School of Egineering and Engineering Technology

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Open Access
Transport behaviour of xylene through compatibilized low density polyethylene composite
(U. P., 2017) Onuegbu, Genevieve C.; Onuoha, Chukwudike
The transport behaviour of xylene through compatibilized low density polyethylene (LDPE) composite was investigated at different temperatures 40 0C, 60 0C and 80 0C. The kola nut used was ground to 25 µm particle size. In preparation of the composite, 0 – 5 wt% of kola nut powder and 0 – 2.5 wt% of the compatibilizer were thoroughly mixed with 200g of low density polyethylene in an injection moulding machine. The injected LDPE/Kolanut composites were taken for sorption test. The sorption data obtained for the composite at different temperatures investigated were expressed as the mole percentage uptake, Qt (mole %). Results showed that the mole percent uptake of xylene at the five filler contents (0 – 5 wt%) generally increased with increase in sorption temperature but decreased with increase in compatibilizer and filler content. This can be seen at 80 0C and 0, 1, 1.5 and 2.5 wt% of the comptbilizer respectively. The molar percentage uptake of xylene at 1 wt% of the filler yielded the following values; 8.7876, 8.5962, 8.4056 and 8.3111 respectively. At 2 wt5, it yielded 7.9812, 7.9104, 7.7423 and 7.7199 respectively; at 3 wt% it gave 7.8232, 7.6351, 7.5663 and 7.4652 respectively; at 4 wt%, it yielded 8.4120, 8.3315, 8.2132 and 7.9667 respectively and at 5 wt% it gave 7.9635, 7.8630, 7.6256 and 7.5013 respectively
Open Access
A practical guide to site selection for communication antennas and their support structures in Nigeria
(SAVAP International, 2013-01) Agubor, C. K.; Ndinechi, M. C.; Opara, R. O.
Radio broadcasting and telecommunication transmitter stations should have their antennas properly positioned to make them capable of providing the required services. Suitable location of antenna structure will enhance signal clarity, wider coverage area and satisfactory reception of radiated signal. In most cases, engineering considerations in the determination of a station’s performance are treated analytically. However, it is important to know that the ability to serve large audience effectively and at the same time achieve wider signal coverage are greatly affected by the excellence of the transmitter location and its selection must be governed or influenced by experience with intangibles not subject to mathematical calculations. Field survey method was adopted by which information from the major radio and wireless Operators in the country was obtained. The paper therefore focuses on the various factors guiding the selection of suitable transmitter sites. It also presents a step-by-step guide and some important considerations to be taken into account from the planning to the site-acquisition stages. It recommends colocation of infrastructures which is an option not yet attractive to Service Providers in Nigeria.
Open Access
Design and implementation of a simple HMC6352 2-Axis-MR digital compass
(U. P., 2016-03) Agubor, C. K.; Ezeh, G. N.; Olubiwe, M.; Nosiri, O. C.
This paper deals with the design and implementation of a simple HMC6352 2-axis digital compass.Most compasses have been of the analogue type with magnetic needles as pointers. Replacing the “old” magnetic needle compass or the gyrocompass by an electronic solution offers advantages like having a solid-state component without moving parts and the ease of interfacing with other electronic systems. In this work, the aim is to design and implement a digital compass. To realize this, we made use of HMC6352 which is a 2-axis MR (magneto-resistive) sensor from Honeywell, Arduino Uno board with an onboard ATmega328 microcontroller chip, and a 16x2 character Liquid Crystal Display (LCD).We adopted the magneto-resistive (MR) technology as compared to flux-gate sensors common in most electronic compasses which has the disadvantage of making the device bulky. The trial test carried out with the completed HMC6352 digital compass showed a reading of 232.8 degrees West indicating its effectiveness in direction finding
Open Access
A review on gas well optimization using production performance models: A case study of horizontal well. Open Journal of Yangtze Gas and Oil, 3, 57 - 67
(Scientific Research Publishing, 2018-01-31) Igwilo, Kevin C.; Okoro, Emeka Emmanuel; Nwude, Anthony Afam; Mamudu, Angela Onose; Onuh, Charles Y.
