ASCOMP support operators, engineering companies and equipment suppliers with technical studies and documentations within the Well & Petroleum Engineering discipline. We provide products and services that enable engineers to evaluate, complete and produce the energy at lower costs and reduced economic and environment risk. Our experts offer cutting-edge consulting services, covering various segments in the petroleum engineering for maximized asset value, including:
Drilling Production & Wells Design
- Mud, Polymers& CO2 injection See example
The context is of direct relevance to CCS or EOR; in the latter CO2 is injected in the well to boost the oil from the pores. The gas phase is initialized with volume fractions of 0.99 and 0.01 for CO2 and CH4, respectively. The liquid phase is initially composed only of H2O. The gas-liquid interfacial model does not include phase-change. The gas-phase components, however, can dissolve into the liquid following Henry’s law. The model using the level set technique to separate the water from the gas phases; the latter are treated separately by solving a transport equation for each of the species. The porous media is represented by an ad-hoc structure constituted by random cubical obstacles; it could have been similar to the array of cylinders presented previous to this section.
- Loss of drilling-fluids See example
Drilling fluid lost during circulation is one of production’s largest expenses and risks in terms of non-productive time and value of fluid lost. The objective of such study is to develop an understanding of the mechanisms of controlling the fluid flow of drilling mud in rock fractures with emphasis on characterizing the dependence on the non-Newtonian rheology. From the simulation, fluid rheological property requirements can be addressed to minimize drilling fluid loss.
Subsea Flow Assurance
- Hydrate formation and plugging See example
Plugging of flow-lines due to hydrate formation in subsea conditions (high pressure and low temperature) may be disastrous for flow assurance. A hydrate plug in a production line may indeed immobilize the production until it finally melts down (around a week time). Detailed simulation could anticipate or even prevent the formation of hydrates, or design strategies to ensure restarting after a long shutdown due to hydrate blockage. While 1D models for hydrate-plug formation in flow-lines are available and have been successfully applied for subsea tiebacks, full 3D CFD predictions are in fact rare in this area.
TransAT, specifically dedicated to N-Phase flow systems featuring complex fluid physics is now capable to predict wall adhesion of the hydrates and pipe plugging. The model has been used to predict hydrate induced plugging in prototypical canopies used today to collect spilled oil in the aftermath of a blowout. Selected results are shown in the figure above.
- Capping of subsea wells See example
Deep sea oil spills are a great concern today given the proliferation of oil production from wells at great depth. In the event of a spill, contingency plans including capping and collection have to be developed and validated. In particular, collection systems consisting of a simple dome and riser system can be critical in containing the environmental impact until a permanent solution such as a capping stack is operational. The current proof-of-concept study presents a full model to simulate the installation process of a dome over a spill with active mitigation, including accounting for hydrates formation and dissociation and hydrate adhesion. Active hydrates mitigation using methanol or hot water injection has been added to the modelling portfolio.
- Wax deposition
- Sand and particle erosion See example
Sand hold-up is a key hydrodynamic parameter for operation and control of multiphase production and pipeline transportation systems. TransAT’s suspension particle module predicts sand-laden flows under turbulent flow conditions, with specific models for deposition and re-suspension. One of the model combination used in TransAT is that meant to predict air-water-sand three-phase pipe flow, combining interface tracking methods with the Eulerian particle suspension field approach, as shown below. These TransAT simulations should help designers to advance their mechanistic approach for predicting local sand hold-up distribution and the subsequent effect on sand deposition during petroleum production and transport.
- Solid transport in pipes See example
Solid particles affect the flow performance of gas pipelines and may lead to severe corrosion and degradation of the pipe integrity. Black powder for instance is known to harm the valves and metering installations. New models have been developed in TransAT to predict the deposition and transport of clouds of particles. The models account for the complete physical mechanisms in play, including particle-fluid/turbulence interactions, particle-wall-particle interactions, particle settling and packing, concentration effects, agglomeration, etc.
We now are able to simulate the effects of varying different operational parameters on the critical mass flow rate of gas that can evacuate a bed of particles to avoid slug formation, and wash out the pipes.
Subsea flowlines and risers
- Flow in well bore and risers See example
Flow regime identification in vertical pipes (up to three main phases, plus when possible sand and hydrates) is the most critical issue for the success of drilling and production in a given well. If this is relatively well mastered in conventional drilling operations for small diameter risers (25-75 mm), the issue is becoming more and more complex for large diameter (D > 100mm) pipes, which today are used for non-conventional exploration conditions to respond to the depletion of hydrocarbon fields around the world.
Thanks to advanced models, TransAT can predict with high fidelity the topology of the multiphase flow, independently from the pipe diameter. The results (for a shorter length of the riser) can serve identify the flow regime, which is otherwise unknown for 1D codes like OLGA.
