Characterization of the rock and fluids is an essential step in screening a reservoir for Low-Salinity Water Flooding (LSWF). A detailed characterization of rock and fluid properties using appropriate methods is being presented for LSWF in a low-permeability deep carbonate reservoir together with a critical analysis of findings. The techniques used are assessed against other possible alternative methods, with inferences drawn on advantages and disadvantages of each to better interpret and apply data so gathered. In so doing, discussions on their key features as to how they can be used effectively and efficiently to screen a reservoir for LSWF are also provided. Such integration of results with other available reservoir and production data should result in a comprehensive description of the target reservoir, and it will help interpret the mechanisms and process dynamics more reliably during a low-salinity waterflood. This integration should allow us not only to gain confidence on the experimental studies but could also help optimize the key parameters responsible for formulating a more robust, reliable and representative regime for tests relevant to the LSWF prior to its eventual implementation in the field. To authors’ knowledge, such integration of experimental studies has not yet been reported in the literature, particularly for the tight carbonate reservoirs with highly paraffinic oil.

Hydrate is ice-like solid non-stoichiometric crystalline compound, which is stable at favorable low temperature and high-pressure conditions. The predominant gas component stored in naturally-occurring hydrate bearing sediment is CH 4 and is estimated about 3000–20000 trillion cubic meter worldwide. Thus, it has attracted significant research interests as an energy source from both academic and industry for the past two decades. Ensuring drilling safety is much important to realize efficient exploitation of hydrate source. Additionally, accurate prediction of wellbore temperature field is of great significance to the design of drilling fluid and cement slurry and the analysis of wellbore stability. However, the heat transfer process in wellbore and hydrate layer during drilling through hydrate formation is a complex phenomenon. The calculation method used in the conventional formation cannot be fully applied to hydrate reservoir drilling, largely due to the complex interactions between the hydrate decomposition, multiphase flow and heat transfer behaviors. In this study, an improved thermal model of wellbore for hydrate layer drilling process is presented by coupling the dynamic decomposition of hydrate, the transportation of hydrate particles in cuttings and heat transfer behaviors in multiphase flow. The distribution of temperature field and rules of hydrate decomposition both in wellbore and hydrate layers are thoroughly analyzed with case study, which is very helpful for the designing drilling parameters, avoiding the gas kick accidents. As well as making a detailed guidance of wellbore stability analysis. This proposed mathematical model is a more in-depth extension of the conventional temperature field prediction model of wellbore, it can present some important implications for drilling through gas–hydrate formation for practical projects.

Subsea Wellheads are the male part of an 18 3/4” bore connector used for connecting subsea components such as drilling BOP, XT or Workover systems equipped with a female counterpart — a wellhead connector. Subsea wellheads have an external locking profile for engaging a preloaded wellhead connector with matching internal profile. When the connector is locked subsea a metal-to-metal sealing is obtained and a structural conduit is formed. The details of the subsea wellhead profile are specified by the wellhead user and the standarisedH4 hub has a widespread use. In terms of well integrity, the wellhead connector is a barrier element during both well construction (drilling) activities and life of field (production). Due to the nature of subsea drilling operations a wellhead connector will be subjected to external loads. Fatigue and plastic collapse are therefore two potential failure modes. These two failure modes are due to the cyclic nature of the loads and the potential for accidental and extreme single loads respectively. Establishing the safe load level that the wellhead connector has structural capacity to handle without failure can be done by deterministic engineering methods. Similarly, a deterministic calculated safe fatigue life is the use limit preventing fatigue failure, assuming no inspections. Probabilistic engineering method; Structural Reliability Analysis (SRA), can be applied to a subsea wellhead connector to establish the probability of fatigue failure (PoF). Risk Based Inspection (RBI) is a probabilistic analysis procedure that requires quantified PoF and Consequence of Failure (CoF). The RBI outcome may be used to optimized inspection plans to ensure a safe PoF target level. The RBI methodology is widely accepted, and guidance can be found in several standards. Subsea wellheads are normally classified as un-inspectable. During drilling operations commencement, the uppermost section of the wellhead (high pressure housing including H4 hub profile) will be visible and accessible thus allowing for inspection. This uppermost section may also accessible for inspection when a wellhead connector is locked on. From an SRA basis a generic RBI procedure applicable to subsea wellheads are proposed and established for a generic case of a 27” mandrel with a H4 hub. This paper then proceeds to providing the maximum non detectable flaw size performance required for a wellhead inspection tool/method to be efficient. The importance of accidental load and cyclic load magnitude and uncertainty is shown to impact this conclusion. The potential inspectional value of performing BOP connector leak test at regular intervals during the drilling operation has also been investigated and shown to be conditionally limited. This paper proposes a procedure for application of RBI to the problem of achieving life extension of a wellhead external locking profile while connected to a wellhead connector. The objective is to propose minimum performance requirements for the inspection tool/method to be efficient. Finally, the potential impact of RBI results in a well integrity risk assessment is covered.