This study considered the solution methods to determine optimal production rates and the rates of lift gas to optimize regular operational objectives. The foremost tools used in this research are offered as software platforms. Most of the optimization hitches are solved using derivative-free optimization based on a controlled well Performance Analysis, PERFORM. In line with production optimization goal to maximize ultimate recovery at minimum operating expenditure, pressure losses faced in the flow process are reduced between the wellbore and the separator. Nodal analysis is the solution technique used to enhance the flow rate in order to produce wells, categorize constraints and design corrective solution. A hypothetical case is considered and sensitivity analysis using the IPR Models for horizontal gas wells provides the effect on pressure and liquid drop out. The gas lift method is economically valuable as it produced an optimal economic water cut of 80 percent with 2 - 4 MM scf/day rate of gas injection; thus, 1800 - 2000 STB/day gas was produced.
Open Access
Drilling optimization on a new vertical exploration well designed for Niger Delta X-Field Reservoir
(ARC, 2018) Ossai, Patrick G. O.; Ohia, Princewill N.; Duru. Ugochukwu I.
There is no drilling optimization without proper well planning. This research looked at optimal exploratory well design possibilities for two reservoirs (A and B) located within a Niger Delta X-Field, south of Nigeria. After much data analysis from both reservoirs the researchers concluded that reservoir A is a gas reservoir and reservoir B is an oil reservoir. Well design work was discontinued for reservoir A (the gas reservoir) because there are no gas facilities in place to transport and distribute possible gas production. Our research team carried out further analysis and completed the well design for optimal oil production from reservoir B (the oil reservoir). This study is inclusive of graph(s), well design assumptions, relevant equations and applicable calculations used in generating our design results (as summarized in a table). Various schematics to illustrate our optimal well design are also provided.
Open Access
Development of proxy model for production forecast using adaptive neuro-fuzzy inference system and experimental design
(Inderscience Enterprises Ltd., 2015) Arinkoola, Akeem Olatunde; Duru, Ugochukwu I.; Onuh, Haruna Monday
Proxy-models are computationally cheap alternative to full numerical simulation during production performance predictions. They are widely use in reservoir management to forecast production in order to assist investment decisions. However, the underperformance of many E&P projects is due to unrealistic forecast quantities arising from assumptions, human biases and reservoir modelling limitations. Hence, considerable efforts are needed to bridge gaps between forecasts and the actual production. The reservoir under study is developed with six producing wells, all deviated. The internal reservoir heterogeneity believed to have created significant fluid flow anisotropy which trapped the remaining mobile oil in the compartments poorly contacted by the current producing well spacing. Consequently, the proposed reservoir management is Infill drilling. This study utilised simulation model for well selection and its optimal placement within the reservoir. Experimental design technique and adaptive neuro-fuzzy inference system (ANFIS) were integrated to develop predictive model for production forecast given new development option. Comparison of the conventional response surface (RSM) and ANFIS models was made based on their prediction performances. The ANFIS model was found to be superior.
Open Access
Well productivity enhancement using matrix acidizing-a Niger Delta case
(2015) Ohia, Nnaemeka; Igwilo, K; Duru, U
As a result of the rapid reduction in productivity of well B14, south west of the Niger Delta region, the need to investigate the cause of the damage was initiated. When it was identified fine migration as the major cause of the production decline, acid stimulation was recommended as the mitigation strategy. Acid (matrix) stimulation practice involves the pumping of acid into the formation through the wellbore at the rates and pressures below the fracture gradient of the formation. Conventionally, hydrochloric acid (HCL) is used for carbonate formations while hydrofluoric acid (HF)/ mud acid (HCL +HF) is best suited for sandstone formations. Also, in a very high damaged formation and very high temperature environment that requires prolong contact of the HCL acid with the steel pipe, due to the severe corrosion that will occur, organic acids are more suitable. In stimulating this well, mud acid was used and the well was stimulated using organic mud acid or organic clay acid. Stimulating this well led to a total incremental production gain of over 485 BOPD (150% gain) however a corresponding reduction in skin was not observed This paper reviews and highlights the operational best practices as utilized in this project as well as the potential cause for an increase in skin even after a stimulation job.
