re-entry and workover operations. This paper presents the solution to a challenging casing leak interval across a shallow fault zone which could not be squeezed off with conventional cement squeeze technique.

The failure of routine casing test prior to drill stem test during a re-entering and completion of a well drilled and suspended for 36 years necessitated the consideration of several isolation methods. Attempts made to squeeze off the leak interval across the fault zone using cement proved abortive due to the size and nature of the fault. Casing patch was considered but not available in-country as at the time of the operation. This led to a novel approach of isolating the leak interval with the completion packers and subsequently perforating the well through-tubing. The leak was successfully isolated and the well completed. The well has produced over 0.5 million barrels of oil and 4.5 billion standard cubic feet of gas and still contributing over 10% of daily field production. This method was also used in a dual completion in Niger Delta to manage two different pressure gradients.
Multi-Rate Testing via Gas Plant with Clamp-On meters: A Niger Delta Case Study
Authors: Mogbolu Emmanuel , Udobata Uchenna , Amaefuna Magnus , Okereke Onyedikachi , Oghene Nkonyeasua
Published: October 2018

The primary focus of a Well, Reservoir and Facility Management (WRFM) team is to guarantee shareholders’ return on investment by improving production and optimizing recovery. Several best practices abound in the industry to achieve this goal. Multi Rate Testing (MRT) is a statutory requirement on gas wells; one of the most important functions of MRT is to obtain the wells’ deliverability for optimal reservoir management. Obeahon et al (2015) had presented an alternative approach to Multi-Rate Testing using existing gas central processing facility. This approach is applicable provided all the metering equipment are installed. This paper presents an alternative MRT approach for gas plants which do not have all the metering equipment installed. This was applied in the OMAUO Field and can be applied on other fields with similar situation. OMAUO NAG (ONAG) operations had been plagued with the following problems: the absence of wet gas meters to measure the well potentials, uncertainty with CGR/WGR of the wells for model calibration/ well's optimization, challenge of conducting conventional MRT via third party due to cumbersome logistics/cost (ca. US$ 2 mln/well) and no test facility. Thus, potentials and deliverability can only be assessed via third party MRT operations and absence of wet gas meters had limited the ability to use the Gas Plant to carry out MRT. The proposed approach was executed by utilizing clamp-on meters (to measure wet gas) at the manifold and the Gas Plant as a giant test separator for the individual well testing. Pilot tests were successfully carried out on three wells that were tested individually (OMAU015T, 016T and 017T). The technical integrity of the acquired data was in line with that obtained from MRT via a test separator and the results of the analyzed data were found to be representative. The low CGR and WGR values obtained from the analysis also aligned with that obtained from the previous MRT (via third party mobile test separator). The pilot tests saved US$8mln for four wells tested with minimal HSSE exposure, gained additional volumes of gas (ca. 50 MMscf/d) due to the optimization exercise, reduced deferment by reducing execution time and aligns with the competitive drive within the oil and gas industry. The outcome of carrying out this pilot test via the use of clamp-on meters can be leveraged upon by other gas plants without requisite meters and test facilities.
Improved Water Soluble Polymers for Chemical Flooding
Authors: Eiroboyi I. , Ikiensikimama S. S
Published: October 2018

Nanotechnology has shown enormous progress in the petroleum industry especially in the area of Enhanced Oil Recovery. However, field experience has shown that the major challenge facing polymer flooding is polymer degradation under reservoir conditions such as high temperature and high salinity. Though Partially hydrolysed polyacrylamide (HPAM) is the current widely used polymer, it is also very sensitive to salinity, shear, thermal degradation due hydrolysis of polyacrylamide introduced as a result of negative charges on the backbones of polymer chains which in turn causes an alteration on the rheological properties of the polymer solution.

The rheological behaviour for different solutions of Guar gum and Gum Arabic containing different salt was evaluated to study the effect of nanoclay and other additives on the stability of these biopolymers. The viscosity of these polymer solutions was measured using a rheometer and in each measurement, the shear rate was changed, and the effect of this change on the viscosity was measured. Results showed improved stability at different range of salinity and level of concentration of the polymers.
Reducing TVD Uncertainties Using Dual Inclination and SAG Model
Authors: Ulaeto Ubong , Nwobi Zimuzo , Ibrahim Hamza , Ubadigha Emmanuel , Asiodu Ndidi
Published: October 2018

Uncertainties in True Vertical Depth (TVD), over the years in the practice of drilling, have been a concern for precise wellbore position and collision avoidance. Accurate well placement in thin oil bearing zones have necessitated service companies to design Bottom Hole Assemblies (BHA) capable of providing actual hole inclination with high precision.

