Challenges from Well Shut-in Amid the Oil Downturn: Long Term Impacts on Near Wellbore Skin Buildup and Sand Control

2021 ◽  
Author(s):  
Mohammad Soroush ◽  
Mahdi Mahmoudi ◽  
Morteza Roostaei ◽  
Hossein Izadi ◽  
Seyed Abolhassan Hosseini ◽  
...  
Keyword(s):  
Hot Spot ◽  
Oil Production ◽  
Well Performance ◽  
Well Completion ◽  
Flow Control Devices ◽  
Sand Control ◽  
Control Devices ◽  
Inflow Problem ◽  
The Impact

Abstract In wake of the biggest oil crash in history triggered by the COVID-19 pandemic; Western Canada in- situ production is under tremendous price pressure. Therefore, the operators may consider shut in the wells. Current investigation offers an insight into the effect of near-wellbore skin buildup because of such shut-in. A series of simulation studies was performed to quantitatively address the impact of well shut-in on the long-term performance of well, in particular on key performance indicators of the well including cumulative steam to oil ratio and cumulative oil production. The long-term shut-in contributes to three main modes of plugging: (1) near-wellbore pore plugging by clays and fines, (2) scaling, and (3) chemical consolidation induced by corrosion. A series of carefully designed simulations was also utilized to understand the potential of skin buildup in the near-wellbore region and within different sand control devices. The simulation results showed a higher sensitivity of well performance to shut-in for the wells in the initial stage of SAGD production. If the well is shut in during the first years, the total reduction in cumulative oil production is much higher compared to a well which is shut-in during late SAGD production life. As the induced skin due to shut-in increases, the ultimate cumulative oil production drops whose magnitude depends on well completion designs. The highest effect on the cumulative oil production is in the case of completion designs with flow control devices (liner deployed and tubing deployed completions). Therefore, wellbore hydraulics and completion design play key roles in the maintenance of uniform inflow profile, and the skin buildup due to shut-in poses a high risk of inflow problem and increases the risk of hot-spot development and steam breakthrough. This investigation offers a new understanding concerning the effect of shut-in and wellbore skin buildup on SAGD operation. It helps production and completion engineers to better understand and select candidate wells for shut-in and subsequently to minimize the skin buildup in wells.

Data-Driven Well Pad Development Performance Review: Focus on the Role of Liner Design on Well Performance

2021 ◽  
Author(s):  
Hossein Izadi ◽  
Morteza Roostaei ◽  
Mahdi Mahmoudi ◽  
Seyed Abolhassan Hosseini ◽  
Mohammad Soroush ◽  
...  
Keyword(s):  
Oil Production ◽  
Relative Performance ◽  
Data Driven ◽  
Thickness Variation ◽  
Well Performance ◽  
Drainage Volume ◽  
Well Completion ◽  
Flow Control Devices ◽  
Using Data

Abstract Steam Assisted Gravity Drainage (SAGD) is the dominant in-situ method for oil production in Western Canada. The current study analyzed the relative performance of various well-completion practices using data from 4,000 well pairs that were drilled over a decade. The data analysis provided a unique opportunity to find best operating practices. The scope of this paper is to review the performance of major thermal projects in Canada and investigating the effect of liner design and Flow Control Devices (FCDs) on well pair performance and development. Cumulative oil production and cumulative steam oil ratio (cSOR) were used as the key metrics in comparing the well performance in a SAGD operation. However, to compare different pads and different projects, it was critical to normalize the data with geological variation, well length, well spacing, and with consideration to the well failure rate, remedial completion and re-drills. In this paper we review seven thermal projects of four key operators with almost 3,500 wells and 1,200 well pairs in operation as early as 1996. All geoscience, and production/injection data have been extracted from public databases and utilized to develop a data-driven model. The reservoir thickness variation for each well was determined using available geoscience data, and through the development of a geological model based on the available core data and well logs. The model was used to define the drainage volume for each well pair, which in turn was used to assign a geological ranking to the well. The cumulative oil production and cSOR were then normalized with the geological ranking and the size of the net drainage volume. The number of well pairs in each pad and the cumulative pad production were normalized against the number of days in production and their relative decline, which allowed for comparison between pads within the same project, as well as pads from other projects. The cumulative production of the active pads in each project was used to compare the relative performance of different projects. Also, we separated the projects and wells based on their use of FCDs in the producer and injector to compare the relative performance of each technology in the field. This paper is the initial phase of the study on the role of completion design on relative well and well pad performance. The results will help completion and production engineers to better understand the well pair and pad relative performance and how to normalize the oil production data against geological variation to compare performance.