Open Access
In-situ combustion: Reservoir candidacy/project selection criteria(s) for Niger Delta heavy oil reservoirs
(2018-09) Ossai, Patrick Godwin Oyindobra; Duru, Ugochukwu Ilozurike; Obah, Boniface; Ohia, Princewill Nnaemeka
There is a drastic need for the oil companies operating within the onshore(s) and offshore(s) of Nigeria to critically start looking at the various possibilities of heavy oil production from the nation’s various fields located in the Niger Delta region using already available Enhanced Oil Recovery techniques/methods such as In-situ combustion (ISC), CHOPS and SAGD. This study focused on In-situ combustion as a means of enhancing likely heavy oil production in the Niger Delta using the Nelson & McNeil 1961 ISC model. The study developed applicable screening criteria(s) for both reservoir candidacy and ISC project selection in the Niger Delta. Corresponding programs and flow-charts that would allow petroleum engineers in the Niger Delta to theoretically evaluate production erformances using his/her computer(s) was also developed. It was discovered also during our course of work that all six reservoirs considered in both Case 1 (Venezuela reservoir) and Case 2 (Niger Delta reservoirs) met this study’s reservoir candidacy selection criteria(s) for possible applicability of an ISC project performance evaluation(s) with respect to enhancing oil production. These reservoirs were further graded / ranked based on their theoretical ISC project performances as calculated and evaluated using a well known ISC model as documented in the ISC handbook.
Open Access
Geomechanical principles of hydraulic fracturing method in unconventional gas reservoirs
(Kambohwell Publisher Enterprises, 2018-05) Unwana, Solomon Anwana; Ossai, Patrick Godwin Oyindobra; Duru, Ugochukwu Ilozurike; Ohia, Princewill Nnaemeka ,; Selegha Abrakasa
Unconventional gas production from shale formation is not new to oil and gas experts worldwide. But our research work was built around hydraulic fracturing technique with focus on the Perkins Kern-Nordgren (PKN) 1972 hydraulic fracturing model(s). It is a very robust and flexible model that can be used on two major shale reservoirs (with the assumption of a fixed height and fracture fluid pressure). The essence was to compare detailed geo-mechanical parameters extracted from wire-line logs with Perkin-C model to select the right well as candidate for simulation. It aided in the prediction production of shale gas from tight shale formations. These also helped in reviewing safe and economical ways of obtaining clean energy sources. Based on similarities in well and formation properties our research team subjected IDJE-2 well (located in the Agbada shale Formation of Niger Delta, Nigeria) to various conditions, equations and assumptions proposed by the study model while also validating our results with the PENOBSCOT L-30 well, located in Canada (with existing profound results from stimulations). The PENOBSCOT L-30 well (Case 1) and IDJE-2 well (Case 2) were both subjected to same conditions, equations and assumptions as applicable to the study model to enable us compare and evaluate stimulation performances. But both cases tend to react differently. However the fluid behavior at constant injection time increases at about 99.64%. Whereas, the maximum width at wellbore shows that a constant increase of fracture width will yield an increase in propant permeability, tensile strength and Poisson’s ratio for Case 1 & 2. Our research results show how rock properties can affect fracture geometry and expected production rates from stimulated shale
Open Access
Hydraulic evaluation of drilling fluid performance on hole cleaning for different rheological models
(Society of Petroleum Engineers, 2005-08-03) Duru, Ugochukwu; Chukwu, Godwin A.; Obah, Boniface
Bottom hole cleaning is an important function of drilling fluid that needs special attention during a drilling operation. Good hole cleaning results in an increase in penetration rate and, at the same time, reduces the operating drilling cost. One of the effective steps towards reducing operating cost is to have a well designed drilling hydraulics program that will optimize the energy used at the mud pumps. A variety of hydraulic optimization designs are available depending on the cutting structure and the formation to be drilled but a common objective is to maximize the available hydraulics to provide optimum hole cleaning. Many authors have discussed various ways of effecting proper hole cleaning using different approaches and methods. Fluid velocity, pump rate, fluid rheology, drill pipe eccentricity, pipe rotation and particle settling velocity, among others were used at various times to evaluate effective hole cleaning. The economic appraisal of hole cleaning using hydraulic horsepower and jet impact force by Wright et al (2003) have proved that both can be used for the design of optimum hydraulic programs on the basis of minimum drilling cost. In this study, basic hydraulic models for vertical oil wells were used to determine the pressure drop in a drill string circulating system and hence, the equivalent circulating density (ECD) using both the Bingham plastic and Power law fluids’ rheological models. From the slip velocity relationships, the transport efficiency of the cuttings for both models was determined. An economic evaluation of the hydraulics from the energy and horsepower requirements for both models showed that the power law fluid model provided a better transport efficiency, and hence more economical in terms of minimum drilling cost.