TVD accuracy is normally a function of Measured Depth error and Inclination error. These errors could arise from sensor calibration, misalignment error and BHA Sag. In highly deviated wells, inclination is the dominant contributor to TVD uncertainty. Reduced inclination uncertainty therefore results in reduced TVD uncertainty. By measuring the inclination of the well at same depth with different sensors positioned in different locations in the BHA in rotary or non-rotary mode, the improved accuracy in TVD is achievable. This technique, also known as Dual Inclination, is a survey method used to increase inclination accuracy, and thereby reduce TVD uncertainty.

This paper discusses practical field cases for two long tangent and horizontal wells drilled at different locations of West Africa where Sag corrections and dual inclination were utilized to reduce the error in TVD prediction. The technique was adopted to avoid collision with existing and future wells and produce the oil rim in the zone of interest. Final results showed difference of 2ft and 3ft in TVD for both wells with 6ft and 4ft difference in vertical uncertainties respectively. The data utilized for this study were obtained from the well survey from the two sensors within the BHA. Also discussed are the Quality Control criteria to be met for right application of this technique. Recommendations for highly deviated wells and fields with greater well density are also discussed.
Optimizing Completions Cost by Using the Low Gravity Ball for Production Packer Setting Operations
Authors: Salami Hassannah , Ifediora Emmanuel , Numbere Otokini , Rahman Muhammed Abdul
Published: October 2018

The completion cost of development wells is usually 30-50% of the Authority for Expenditure (AFE). This depends on the number of zones to be completed, the completions strategy, cost of downhole jewelries and complexity. The quest to develop these complex un-stacked reservoirs has increased the tortuosity of the well plan and the complexity of the wells. This has in turn increased the completion complexity and has significantly increased the time taken to deploy the completion accessories, and the time taken to set the packer.

The sand management strategy and lower completion philosophy for the case study field, is setting Stand Alone Screens (SAS) as the lower completion assembly. Over the years, Addax Petroleum has used the metallic ball to set the lower completion production packer in a slightly straight well. Due to the need to optimize the well architecture and the tortuous profile of the well, the average production packer is now set at circa 80-85 degree's inclination. This optimization plan, significantly increased the amount of time required to circulate the metallic ball to the lower completion ball seat (a device engineered to aid the setting and hanging of the lower completion assembly in the production casing). This increase in time has further increased the completion costs.

To ensure that the development cost is reduced due to the current unstable and low oil price, a plastic setting ball (with lower specific gravity) was identified, risk assessed and used successfully to significantly eliminate the excess time for completion operations.

This paper reviews the challenges experienced using the metallic packer setting balls in highly tortuous horizontal wells. It also shows and discusses the huge cost savings achieved in case study wells where the low gravity packer setting ball was used to set the lower completions production packer.
Evaluation of a Depleted Oil Reservoir for Gascap Blowdown Using 3D Simulation Models: A Case Study of Chrome Field Development
Authors: Nwonodi Chike , Onwuchekwa Chukwuma , Ekong Inem , Amrasa Kefe , Osadjere Peter
Published: October 2018

Gas Cap Blowdown (GCBD) involves a process of depressurizing the gas cap of an oil reservoir to produce the associated gascap volumes, more often after the oil rim has been depleted of significant oil production. Thus, the optimal development plan for such reservoirs carries both large technical and commercial uncertainties and a robust technical evaluation is required to underpin commercial decision. In most moderate to strong aquifer drive reservoirs, the displacement of gas as the oil rim moves upwards into the gas cap causes residual oil losses with trapped gas.

