Idoko Job John

This report presents an analysis of three natural gas pipeline transmission scenarios through a distance of 342Km, from Escravos to Lagos, given conditions of 70barg Maximum Allowable Operating Pressure (MAOP) at Escravos terminal and a minimum delivery pressure of 45barg at Lagos.

To begin, the maximum pipeline capacity at the given operating constraints was estimated from a simple model built with a single pipeline network, process stream properties and other necessary model input parameters. Afterwards, a technical analysis was carried out for the requirements and feasibility of expanding the gas network by an extra 300mmscfd and 600mmscfd with two expansion options: using compressor stations to provide the additional pressure that will be required for the expansion and using pipeline looping to reduce pressure drop along the original pipe such that the 70barg MAOP and 45barg delivery pressure were adhered to. Finally, an economic comparison was made between the two pipeline expansions options mentioned above.

Results showed that a maximum pipeline capacity of 625mmscfd will be required for the first task. Furthermore, the 300mmscf expansion will require one compressor station of 2818.94hp rating or a 243Km length of reinforcement while the 600mmscfd expansion will require two compressor stations of a total rating of 4523hp or a reinforcement pipe length of 335kKm for the use of compressor stations or pipeline looping respectively.

Economic analysis revealed that gas network capacity expansion was found to be significantly more expensive if pipe looping is used relative to the use of compressor stations as the overall cost, for both 300mmscfd and 600mscfd extra gas network expansion by looping exceeds the cost of using compressor stations by £187.62 million.

Given various competing alternatives, the rigorous evaluation of development options for oil-rim reservoirs can be challenging and computationally intensive. For quick and robust decision-making, an efficient screening method that accounts for the relevant static and dynamic properties of the reservoir of interest is desirable. Based on controlled numerical simulation experiments, this paper proposes simple screening guidelines for oil-rim reservoirs under the mutually exclusive development scenarios of (i) sequential oil-then-gas (OTG); (ii) concurrent oil-and-gas (COG); and (iii) gas-only development (GOD). For simplicity, a two-level factorial design was used to create 17 experiments from a set of static and dynamic reservoir properties. A generic reservoir box model was then developed and used to conduct a total of 51 experiments. For each of the three development options, normalised surrogate models were developed for hydrocarbon recovery factor (RF) as a function of these static and dynamic properties. For the specific box model and the parameter space examined, it was found that the performance of the OTG option is most sensitive to oil API (viscosity), vertical anisotropy, oil relative permeability and liquid offtake rate. The COG case showed oil API, vertical anisotropy, liquid offtake rate and oil relative permeability as the heavy hitters, while the GOD option returned oil rim thickness, relative permeabilities and gas offtake rate as the key drivers of reservoir performance. Performance comparison of the three development options reveals that when reservoir properties are favourable to oil flow, OTG is the preferred oil-rim development option, while the GOD option is the most attractive when the reservoir is naturally less favourable to oil mobility. Although these guidelines provide indications of the most promising option, the final decision should be premised on further detailed studies, while considering both technical and non-technical factors that are peculiar to the specific project in question.

Despite the recent wide embrace of mechanical descaling approaches for cleaning scales in petroleum production tubings and similar conduits with the use of high-pressure (HP) water jets, the process is still associated with downhole backpressure and well integrity challenges. While the introduction of sterling beads to replace sand particles in the water recorded high successes in maintaining well completion integrity after scale removal in some recent applications of this technique, it is, unfortunately, still not without questions of environmental degradation. Furthermore, the single nozzle, solids-free, aerated jetting descaling technique – recently published widely – is categorized with low scale surface area of contact, low descaling efficiency and subsequent high descaling rig time. The modifications to mechanical descaling techniques proposed in this work involve the use of three high-pressure flat fan nozzles of varying nozzles arrangements, standoff distances and injection ...

As an alternative to the construction of new infrastructure, repurposing existing natural gas pipelines for hydrogen transportation has been identified as a low-cost strategy for substituting natural gas with hydrogen in the wake of the energy transition. In line with that, a 342 km, 36″ natural gas pipeline was used in this study to simulate some technical implications of delivering the same amount of energy with different blends of natural gas and hydrogen, and with 100% hydrogen. Preliminary findings from the study confirmed that a three-fold increase in volumetric flow rate would be required of hydrogen to deliver an equivalent amount of energy as natural gas. The effects of flowing hydrogen at this rate in an existing natural gas pipeline on two flow parameters (the compressibility factor and the velocity gradient) which are crucial to the safety of the pipeline were investigated. The compressibility factor behaviour revealed the presence of a wide range of values as the propor...

As an alternative to the construction of new infrastructure, repurposing existing natural gas pipelines for hydrogen transportation has been identified as a low-cost strategy for substituting natural gas with hydrogen in the wake of the energy transition. In line with that, a 342 km, 36″ natural gas pipeline was used in this study to simulate some technical implications of delivering the same amount of energy with different blends of natural gas and hydrogen, and with 100% hydrogen. Preliminary findings from the study confirmed that a three-fold increase in volumetric flow rate would be required of hydrogen to deliver an equivalent amount of energy as natural gas. The effects of flowing hydrogen at this rate in an existing natural gas pipeline on two flow parameters (the compressibility factor and the velocity gradient) which are crucial to the safety of the pipeline were investigated. The compressibility factor behaviour revealed the presence of a wide range of values as the propor...

The common practice of using chemicals and solid-entrained liquids to remove soft scales in production tubings is associated with a high risk of contaminating the environment and eroding pipe internal surfaces. Due to the suspended solids, the current practices are also characterized by high pumping costs and are more problematic to rotating parts of machinery than freshwater. As a cheap and less risky alternative to these corrosive chemicals and liquids, this paper investigates the feasibility of utilizing multiple high-pressure (HP) water jets for the same objective. A total of 54 experimental trials were conducted to study the effects of four factors on the efficiency of scale removal with multiple flat-fan nozzles at an orientation of 25°. The factors investigated are (1) number of nozzles; (2) spray injection pressure; (3) stand-off distance between the spray nozzle and target scale; and (4) condition of the production tubing: ambient and pressurized. Details of the experimenta...