The objective of this work is to demonstrate that the choice of the conveyance method for Production Logging operations is key in horizontal wells, as it affects the flow dynamics and changes the well inflow performance compared to undisturbed flowing conditions. A case study is presented, showing that critical decisions to develop a field (or not) may have been wrongly influenced by Production Logging results, if the effects of the conveyance on the inflow distribution were not correctly understood.
Synthetic production logs and flowing pressure distributions along the horizontal section were computed, and sensitivities on conveyance method diameter (coiled tubing, tractor and cable), pipe diameter, well length and reservoir properties were also conducted. These results were compared with the normal well flowing conditions to establish the representativeness of the PL measurements. A method for simulating the undisturbed production profile is presented, which uses the results of a Multirate Production Logging and recomputed flowing pressures using nodal analysis.
The presence of the conveyance method alters the well's inflow performance and zonal contributions, due to the modifications of the flow geometry and additional frictional pressure drop. The bottomhole flowing pressure is disturbed, with lower pressures around the heel and higher towards the toe. The drawdown along the horizontal gets modified, acting as a preferential choke for production coming from the toe and increasing the driving force for production from the heel. The severity of the drawdown unbalance is a function of the induced frictional pressure, given by the pipe and conveyance diameter, well length, flow rates, etc. The simulations and sensitivities presented in this paper help to understand how significant the PL measurements are, and when these results become misleading. The case study supports these findings, where the pressure disturbance induced by the conveyance changed the flow distribution dramatically, wrongly indicating than an area of the field was relatively depleted compared to the zone around the heel. The lack of understanding of the impact of the conveyance method can lead to poor developmental decisions.
The application of real - time monitoring technologies presents a means to harnessing proactive or reactive controls in minimizing severity effects of slugging in the production system. This paper presents the development of a non-intrusive optical infrared sensing (NIOIRS) setup, for slug monitoring in pipes. The flow characteristics monitored were the development of slug flows and average phase fractions of gas and liquid in a vertical test section (0.018m by 1m) for superficial velocities of 0-0.131 m/s for water and 0 – 0.216 m/s for air. The measurement principle was based on the disparities in refractive indices of each phase in the sensing area. The sensing component of the sensor consisted of two pairs of IR emitters and photodiodes operated at wavelengths of 880 nm specifications. A circuit, for signal conditioning, amplification and data acquisition was set up to convert infrared light detected into voltage signals. Development of slug flow regimes was monitored from signal distributions binned under reference voltages. The transitions from bubble to slug flow, were observed at 10 percent count ratios of the signal distributions around typical sensor reponse for air. Validation from photos showed good agreements with the sensor response. A single peaked distribution around the reponse for water indicated bubble flow regimes, with the development of two peaks indicated increasing gas slugs for increasing superficial gas velocities compared to liquid slug in the pipe. Phase fraction results were interpreted from a derived calibration model, which was based on the average observed voltage and reference voltages of water and air over time. This model was compared with swell level changes, photographs and homogenous and drift flux correlation with agreement within +/-2 % for all flow regimes observed in the pipe. The Real-time application was carried out via the execution of an algorithm which incoprated the calibration information from the NIOIRS. The derived signals were processed and analysed onto a display in identifying slug flows development and phase fractions in real-time. A cheap and accurate sensing setup has been developed with the potential of real time monitoring of flow regimes and phase fraction detemination.
Makwashi, Nura (Division of Chemical and Petroleum Engineering, London South Bank University) | Sarkodie, Kwame (Division of Chemical and Petroleum Engineering, London South Bank University) | Akubo, Stephen (Division of Chemical and Petroleum Engineering, London South Bank University) | Zhao, Donglin (Division of Chemical and Petroleum Engineering, London South Bank University) | Diaz, Pedro (Division of Chemical and Petroleum Engineering, London South Bank University)
Curved pipes are essential components of subsea process equipment and some part of production pipeline and riser. So far, most of the studies on of wax deposition and the possible mitigation strategies have been carried out using straight pipelines, with little attention given to curved pipes. Therefore, the objective of this study is to use an experimental flow loop designed and assembled in the lab to study and understand the mechanisms and variable parameters that affect wax depositional behaviour under the single-phase flow. Series of experiments were carried out with pipes curvatures of 0, 45 and 90-degree at different flow rates (2 and 11 L/min). The sequence in which the bends are incorporated creates non-uniformity of boundary shear, flow separation, and caused isolation of fluid around the bends that affect wax deposition, which depends on flow regimes – Reynolds number along with the radius of curvature of the bend. Prior to the flow loop experiment, the waxy crude oil was characterized by measuring the viscosity, WAT (30°C), pour point (25.5°C), n-Paraffin distribution (C10 - C67), and the saturated/aromatic/resin/asphalte (SARA) fractions
Results of this study shows that the wax deposit thickness decreases at higher flow rate within the laminar (Re<2300) and turbulent (Re>2300) flow regimes. It was observed that the deposition rate was significantly higher in curved pipes, about 8 and 10% for 45 and 90-degree, respectively in comparison to the straight pipe for all flow conditions. Increase elevation of the curved pipe, however, led to a more wax deposition trend; where a higher percentage of wax deposit was observed in 45-degree compared to 90-degree curved pipe. This trend was due addition of gravity forces to the frictional forces - influenced by the physical mechanisms of wax deposition mainly molecular diffusion, shear dispersion and gravity settling. From the results of this study, a new correlation between wax deposit thickness and pressure drop was developed. A relationship was established between wax deposit thicknesses, bend angle in pipes and wax deposition mechanisms with a reasonable agreement with published data, especially for steady state condition. Therefore, this study will enhance the understanding of the wax deposition management and improve predictions for further development of a robust mitigation strategy.