This paper details the integrated study of a gascap development of oilrim reservoir initially developed by twelve (12) oil wells and with over 40 years of production history; and overlained with an undeveloped huge gascap with M-factor, m>1.6. The reservoirs comprise of number of communicating blocks by a series of nonsealing synthetic faults and a number of nonsealing transverse faults of up to 200 ft throw. Full scale 3-D simulation models; using the Shell's proprietary 3D dynamic modelling application; Modular Reservoir Simulator (MoReS) were deployed to assess subsurface uncertainties and history match reservoir performance of the reservoirs. The impact of resaturation of original gas cap volume and timing of gascap blowdown on the ultimate recovery of the gascap were exhaustively evaluated. Optimal development of the gascap was assessed against a range of technical uncertainties which then formed the basis for development of other reservoirs in the field that were not subject to the full uncertainty assessment.

From the results of the subsurface uncertainty analysis and extensive history match, three (3) gas wells targeting the gascap were proposed to develop the reservoir and optimum timing of gas cap development was evaluated, while concurrently producing the remaining oil volumes with exising wells. In addition, the results from sensitivity analysis evaluated different timing for commencement of gascap blow down and the associated incremental recoveries. Also, for residual oil in the presence of gas, reduced range of values upto 30% of the oil-to-water residual saturation results due to the different blow down timings.
Real Time Reservoir Management Successes at Sonam Gas Condensate Field, Offshore Nigeria
Authors: Eruvbetine Obor , Ogele Chile , Aitokhuehi Inegbenose , Charles Dawari , Onojeghuo Charles
Published: October 2018

Real Time Reservoir Management (RTRM) has as its foundation pillars real-time data acquisition, monitoring and surveillance. A fit-for-purpose real-time data acquisition, monitoring and surveillance program implemented at the Sonam Gas Condensate Field has led to considerable RTRM successes, resulting in a value capture of over $6.0 MM in a six-month period.

This paper discusses how RTRM was implemented in the Sonam gas condensate field, offshore Nigeria and how the availability of this data resulted in significant value capture. Setup was achieved with negligible incremental cost (~$0.003 MM) as existing control systems and Information Technology (IT) infrastructure provided the backbone for the system. Data from permanent downhole gauges (PDHGs) in the wells were linked to the platform Integrated Control System along with flowrates, pressures and temperatures from across the production platform. The data is then streamed to office locations via the existing network infrastructure for quality checks, interpretation and decision making.

The RTRM solution enabled the optimization of the completion program for the next set of development wells for the field. This was achieved using Pressure Transient Analysis on an existing well during several opportunistic shut-ins. This data would have been difficult and expensive to acquire given the commissioning and drilling activities that were ongoing. However, due to the real-time streaming and analysis, every production shut-in yielded value. The visibility of the data enabled, amongst others, real time decision making and intervention to ramp-up production, attainment of well target rates, calibration of flow rate meters and optimization of test separator operating parameters.

This paper demonstrates the tremendous value that could be created by implementing RTRM. The authors are convinced that the value demonstrated by Sonam RTRM reinforces the need for decision makers to ask, "why are we not implementing a fit-for-purpose RTRM in every producing asset"?
Simultaneous Flow Assurance and Production Optimization Using Chemical Paraffin Inhibition Method
Authors: Nwankwo Kenechukwu Obiajulu , Chikwekwem Chijioke James , Nwankwo Princess Christiana
Published: October 2018

This paper highlights efforts to eliminate wax production, by deriving a permanent flow assurance solution for a producing well and mitigate frequent downtime and expensive remediation operation.

In two case studies, the efficacy of a Paraffin dispersant was compared with that of a Paraffin inhibitor, with respect to a producing well's wax formation tendencies and characteristics with the view of optimizing well performance subject to chemical injectivity.

In the first case, well fluid was continuously treated with Paraffin dispersant to prevent wax deposition and subsequent blockage on the flowline but this effort proved ineffective because of periodic remediation. There was no significant performance improvement in this case.

In the Paraffin inhibitor case, an appreciable increase in pressure differential across choke was observed as well as significant production increase which improved with the treatment time of the well fluid with the paraffin inhibitor.

It was evident that Paraffin Inhibitor Injection was not just a flow assurance solution but also a production optimization tool. The project also saved the company about a million dollars annually, used for remediation of wax blockage on the flowline and sometimes sectional replacement of the flow line. Hence operation was a cost-effective method to achieve flow assurance and optimal production performance.