In a subsea production environment, a HIPPS (High Integrity Pressure Protection System) is used to operate the system at a design pressure lower than the Shut-in tubing pressure. It helps maintain high reliability against overpressure or burst scenarios. This paper introduces a subsea HIPPS system and its application principle. It also discusses how HIPPS can be an enabler for developing high pressure remote or stranded fields. Furthermore, it discusses the perceived hardware/project cost reduction benefits, which may or may not be available or are insignificant. From experience on multiple field development projects, HIPPS is an enabler for connecting differently rated systems; however, monetary savings are not a given and vary from field to field. Attention must be given to total installed costs of the system before associating monetary gains with the introduction of HIPPS. The content and scenarios presented in this paper pertain to deep-water field developments.

Model ice testing is the state of the art validation and testing method for ships and structures interacting with ice. Its initial design objective was the prediction of resistance forces of ice breaking ships by using Froude and Cauchy similitude to account to the most significant force ratios. In the ice breaking process the forces due to downward bending are considered most significant and therewith much emphasis was spent on the correct scaling of the bending strength or flexural strength of the model ice. Recent research on the mechanical behavior of model ice shows a significantly higher compliance in downward bending than targeted when following the applied scaling laws. This can lead to scale effects in the resistance force also when testing ice breaking ships. The too compliant ice facilitates an additional ride-up of the ship onto the ice and the vertical motions manifest as additional resistance contribution. The low compliance of model ice also imposes uncertainties on wave-ice interaction tests, which gain increasing significance due to the climatic changes in Polar regions. The modeling of ice break-up due to waves, with the current standard model ice, requires much steeper waves than in full scale as the ice surface needs to experience a much higher deflection to reach the critical failure stress. A similar issue arises for vertical structures exposed to drifting ice. In full-scale a pile-up of ice around the structure is observed and in the contact area so called high-pressure zones may form. Such effects cannot be modeled with classic model ice as it easily bends downwards and produces a failure pattern and failure process very different from full-scale as well as high-pressure zones do not form which is due to the string property gradient in model ice. The mentioned three scenarios are considered being highly relevant in marine research and for the marine industry and therefore this paper introduces two new model ice types with which those scenarios can be modeled. The ‘model ice of virtual equivalent thickness’ uses a different modeling approach to reach a scaled stiffness for improved modeling of waves in ice and ships’ resistance in thicker ice. The ‘wave model ice’ is modeled by using waves in the formation process and can resemble high-pressure-zones acting on a vertical structure. Both methods are considered as an extension to the existing standard model ice for dedicated scenarios by scaling or putting emphasis on different ice properties by altering the production process. The presented approach also emphasizes case-based-scaling, which means that the scaling or the model ice type needs is defined by the modeled scenario as the standard model ice is obviously not fully capable to reflect all properties of sea ice in scale.

Flow induced vibration (FIV) from high velocity multiphase flow is a common source of vibration concern in process piping, potentially leading to fatigue failures and hydrocarbon leaks. FIV screening methods tend to be conservative for multiphase flows and are typically only validated for simple single bends at low pressure. FE can predict the response of a system if a sensible forcing function is provided. CFD can be used to predict realistic forcing functions in complex combinations of bends and tees, typically seen in process piping systems. FIV studies were performed on a topside production system operated by Equinor, carrying multiphase flow at high pressure (∼69 bara) conditions, where significant vibration was measured. The study assessed different vibration simulation methodologies, combining FE analysis with forcing functions based on both correlations and CFD simulations. The aim was to gain a better understanding of the accuracy and limitations of calculation methods typically used to assess fatigue. CFD simulations predicted similar force magnitudes but higher frequency forcing at 69 bara compared to equivalent simulations at atmospheric pressure (at the same liquid and gas superficial velocities). The forcing function correlations used do not predict higher frequency forcing at high pressure, which has a significant impact on the predicted vibration. Care is required when undertaking this type of analysis. It is important to have an accurate FE model of the as-built pipework and supports as well as a forcing function which accurately represents the fluid forces on the bends. For the case simulated here the magnitude and peak frequency of the forcing function had a significant influence on the response of the structure. Forcing functions based on correlated data from tests at low pressure should be used carefully for high pressure systems. In addition, the inclusion of phasing of the forces at each bend can influence the structural response, and simulations performed in the frequency domain do not consider this. A combination of CFD and FE modelling offers a potentially powerful tool for assessing and diagnosing multiphase FIV problems in hydrocarbon production piping systems.