Open Access
Reliability evaluation of onitsha power distribution network via analytical technique and the impact of PV system
(U. P., 2014-06) Izuegbunam, F. I.; Uba, I. S.; Akwukwaegbu, I. O.; Dike, D. O.
This paper evaluates the Reliability of Onitsha power distribution network using analytical technique and the level of improvement achievable through application of photovoltaic (PV) system at injection substations. ETAP simulation software was used to run the power flow and reliability assessment of the Network. The investigation revealed that before the PV installations the total revenue lost due to outages in 2009, 2010 and 2011 amounted to N17,439,247,940; N28,718,370,004 and N61,131,521,807 respectively. Whereas after the PV installation the total revenue lost reduced to N6,769,656,987, N12,718,370,004 and N21,359,660,013 respectively representing 61.2%, 55.7% and 65.1% reduction in revenue loss for the period under review.
Open Access
Dynamic security assessment of 330KV Nigeria power system
(U. P., 2012-07) Izuegbunam, F. I.; Ubah, C. B.; Akwukwaegbu, I. O.
The security of power system operation is a measure of its reliability; hence the planning and real-time operation of power system requires regular security assessment. This paper presents a dynamic security assessment of the Nigeria 330 kV power network. It considered the installed capacity of the power system alongside the available capacity as well as network structure in terms redundancy for flexibility. Some weak areas of the system were identified and the security status of the network assessed under large disturbance condition. Results match expectations as the system’s response to impressed contingencies were discussed. Feasible corrective measures proffered for improved system’s security.
Open Access
Load flow control and analytical assessment of voltage stability index using thyristor controlled series capacitor (TCSC)
(U. P., 2014-04) Akwukwaegbu, I. O.; Okwe, Gerald Ibe
- Voltage stability problem has become one of the major concerns in the operation of power system in recent years. The reason is that power systems all over the globe are being operated with reduced margins because of the exponentially growing demands and the associated stress on the power transmission resources aggravated by a general reluctance to invest in improvement of the electric grid infrastructure. Moreover, voltage instability has been responsible for severe network collapses world-wide and subsequently, the possible threat of voltage instability is becoming more pronounced in power utilities. In order to avoid the voltage collapse, this paper presents maximum loadability identification of a load bus in a power transmission network which is achieved by performing voltage stability study by utilizing Fast Voltage Stability Index (FVSI) as an indicator of the maximum loadability termed as Qmax. In this technique, reactive power loading will be increased gradually at particular load bus until the FVSI reaches close to unity. Therefore, a critical value of FVSI was set as the maximum loadability point. This value ensures the system from entering voltage-collapse region. The main purpose in the maximum loadability assessment is to plan for the maximum allowable load value to avoid voltagecollapse; which is important in power system planning risk assessment index. In order to improve the system stability, Thyristor Controlled Series Capacitor (TCSC) is installed in the most severe line, which is identified from the line stability index values of all lines in a system. TCSC is a series compensated device used for voltage stability enhancement, which is to be connected in series with transmission line. It can control the transmission line impedance to improve the line transfer capability and to regulate the receiving end bus voltage. This proposed technique was applied to solve real problems in a 14 bus power grid using Power flow analysis. Power flow is very necessary for planning, operation, economic scheduling and exchange of power between utilities. Newton Raphson iterative algorithm is used for solving the power flow problems due to its ability to converge very fast with small number of iteration. Simulation of power flow solutions with and without TCSC was done using MATLAB 7.5 program. The result shows that the application of TCSC improved the voltage profile of the system and furtherly enhanced the power flow.
Open Access
Water flooding process of oil recovery in the Niger Delta region of Nigeria
(U. P., 2020) Chikwe, A. O.; Duru, U. I.; Obasi, E. C.
Water flooding is a process of hydrocarbon recovery where water is injected through injection wells into the reservoir to recover oil from the production well. It is usually injected in a reservoir rock that has fluid communication with the producing reservoir. Waterflooding is secondary recovery mechanism whose purpose is to maintain and support reservoir pressure thus displacing hydrocarbon towards the producing wellbore. In this study a reservoir in the Niger Delta, Reservoir OZ-70 is used for evaluation and economic analysis of the water flooding project using five spot pattern. Reservoir OZ-70 had oil at the start of the flood to be 2.38MMSTB. The reservoir was left depleted with the unrecovered oil in it. But based on the analysis carried out on secondary oil recovery by water flooding, 0.98 MMSTB was recovered from 2.38 MMSTB about 41.1% at a breakthrough period of 428 days. When water viscosity was increased from 0.60 to 0.65, 0.99MMSTB about 41.7% was recovered. Economic evaluation of the reservoir oz-70 water flooding project was also performed. Net present value (NPV) was calculated to be $8.74million while internal rate of return (IRR) at a discount rate of 10% was 126.3%. Therefore, since the NPV is greater than zero and IRR greater than hurdle rate (10%) the project is economically viable.
