During the last decade, inflow control device (ICD) technology has rapidly developed and widely been used in horizontal wells due to its effectiveness in flux equalization and mitigation of unwanted fluid breakthrough. An ICD completion achieves flux equalization and manages water breakthrough by introducing an extra pressure drop in the ICD and redistributing the drawdown across the sandface between high and low permeable intervals of a horizontal well. This additional pressure loss in the ICD completion will cause reduction of effective productivity of the well, in other words it will require lower flowing bottom-hole pressure for a well with ICD completion to produce the same liquid rate compared to a well with a barefoot completion. The higher the pressure drop across the ICD completion, the better will be the equalization effect and water mitigation. Subsequently, the reservoir pressure has to be used wisely during field development as expensive pressure maintenance programs are utilized in many fields as part of the field development plans. This study tries to answer an important question: What should the optimum pressure regulation in an ICD completion be to realize the benefits of ICD without excessive reduction of well productivity? The effect of ICD regulation on flux equalization and well productivity reduction for various cases of well productivity index (PI) and permeability variation were studied through numerous static near wellbore simulation runs. Dynamic reservoir simulation was conducted to verify the results from the static simulation and dependence of the degree of flux equalization along the horizontal section on water breakthrough deferment and the oil recovery factor. An ICD design workflow is presented, which can be used to select an optimum ICD design, which maximizes the benefits of ICD with the least reduction in well productivity. A trade-off chart between well productivity and the degree of influx equalization has been built, which helps to determine the optimum pressure drop across an ICD completion in the presence of various levels of permeability variation along the wellbore. This approach can provide quick and simple calculation for the required ICD strength or number of ICD joints along the wellbore to maximize recovery of hydrocarbons. A real field case is used to illustrate the effectiveness of this workflow for optimum ICD design.
Inflow Control Device (ICD) are deployed as a part of downhole completion across the horizontal section in consolidated or unconsolidated formations to overcome challenges posed by long horizontal drains like heel to toe effect and formation heterogeneities. The main objective of ICD completion is to delay water or gas breakthrough by enabling equalization of flux along the wellbore and promote oil by chocking back water in case of water breakthrough. Recently, for the first time in sandstone fields, a new ICD generation combining three advanced features in one was successfully installed enabling simple and safe deployment of an optimum completion design for a long horizontal well. The new ICD is a combination of new hybrid ICD design, multi-tasking valve (MTV) and premium sand screen. The new ICD generation incorporates a hybrid design in which the fluid flows in a labyrinth path to achieve optimum pressure drop. The new design makes the ICD highly density dependent and insensitive to viscosity while maintaining a larger flow area which makes is less prone to plugging and erosion compared to conventional ICDs. MTV, a delayed opening valves incorporated into the ICD allowing them to act as a pressure containing liner component. This enables a true flow through full circulation from the bottom of the completion assembly eliminating the need of inner string during deployment. Having MTV feature in the ICD has made the deployment not only simple and safe but also saved considerable amount of rig operation time compared to conventional ICD screens by eliminating the need for inner string. Risk of low productivity of well due to screen plugging by mud solids in OBM was also reduced by achieving a higher annular velocity during deployment and pumping wellbore clean-up treatment fluid. This paper will discuss the benefits of the new generation ICD on completion operation based on experience from the first deployment and highlight the operational cost saving by reducing the rig time. In addition, the impact of the new hybrid design on the well production performance will be discussed highlighting the post drilling benefits and how it would prolong the well life.