The South China Sea has rich natural gas source with typical high-pressure high-temperature (HPHT) and the extremely narrow drilling window, which leads to frequent influx, even borehole abandonment. However, horizontal gas wells have been placed in the area to develop the gas reservoir, which presents greater well control challenges. Therefore, the influx risk evaluation is quite necessary to guide the well control design. Firstly, the influx mechanism is analyzed based on gas intrusion to provide a theoretical basis for well control design. It is found that influx usually occurs when drilling the high-temperature stratums and target layers. Secondly, the relationship between horizontal open-hole length and influx volume is calculated under different reservoir permeability, reservoir thickness, negative bottom hole pressure and horizontal open-hole section length. Thirdly, the characteristics of gas-liquid two-phase flow are described. Fourthly, the inflow risk evaluation and well control strategies of the target horizontal gas wells are proposed, and the influx risk evaluation envelope was established. The influx risk evaluation and well control strategies have been successfully applied to the DF gas field featuring offshore HPHT. Horizontal gas wells were drilled in the micro pressure window without accidents and the well cost was significantly reduced.

Understanding the interaction between the drilling fluid and the natural gas from a gas kick may be of great importance when predicting how a well control incident evolves during drilling operations. This is especially true for oil based mud, which has the ability to dissolve large quantities of gas under high pressure, thus potentially hide any volumetric impact of a gas kick. When the pressure of the dissolved gas decreases below the bubble pressure, free gas will start to emerge. Dangerous situations can occur if the bubble point pressure is low and located close to the surface. This may result in a rapid volumetric expansion of the free gas, as it emerges from solution, thus little to no time to react and initiate proper well control procedures. Most conventional well control simulators that takes gas solubility into consideration assumes an instantaneous vaporization of gas as the vapour-liquid phase equilibria changes. However, this assumption might not always be realistic. It may take some time before a new equilibrium is reached when the conditions are changed. This will thus affecting the rate of gas liberation from the liquid. To better understand this complex issue, an analytical expression for the transition rate of dissolved gas to free gas in a supersaturated liquid has been derived for low pressure systems. The analytical model is strongly dependent on the solubility coefficient, K h , and the transition rate factor, γ, and follows an exponential curve. In this expression, K h is a measure of how much the liquid is supersaturated at any given time and controls how much gas that will be liberated. γ determines how fast the system will reach a new equilibrium, i.e. how fast the gas will be liberated based on the size of the supersaturation. Both K h and γ are thought to be values given for a specific gas-liquid combination. In order to verify the analytical expression, experimental testing has been conducted. The experiment is carried out by pressurizing a tank partly filled with the base oil Exxsol D60 by feeding it with methane gas. Some of the gas will dissolve into the liquid. The rest will flow to the top as free gas and pressurize the tank. By quickly removing some of the free gas, thus depressurize the tank, the liquid will instantaneously become supersaturated, hence triggering liberation of free gas from the solution until a new equilibrium is established. By measuring the tank pressure throughout the degassing phase, values for K h and γ can be estimated and compared to the analytical model.