Open Access
Enhanced recovery of heavy oil in the Niger Delta: Nelson and Mcneil model a key option for In-Situ combustion application
(Canadian Research & Development Center of Sciences and Cultures, 2025) Ossai, Patrick G. O.; Ohia, Princewill N.; Obah, Boniface; Duru, Ugochukwu I.; David O. Onaiwu
In-situ heavy oil recovery involves several field tested enhanced oil recovery methods/techniques with applicable models. Such field tested techniques include non-thermal oil recovery, hybrid oil recovery and solvent-base oil recovery. The viabilities and field successes recorded by these in-situ heavy oil recovery techniques/methods cannot be overemphasized. But, the main focus of this study is on heavy oil recovery using in-situ combustion with attention on the application of Nelson and McNeil model as documented in the in-situ combustion handbook (Partha, 1999). We subjected data(s) obtained from five (5) heavy oil reservoirs located within the same field in the Niger Delta to the correlations, equations, assumptions and calculations proposed by our study model. This enabled the research team to carry out performance evaluations while considering in-situ combustion implementation using our proposed model. Our result outcomes were further validated with a foreign heavy oil reservoir having similar reservoir properties. Our study results show how viable and profitable (with possible commercial production) heavy oil production from unconventional reservoirs in the Niger Delta would be. Currently, most of the internally generated oil revenue by the Nigeria government is from cheap/light oil obtained from conventional reservoirs (which is fast declining globally).
Open Access
Optimum tubing size prediction model for vertical multiphase flow during flow production period of oil wells
(Springer, 2020-10-04) Nwanwe, C. C.; Nwanwe, U. I.; Nwanwe, O. I.; Chikwe, A. O.; Ojiabo, K. T.; Umeojiako, C. T.
Optimum tubing size (OTS) selection was traditionally done by using nodal analysis to perform sensitivity analysis on the different tubing sizes. This approach was found to be both cumbersome and time-consuming. This study developed a user-friendly and time-efficient OTS prediction computer model that could allow Petroleum Production Engineers to select the best tubing size for any vertical oil well. The tubing size selection was based on the present operating low rate, economic considerations and future operating low rate as defined by the OTS selection criteria of this study. The robustness of the model was tested using tubing sizes ranging from 0.824 to 6.0 inch in a vertical well producing from both saturated and undersaturated oil reservoirs. The 2.750-inch tubing was found the OTS for both scenarios. In the validation, the results obtained from the novel OTS prediction model and Guo et al. (Petroleum production engineering: a computer-assisted approach, Gulf Professional Publishing, Cambridge) spreadsheet program using the Pettman–Carpenter method were in excellent agreement for operating low rate but not for operating pressure. Furthermore, the novel OTS prediction model was in excellent agreement with the same spreadsheet program based on modified Hagedorn–Brown correlation for both operating fowl rate and pressure. The results showed that the model developed in this study is reliable and can be used in the field for vertical oil wells. The new model could as well inform the Production Engineer when the well would need artificial lifts for economic production of the well. It was recommended that Newton–Raphson and modified Hagedorn–Brown methods be used in future study.
Open Access
A Novel approach to estimation of leak location in an oil pipeline
(U. P., 2015-08) Obibuike, U. J., Obah, B., Aboniyi, C., Anyadiegwu, C. I. C. & Ogwo, O. U. J
This paper presents various approaches to the location of leak in an oil pipeline. However these approaches are based on the available input data for the leak location study. The first approach is the hydraulic gradient intersection approach using Pipes and Excel worksheet. This method relies on the expectation that a leak disturbance settles out eventually to a new Steady-state position. The second approach utilizes a new concept of flow through an orifice and liquid relief through a valve to evolve a criterion for elapsed leak time in an event of a leak as well actual leak time to determine leak location. Orifice area was determined through a liquid relieving scenario and back-pressure at the point of leak assumed to be at atmospheric pressure. A set of mathematical equations were developed and integral solution of the form function of a function was used to solve the resulting differential equation describing the depressurizing process. The model was however validated using a pipeline profile data of a pipeline X which has suffered spill in time past at Niger Delta region where it performed well. The two approaches vary in their input data requirements as mentioned before. Key inputs to the former are the input and output flow conditions of temperature, pressure and flow rate while the latter requires the time (shut-in time and time of leak). Key outputs are the rate variation of flow rates against leak location.