Conventional Off-bottom Cemented (OBC) application with Inflow Control Device (ICD) presents several challenges for well completion operations. Operational and HSE risks, complexity of deployment with several hydraulic activated tools, excessive operational time, and associated costs being some of them. This paper presents first successful deployment of a new generation integrated off-bottom cemented closed system ICD completion installed in a challenging offshore sandstone environment in Middle East with proper engineering, HSE risks were reduced while saving considerable rig time compared to the conventional system. To address the challenges posed by OBC with ICDs application a new system consisting of full-bore closed system ICD screens, full-bore mechanical open hole packers and a fit for purpose dual opening pressure activated cementing valve (DPACV) were developed. The system allows for installation of ICD screens and zonal isolation open hole (OH) packers with off-bottom cemented completion in one-trip with no dedicated work string run to set OH packers. Furthermore, the full-bore access allows drill-out of cement/plug and drifting lower completion in one clean-out run with 3.875" OD/ gauge bit, which was previously performed in two separate runs due to size limitations. The system brings significant cost-savings, reduced rig time, and expedited well delivery. This system also allows for reduced wellbore exposure time, more efficient displacement rates/volumes for dissolving filter cake, with better production ID and easier future well interventions. The new system was deployed in a critical re-entry horizontal well in a sandstone reservoir. The objective of the completion was to isolate non-reservoir section and an active gas cap below the kick-off window with off-bottom cemented liner and completing the reservoir section with ICD sand screens and open hole packers. The challenge in deployment was due to unstable hole conditions, active shale & possible wash outs sections. The performance of the new system was evaluated by comparing it to a conventional system installed in the same field. The off-bottom cemented ICD system was successfully deployed to target depth in challenging open hole conditions. The activation of all tools and the off-bottom cement job went as per plan. Performance comparison showed that the new system was completed 42% more efficiently than the standard conventional completion deployment time, saving significant rig time and cost. The most time saved was achieved by eliminating tripping in and out with wash pipe for setting the OH packers. Drill out of cement/plug and drifting of the lower completion was done in a single cleanout trip compared to two separate trips in a conventional system. Post completion, production and noise logging confirmed positive isolation of the gas cap from the reservoir section, confirming all packers sealing integrity, and the production log confirmed inflow from all ICD compartments as per design. This paper presents the development and installation of a first of its kind integrated OBC with ICD screen system, which brings significant cost-savings and reduced rig time.
Field development of a mature, highly fractured carbonate field presents several challenges. Most of the horizontal wells drilled in such fractured reservoirs suffer from early gas or water breakthrough because conductive fractures dominate the influx from the reservoir and cause an unbalanced flux profile along the wellbore. Premature gas or water breakthrough can result in poor sweep efficiency and reduced oil recovery for the well. To address the aformentioned challenges, passive inflow control devices (ICDs) can be used to equalize influx from the reservoir to the wellbore, thereby delaying gas or water breakthrough. However, during the life of the well, as water or gas breakthrough occurs, a passive ICD can be less effective in preventing water or gas production. This can effect well productivity and reduce the production life of the well, especially for a naturally flowing well. This paper describes how adjustable ICD technology with a sliding sleeve can be used as an effective reservoir management tool in mitigating challenges faced in a naturally fractured Middle Eastern carbonate field. Various examples from the subject field are presented to describe production challenges faced by barefoot and passive ICD-completed horizontal wells. The field cases suggest the need for adjustable ICD with sliding sleeve technology which provides a zonal shut-off option in case of water or gas breakthrough. A detailed workflow for usage of adjustable ICDs is described, and which includes well candidate selection, well monitoring and pre and post shifting well performance evaluation to determine which ICD unit must be shifted to a closed or open position. A dynamic simulation using a single-well model was also conducted to establish the benefits of a sliding sleeve on well production performance. An adjustable ICD with a sliding sleeve was chosen as the preferred completion technology over the passive ICD for horizontal wells for the subject field with a naturally fractured carbonate reservoir. A sliding sleeve integrated in an ICD is a simple and cost-effective tool for zonal water or gas shut off compared to conventional intervention technology available for horizontal wells. Sliding sleeves maximize the value of ICD technology by adding an adjustability feature to ICD to overcome the challenges faced by unexpected changes in well behavior and premature water or gas breakthrough. Dynamic simulation results also confirm the sliding sleeves can prolong the life of the well by reducing high water and free gas production, thereby increasing cumulative oil production.
One of the main challenges that today’s drilling operation faces is uncertainty in formation pressures. Excessive overbalance between the Equivalent Circulating Density (ECD) and formation pressure causes unnecessary, often detrimental formation breakdown, while underbalance drilling increases the risk of drilling kicks which can lead to catastrophic blowouts at the worst case scenario. Due to the uncertainty in formation pressures, managing the ECD becomes quite challenging and difficult. The ECD presents a significant drilling parameter particularly in wells that have a narrow window between the fracture gradient and pore-pressure gradient. Therefore, as early as possible knowledge of pore pressures, is highly sought after by the operating company. Formation pressure while drilling (FPWD) technology has proved over the past few years to provide accurate formation pressures during drilling. Apart from the use of formation pressures to calculate fluid gradients, mobilities and identify tight zones, it has also found its usefulness in ECD management. This paper presents a case study from an onshore horizontal well in the Middle East, which discusses the successful application of FPWD in ECD management. Due to the lack of reservoir formation pressure data, a heavier mud than necessary was used to drill the reservoir section to avoid risk of formation fluid influx. However, accurate measurements of pore pressures in real time recorded from a FPWD tool indicated lower pore pressures than expected. Consequently, based on that real time data, decision was made to significantly reduce the ECD, which resulted in improved hole cleaning, performance, increased rate of penetration, among other benefits.
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