High pressure gas pipeline must maintain structural integrity during the design life. To do this, periodic pipeline inspections are carried out, and fitness-for-service assessments are performed on defects found by inspection. Defects that do not meet the evaluation criteria should be repaired and replaced to ensure the integrity of the pipeline structure at the same level as before the defect. High pressure gas pipeline repair method is applied to repair of composite reinforced sleeve and repair of steel sleeve. Although there have been many studies on the short-term structural integrity evaluation of rupture pressure in these repair methods, there is insufficient research to verify whether the long-term operation of the repair pipeline maintains the long-term structural integrity of the repaired pipe. In this study, an optimum process to improve structural integrity was established by investigating effect of the process variables on fatigue lifetime of steel-sleeve repair welds in buried gas pipeline. Residual stresses in the repair welds were derived through sequentially-coupled temperature-stress analysis using ABAQUS, which is a commercial finite element analysis program. In addition, variations of operating stresses were derived by finite element linear elastic stress analysis. Fatigue lifetimes of the steel-sleeve repair welds were evaluated by substituting the derived weld residual stresses and operating stress variations into the structural stress/fracture mechanics approach as input. Appling this method confirms long-term integrity over 200 years in terms of fatigue the abstract here in italics.

The Direct Current Potential Drop (DCPD) method is a common method used to detect the initiation of cracks, measure crack growth rates and monitor crack propagation. The method records total measurement of crack propagation, and can be used without visual accessibility, being suitable for special environments like high temperature, high pressure and sour service. Due to the discontinuity represented by the presence of a crack, when electric current flows through the component the crack size can be measured indirectly by the change of the electrical field. The potential difference can be related to crack size through experimental, analytical or numerical calibration curves. Analytical solutions are only limited to a small number of simpler geometries and homogeneous material. For clad and lined pipe, the clad/liner is stainless steel or nickel base alloys but the base pipe is carbon steel. The conductivities of the different materials are different. For lined pipe a small gap exists between liner and base pipe, this may change the electrical field around the root of girth weld. In this paper, finite element analyses are performed to generate the numerical calibration curves for the fatigue crack growth rate testing in sour service environment for clad and lined pipe girth welds. The method developed and described in this paper measures the fatigue crack growth rate for the crack located at the weld root which is in direct contact with the operating environment.

The explosion in the closed cabin will cause a sharp rise in cabin gas pressure, which will cause serious damage to the cabin structure. The quasi-stationary pressure, due to its long duration and large impulse, plays a major role in the destruction of the structural strength of the entire cabin. The venting holes on the transverse bulkheads can effectively guide the release of energy to other locations, reducing the damage to the cabin. In this paper, the quasi-stationary pressure generated during cabin explosion with venting is studied. According to the conservation of mass and energy, the cabin explosion model with venting is transformed into an equivalent high pressure gas release model to simulate the initial instantaneous state of cabin explosion, and it is verified by finite element calculation that the two models are equivalent in predicting quasi-stationary pressure. The entire gas flow process during the exploding with venting holes is divided into two parts: the gas flow in the cabin to the venting hole and the venting hole to the atmosphere. An approximate analytical method for predicting quasi-stationary pressure generated during cabin explosion with venting is improved by using Bernoulli equation and isentropic compression formula of ideal gas, and the results of the improved calculation method are compared with the results obtained by the numerical simulation method to verify its validity.

The exploration of oil & gas fields towards more demanding environments require the continuous development of line pipe steels capable to withstand severe working conditions (high pressure, high temperature, sour environment, large deformations) maintaining good weldability in terms of hardness control in the Heat Affected Zone (HAZ). Therefore, the response to welding thermal cycles needs to be taken into account since the first steps of the product development. This paper describes a methodology to ascertain the weldability of new line pipe steels. A matrix of welding trials, based on different welding technologies, was designed; the manufactured welds were assessed in terms of hardness and microstructure using standard and non-standard approach. Gas Tungsten Arc Welding (GTAW) cold wire technique with anthropomorphic robot was selected as principal process, being extremely robust, accurate and repeatable and able to reproduce with good accuracy the thermal field of different arc welding operations. Furthermore, GTAW process permits to manage separately the so called “Arc Energy” (Volt*Ampere) and wire feeding: this additional degree of freedom gives the possibility to produce different combinations of Heat Inputs and Diluting Ratios. Single and multi-pass bead on plates (WT∼40mm) with no pre-heating were used to promote high restrained configurations and high residual stresses to reproduce the worst welding condition. Furthermore bead on plate have been performed by Nd:YAG laser to generate fastest cooling rates and narrowest welding pools. The investigation activity was performed according to the API RP 2Z for what concerns the characterization of the main Heat Affected Zone both for single and multi-pass. For the individuation and investigation of the HAZ sub-zones a thermal model has been selected, validated by dedicated instrumented welding activity and used to predict the thermal cycle in selected points/zones of the HAZ (e.g. CGHAZ, FGHAZ...). In depth metallographic/hardness analysis was performed on the welded samples using non-standard methods: low, medium and high magnification optical microscope analysis to generate a complete morphological map, suitable hardness paths with low and standard loads along the main direction of heat propagation in the bead and “tint etching” to better individuate the phase fractions of the different sub-zones of the HAZ. Finally, proprietary and commercial predictive tools, using different input parameters (e.g. heat input, cooling rate, composition...) were used to calculate hardness and phase fractions under the experimental operative conditions. Results were compared to those obtained by the experimental activity.