Open Access
Advances in well design
(SAVAP International, 2013) Kerunwa, Anthony, Fekete, P. O. & Anyadiegwu, C. I. C.
Modern drilling technologies are emerging progressively to meet current challenges in well operations. Operators are going into much more complex environments, and drilling conditions become much tighter. Conventional well designs are no longer able to handle these new environments. The result is increased drilling costs, Non Productive Time, hole collapse, etc. While well engineers are worried by these developments, the busy schedule of most companies does not give room for delegating staff to proper study and research as to implement recent improvements into pre-drill plans. In some cases, economics may not favour adoption of new drilling methods as well. This work is a review of selected advances in well design available to oil industries today. Particularly emphasis was laid on the well design aspects of Drilling with Casing (DWC), Managed Pressure Drilling (MPD), Solid Expandable Systems, Air drilling and Geo mechanical Modelling for wellbore stability. To show the benefits of these advanced well design applications, case studies from different well operations have been presented. The yardstick for measuring these benefits is conventional drilling and well designs methods. While these results might not have covered all areas of improvements in well design, it is expected that this review will provide oil companies with an idea of trends in well design and areas for improving drilling performance at various operational levels. Hole problems will be minimized by such large margins that cost savings in drilling budget becomes significant. Reoccurrence of well problems may be minimized.
Open Access
Performance evaluation of a biomaterial in an aqueous based drilling mud at high pressure high temperature
(Canadian Research & Development Center of Sciences and Cultures, 2019) Duru, U. I.; Onyejekwe, I. M.; Uwaezuoke, N.; Isu, D. O.
Oil reserves are found in deep formations where the conditions of temperature and pressure are always high. These conditions have direct effects on the rheological properties of drilling fluid as they vary with increasing temperatures and pressures. Two sets of experiment were carried out on weighted and unweighted mud samples at a temperature of 250o F and 500psi pressure. The presence of locally sourced additives helped the mud to remain pseudoplastic at these conditions and also retained essential properties of the mud need for drilling operations. The plastic viscosities of the weighted and unweighted mud were 36cP and 27cP respectively. The yield stresses were 149lb/1002 ft and 110lb/1002 ft for the weighted and unweighted samples while the fluid loss volumes were approximately equal. The thickness of the cake for the weighted sample is 3.7mm and 4mm for the unweighted sample. The weighted sample with a reasonably higher PV has a better hole cleaning ability than the unweighted sample. Mucunna Solannie performed excellently to retain the essential properties of these formulations at 250o F and is therefore recommended as a HPHT drilling mud additive.
Open Access
Reduction in annular pressure loss by mud rheology control-a means of mud pump pressure optimization: A case study of a Niger Delta Well
(International Knowledge Press, 2016-02-18) Onugha, Ifeyinwa N.; Igwilo, Kevin C.; Duru, Ugochukwu I.
This paper proposes two linear mathematical models for the reduction of annular pressure loss in a Niger Delta well- X, so that mud pump pressure is optimized. Data related to mud rheology, mud pump pressure, drill cuttings and the well geometry is available for well X which has already been drilled. The first linear model involves the reduction in pressure drop in the drill collar-casing annulus and the second linear model involves the reduction in pressure drop in the drill pipe-casing annulus. These models express reduced or critical annular pressure drops in terms of two mud rheological parameters- the yield point and plastic viscosity. For combined annular drill collar and drill pipe pressure loss, this paper proposes that the two linear mathematical models can be solved simultaneously to obtain optimum yield point and plastic viscosity of the drilling mud system to be employed for hole cleaning in the combined drill collar-casing and drill pipe-casing annulus. The HerschelBulkley model is employed as the rheological model that represents the properties of the drilling mud system analyzed and is generated for eight rheological cases each of the drill collar and drill pipe annular hole cleaning as well as two cases of the combined drill collar and drill pipe annular hole cleaning.