Liquid loading phenomenon is known as the inability of the produced gas to carry all the co-produced liquid to the surface. Under such condition, the non-removed liquid accumulates at the wellbore resulting in reduction of the production and sometimes cause the death of the well. Several studies were carried out and correlation were developed based on field and experimental data with the aim to predict the onset of liquid loading in a gas well. However, each model provides different indication on the critical gas velocity at which the liquid loading exists. Thus, to have a clear understanding on the difference between most used models, experiments were performed in an upward inclinable pipe section. The 60-mm diameter test pipe was positioned at angles of 30°, 45° and 60° from horizontal. The fluids used were air and light oil. Measurements include fluid velocities and fluid reversal point. High-speed video cameras were used to record the flow conditions in which the onset of liquid loading initiated. Experimental results were compared with existing models by
A consortium of organizations has set out to tackle one of the more enduring challenges in the North Sea: the nondestructive testing (NDT) of corroded pipes under insulation and engineered temporary pipe wraps. General Electric has launched a subsidiary to develop and sell the use of flying, crawling, and swimming drones for inspections in the oil and gas industry, among others, the company announced.
An 18-month project will develop and trial a mobile robot for autonomous operational inspection of Total facilities. A consortium of organizations has set out to tackle one of the more enduring challenges in the North Sea: the nondestructive testing (NDT) of corroded pipes under insulation and engineered temporary pipe wraps. General Electric has launched a subsidiary to develop and sell the use of flying, crawling, and swimming drones for inspections in the oil and gas industry, among others, the company announced. Behind the use of most drones and unmanned aerial vehicles is the issue of safely and legally operating beyond the visual line of sight (BVLOS).
This paper describes a new direct electrical heating method in flexible-pipe systems. Medium-voltage electric heating systems offer reduced installation cost and increasing efficiency for multimegawatt oil and gas heating applications compared with low-voltage systems. For offshore applications, the systems offer the added benefit of both space and weight reductions.
The floating production, storage, and offloading (FPSO) facility Espirito Santo, located offshore Brazil in the Parque das Conchas (BC-10) field, is the world’s first turret-moored FPSO facility to use steel risers for fluid transfer. Steel catenary risers (SCRs) on a large-heave-motion vessel are susceptible to compression in the riser touchdown zone (TDZ). In this paper, a finite-element-analysis modeling method is presented to simulate deformation, pipe ovality, and local pipe buckling. Severe slugging is characterized by large pressure fluctuations at the base of the riser and is accompanied by fluctuations in fluid delivery from the top of the riser. This instability has negative effects on downstream equipment.
Majors BP and Chevron have overcome development challenges and delays to launch their respective Clair Ridge and Big Foot projects. This paper presents a case study that is an example of how reassessing a flow-assurance risk-management strategy for operating assets can identify opportunities for optimization. Banyu Urip crude contains 26% wax, which can lead to flow-assurance challenges in a crude pipeline exposed to lower temperatures. Current logistics and pipeline-infrastructure limitations make transportation and production of waxy crude oil challenging, necessitating a step change in the chemistry required to mitigate crude-oil-composition issues. Pipeline bottlenecks have created a wide gap in the price of gas at a key pipeline hub in the Permian compared to the US benchmark level.
An operator considered using Constant Bottomhole Pressure (CBHP) Managed Pressure Drilling (MPD) in the evaluation phase of a drilling project and decided not to go forward with MPD. While drilling the well, unfortunately, they had a well control event that required an increased mud-weight ultimately resulting in a differentially stuck-pipe condition.
MPD services were exclusively called to help free this differentially stuck pipe/BHA. MPD provided enough flexibility to deliberately reduce the wellbore pressure below pore-pressure and decrease the differential pressure to free the stuck pipe/BHA. Using CBHP variation of MPD resulted in unsticking the pipe as explained in this case history. The detected influx was circulated out with appropriate pump rate (high flow rate) using MPD equipment. The operator drilled forward with the assistance and additional protection of MPD to reach the Targeted Depth (TD) without having further issues in a very narrow drilling window. This successful field operation shows that CBHP MPD can indeed be used to precisely manage the annular pressures, as elaborated in the IADC’s MPD definition, and safely and successfully solve some of the baffling problems of the drilling industry.