The flexible pipes are widely used in the oil and gas industry to transport petroleum products. The pipe might burst fails when a large internal fluid pressure acts on the pipe, and the consequences are disastrous. In order to ensure the security and reliability of flexible pipes in the application, the mechanical responses of the pipe subjected to high pressure loads should be carefully estimated. The main purpose of this paper is to investigate the burst pressure of the pipe. Based on the principle of virtual work, a theoretical model for stress and deformations of the pipe is established, which takes the material plasticity into consideration. In addition, a finite element model is developed by ABAQUS to verify the feasibility of the theoretical model. According to the verified model, it is efficient to predict the burst pressure and design its cross-section economically with its serving conditions.

As the exploitation of oil and gas gradually enters the deep sea, the low-temperature and high-pressure deep-sea environment poses a huge challenge to the flow protection of pipelines (2014a). In this paper, the phase change material sandwich pipeline which uses phase change heat storage and exothermic to maintain the pipeline temperature is taken as the research object, the heat transfer characteristics of the deep-water phase change material sandwich pipe are studied through the combination of theoretical analysis and numerical simulation (2014b). The main contents include: Firstly, through the establishment of two-dimensional and three-dimensional pipe models, analyzed the temperature distribution along the pipeline and the radial temperature distribution of the pipeline under steady oil flow conditions. Secondly, by using transient heat transfer, the effects of phase change material parameters, the proportion of phase change material in the insulation layer, and the difference in the ratio of phase change materials in the insulation layer on the insulation performance are analyzed to obtain the best results. Insulation material and optimal insulation layer layout; finally, the thermal storage and the phase change conditions of the phase-change material sandwich pipe is studied under the re-starting condition. The results show that the effective holding time of the phase change material insulation layer is close to 1.4 times that the non-phase change material insulation layer, and the melting point size has little effect on the insulation material. The closer the phase change material is to the inner tube, the better the insulation effect. This study provide guidance for the design and utilization of phase change material sandwich pipe.

Computational Fluid Dynamics (CFD) simulations are used to predict the flow-induced forcing in high-pressure multiphase pipe flow. Furthermore, empirical correlations from the literature is compared and validated against computational and experimental results. Based on the CFD results and in conjunction with the reference 6” (internal diameter (ID)) data, new scaling rules are proposed.

Distributed buoyancy method is one of the buckle initiation techniques used to trigger controlled lateral buckling at planned locations for subsea pipelines operating under high temperature and high pressure (HT/HP) conditions. Deviations from a straight profile for pipelines may be introduced by the pipe-laying vessel’s sway motion during the installation process. In this study, analytical solutions of lateral buckling are deduced for imperfect unburied subsea pipelines with a distributed buoyancy section. The effect of initial imperfections on buckled configurations and typical post-buckling behaviours is illustrated and analysed. The results show that, compared to the case without initial imperfection, lateral displacement amplitude becomes larger when initial imperfection exists. Maximum compressive stress increases when wavelength of initial imperfection is smaller than buckled length of pipeline. However, maximum compressive stress decreases when wavelength of initial imperfection is larger than buckled length of pipeline. So it’s better to introduce longer wavelength of initial imperfection.

High pressure high temperature offshore pipelines are generally buried for protection. For buried pipelines, upheaval buckling can be triggered in the presence of vertical imperfections when the pipeline compressive state is increased. One of the main uncertainties in the design calculation is the soil resistance to upward and downward movement and the displacement at which the peak resistance is mobilised. For clays the soil response will usually be undrained, certainly for most loading events, however it may also be necessary to consider the drained response (particularly if there is any long term applied uplift). In addition, local flow-round failure mechanism may occur, generally for deeply buried pipelines. If local failure dominates the design, it may not be possible to bury the pipeline. This could have significant cost implications. An experimental programme was carried out to determine the uplift resistance of buried pipelines in soft clay soils. The results of scale model testing and computational analysis (finite element limit analysis) showed that the local behaviour was not applicable. The implications of these results are illustrated in a case study upheaval buckling (UHB) analysis. The overall result was a significant saving on rockdump quantities. The implications for the case study are presented in this paper alongside a description of other backfill requirements and practical considerations for a UHB design.