- Flow through downhole See example
Various experimental tests were conductedby major companies to evaluate perforator performance at field conditions. Small-scale laboratory test are still being questioned as to faithfully translating to downhole reality or not. General analytical models based on potential theory do not compare well with the calculated results of various downhole configurations: flow patterns differ considerably from those downhole, which could lead to erroneous interpretations of results and dynamic effects, such as cleanup. TransAT is now used to simulate the multiphase flow from the reservoir (using open pressure conditions) through a multiple perforation real-scale downhole.
- Gas lift See example
In the air-lift oil-extraction technique (upper image), gas is injected at the bottom of a hydrocarbon production pipe reducing the gravitational pressure drop in the well. With this, the produced oil flow rate in the pipe is increased. Gas lift is a widely employed Enhanced Oil Recovery (EOR) technique to boost production from depleted wells, and its efficiency could have enormous financial impacts. Gas is injected from valves of variable complexity attached to the pipe wall, which generates large bubbles.
- Flexibles lines
- Pipeline transport See example
Practical interests in the hydrocarbon transportation are wide, one of which being the stratified and the stratifying annular regimes featuring detached liquid droplets. In both cases, entrainment of droplets may occur and represent an important mechanism for transporting the liquid to the top of tube, affecting in turn the gas-phase mass flow rate.
The issue is addressed with TransAT, which proves very efficient in reproducing certain flow regimes with a detailed picture, like gas-shear induced surface deformations, wave formation, growth and breakup. Here too, a subtle model combination is needed, i.e. LES for the gas and liquid phases coupled at the interface, using Interface Tracking Methods for the interfacial dynamics.
- Coupling with 1D codes See example
3D CMFD is well suited for transient multiphase flow at the local scale where the flow is so complex that it is out of reach of 1D codes; e.g. flow in an elbow, separators, slug catcher, through the BOP or capping, junctions, well-heads, bottom wells, etc. Multiscale coupling is clearly needed, where 3D CMFD should deliver component-scale simulation results, providing information backward and upward to 1D codes. ASCOMP has already succeeded in coupling real-time and off-line 1D model OLGA with detailed 3D simulations using TransAT. The coupling schemes developed are generic enough to be applied to a variety of software, allowing bi-directional coupling between reservoirs, wells, pipes and surface network models. Work is in progress as to LEDAFLOW of Kongsberg.
- Flow through surface equipment
- Fluid separation See example
Primary oil/water separation is employed in oil industry to remove water from oil, which can be naturally present or injected to force oil to the surface. Both formation and injected water eventually arrive to the well bore and are produced at the well head. The bulk of suspended oil in produced water is free oil, and can be removed by means of gravity separation as the primary step of treatment. The separation process may not be as effective for emulsified hydrocarbons. Further, the presence of gas in the production stream from the wellhead generates a three-phase flow, which needs then to be separated into a gas phase for recovery, an oil phase for dehydration and transport, and a water phase for treatment.
The three phase flow is very complex, featuring all sorts of flow-regimes and characteristics: particles and sediment, drops, bubbles and interfaces, coalescence and emulsions. The complexity of the physics requires especially dedicated CFD software like TransAT that is capable to tailor predictive methods to the physics.
- Slug flow See example
Slug flow is a commonly observed pattern in horizontal and near horizontal gas-liquid flows. It is the regime with large coherent disturbances, causing large pressure fluctuations and variations in the flow rates that can affect process equipment’s. Intermittent appearances of aerated liquid masses fill the pipe cross-section entirely and travel downstream at high speed. Detailed CMFD studies using interface tracking as shown in the example below not only help determine global parameters such as slug speed and intermittency, but it also answers critical issues such as the flow transition and onset of sealing. Mitigation systems such as slug capture mechanisms are also designed using detailed CFD/CMFD.
- Floating devices
- Floating platforms
- Fixed platforms See example
Rogues waves approaching oil rigs can be devastating for the entire offshore platform. Waves exert tremendous unsteady loads on the rig, causing either the failure of pillars or in some cases the rupture of the under-water fixation cables. Today use is made of TransAT to predict the effect of various waves types, amplitudes and slopes over oil rigs, which could be of a very complex shape. The model can predict the pressure loads in steady and transient modes on the structure, in terms of pressure coefficients, or drag and moment forces. Thanks to its interface tracking versatile models, TransAT can predict with high fidelity the shape of wave forming and plunging over the rig.
- LNG Boil-off See example
- LNG transport i.e. sloshing
- Black-powder formation
- Subsea oil spill See example
The dramatic event of the Gulf of Mexico revealed a lack of understanding of flows subsequent to subsea hydrocarbon spills. Improving the realism and accuracy of predictions of these complex flow phenomena help define efficient mitigation operations required to minimize environmental consequences and costs for the operator and local businesses. The flows in question include multiphase flow jets, hydrate formation and dissolution, thermodynamics of hydrocarbon mixtures during fast pressure and temperature changes and transient interaction of plume constituents with the surrounding turbulence.
TransAT has proven robust in predicting a 3D unsteady multiphase plume in the aftermath of a hypothetical 1000m depth blowout. The five phases within the plume included water, gas, light oil components, heavy oil components and hydrates.
- Oil leaks dispersion in the sea See example