This paper experimentally investigates the feasibility and efficiency of using Carbon Fiber Reinforced Polymer (CFRP) buckle arrestors in controlling the buckle propagation failure of subsea pipelines. Hyperbaric chamber tests are conducted on 1.6m Steel pipe with D/t = 28 and using CFRP buckle arrestors with different thickness, fiber orientation and spacing. Using an external pressure gauge and a high-pressure camera inserted inside the hyperbaric chamber, the pressure magnitude, rate and shape of collapse and its propagation in the vicinity of the arrestors are measured. The dynamics of buckle propagation and efficiency of different arrestor configurations are reported. It is observed that in the vicinity of the CFRP arrestors wrapped in the hoop direction, the well-known dog-bone buckle shape changes into a U-shape and the pressure level upsurges significantly. The optimum results were obtained with CFRP as thick as the pipeline wall-thickness and wrapped in the hoop direction of the pipeline. The results show that at similar arrestor efficiency, the CFRP arrestors can be much thinner than the existing steel slip-on arrestors. Also, the spacing between the CFRP arrestor can be larger than that of the steel slip-on arrestor.

This paper presents two case studies of the seismic analysis of high pressure riser and conductor systems used on shallow water fixed platforms (approximately 120m water depth) offshore Newfoundland and Labrador, Canada. The case studies presented consider the Hebron and White Rose extension Husky gravity-based concrete platforms. A methodology is presented to assess the dynamic and resonant response of each conductor and riser system to seismic loading using a fully integrated conductor and platform interaction model. Seismic loading is an application of an earthquake-generated agitation to a structure. This occurs at contact surfaces either with the ground, or with adjacent structures, or with gravity waves. Nonlinear time history analyses of the riser system subjected to various ground motion records are performed to simulate the seismic load. Design considerations that drive the HP riser design are discussed. The paper addresses the intricacies of the gravity base concrete platform-riser system interaction, initial configuration and dynamic seismic response. The riser and conductor system response is used to determine HP riser connector and centralization requirements. The learnings taken from the detailed modeling method are presented along with the advantages of this methodology.

As the industry plans to move forward with the development of high pressure and high temperature (HP/HT) fields, challenges exist for the design of complaint risers in deepwater applications. The conventional wet tree application risers such as Steel Catenary Risers (SCRs) have proven to be mature technologies in the deepwater applications around the world. HP/HT application leads to many challenges in deepwater risers. This paper investigates ways to overcome the design challenges of deepwater SCRs using a multi-pronged approach. The paper first addresses the challenge in riser pipe wall thickness. The HP/HT applications require higher pipe wall thicknesses mainly governed by the burst pressure design requirements. The pipe wall thicknesses required for the HP/HT applications will result in very high installation loads, reeling issues with low D/t, fabrication (welding) challenges, high payloads to the host vessel, etc. Any optimization to the wall thickness design in terms of using higher grade material, advancements in welding technology and advantages to be gained in the use of design codes can potentially help in overcoming of these challenges. The pipe sizes used in the HP/HT applications can pose significant challenges to the touchdown zone (TDZ) of standard steel catenary riser configurations, in terms of experiencing large TDZ compressions and having fatigue life concerns. Use of different SCR problem-solving approaches — TDZ clump weights, Lazy Wave Steel Riser (SLWR) and weight optimized risers will be reviewed in this paper. Vessel motion characteristics can significantly affect the riser performance. Vessels with improved motions, particularly from the riser response viewpoint, can play a significant role in the selection of optimum riser configurations. This has to be achieved in the early stages of the project. Some of the work done recently in development of the optimized vessel performance particularly in the case of semi-submersibles and their implications on the riser design are studied in this paper. Design of the risers in HP/HT fields in deepwater applications presents significant challenges and requires a multi-dimensional problem solving approach. An example is provided in this paper for the investigation. A multi-pronged approach has to be adopted for the successful design of riser system for HP/HT deepwater applications.