Unlocking By-Passed Oil with Autonomous Inflow Control Devices Through an Integrated Approach

2021 ◽  
Author(s):  
Pawan Agrawal ◽  
Sharifa Yousif ◽  
Ahmed Shokry ◽  
Talha Saqib ◽  
Osama Keshtta ◽  
...  
Keyword(s):  
Continuous Production ◽  
Oil Production ◽  
Gas Production ◽  
Oil Field ◽  
Production Performance ◽  
Fluid Distribution ◽  
Flow Profile ◽  
Horizontal Drain ◽  
Control Devices

Abstract In a giant offshore UAE carbonate oil field, challenges related to advanced maturity, presence of a huge gas-cap and reservoir heterogeneities have impacted production performance. More than 30% of oil producers are closed due to gas front advance and this percentage is increasing with time. The viability of future developments is highly impacted by lower completion design and ways to limit gas breakthrough. Autonomous inflow-control devices (AICD's) are seen as a viable lower completion method to mitigate gas production while allowing oil production, but their effect on pressure drawdown must be carefully accounted for, in a context of particularly high export pressure. A first AICD completion was tested in 2020, after a careful selection amongst high-GOR wells and a diagnosis of underlying gas production mechanisms. The selected pilot is an open-hole horizontal drain closed due to high GOR. Its production profile was investigated through a baseline production log. Several AICD designs were simulated using a nodal analysis model to account for the export pressure. Reservoir simulation was used to evaluate the long-term performance of short-listed scenarios. The integrated process involved all disciplines, from geology, reservoir engineering, petrophysics, to petroleum and completion engineering. In the finally selected design, only the high-permeability heel part of the horizontal drain was covered by AICDs, whereas the rest was completed with pre-perforated liner intervals, separated with swell packers. It was considered that a balance between gas isolation and pressure draw-down reduction had to be found to ensure production viability for such pilot evaluation. Subsequent to the re-completion, the well could be produced at low GOR, and a second production log confirmed the effectiveness of AICDs in isolating free gas production, while enhancing healthy oil production from the deeper part of the drain. Continuous production monitoring, and other flow profile surveys, will complete the evaluation of AICD effectiveness and its adaptability to evolving pressure and fluid distribution within the reservoir. Several lessons will be learnt from this first AICD pilot, particularly related to the criticality of fully integrated subsurface understanding, evaluation, and completion design studies. The use of AICD technology appears promising for retrofit solutions in high-GOR inactive strings, prolonging well life and increasing reserves. Regarding newly drilled wells, dedicated efforts are underway to associate this technology with enhanced reservoir evaluation methods, allowing to directly design the lower completion based on diagnosed reservoir heterogeneities. Reduced export pressure and artificial lift will feature in future field development phases, and offer the flexibility to extend the use of AICD's. The current technology evaluation phases are however crucial in the definition of such technology deployments and the confirmation of their long-term viability.

Liner Deployed Flow Control Devices in SAGD Infill Producers

2021 ◽  
Author(s):  
Michael Hardcastle ◽  
Ryan Holmes ◽  
Frank Abbott ◽  
Jesse Stevenson ◽  
Aubrey Tuttle
Keyword(s):  
Flow Control ◽  
Oil And Gas ◽  
Distributed Temperature Sensing ◽  
Steam Assisted Gravity Drainage ◽  
Well Production ◽  
Flow Control Devices ◽  
Control Devices ◽  
The Impact ◽  
Mobility Variable

Abstract Connacher Oil and Gas has deployed Flow Control Devices (FCDs)on an infill well liner as part of a Steam Assisted Gravity Drainage (SAGD) exploitation strategy. Infill wells are horizontal wells drilled in between offsetting SAGD well pairs in order to access bypassed pay and accelerate recovery. These wells can have huge variability in productivity, based on several factors: variable initial temperature due to variable steam chamber development and initial mobility variable injectivity from day one limiting steam circulation and stimulation significant hot spots during production that limit drawdown of the well and oil productivity FCDs have shown great value in several SAGD schemes and are becoming common throughout SAGD applications to manage similar challenges in SAGD pairs, but their application in infill wells is less prevalent and presents a novel challenge to design and evaluate performance. This case study will examine the theory, operation, and early field results of this field trial. Density-based FCDs designed for thermal operations were selected to minimize the impact of viscous fluids commonly encountered early in cold infill well production. The design also limited steam outflow during the stimulation phase, where steam is injected in order to initiate production of the well. Distributed Temperature Sensing (DTS) data, pressures and rates are utilized to analyze the impact of the FCDs towards conformance of the well in the early life. The value of FCDs has led to further piloting of this technology in a second group of nine infill wells, where further value is to be extracted using slimmer wellbores.

Maximizing Asset Value & Field Recovery with Advanced Completion Solutions – A Digital Twin Field Case Study with Multilateral, Intelligent Completion, and AICD Completion Technologies

2021 ◽  
Author(s):  
Noman Shahreyar ◽  
Ben Butler ◽  
Georgina Corona
Keyword(s):  
Reservoir Simulation ◽  
Simulation Software ◽  
Well Performance ◽  
Reservoir Model ◽  
Additional Information ◽  
Well Completion ◽  
Asset Value ◽  
Reservoir Conditions ◽  
Control Devices

Abstract The drilling and completion of multilateral wells continues to expand and advance within the oil industry after three decades of accelerating adoption. The performance of these wells can be increased when integrated with advanced well completion techniques. The addition of intelligent completions (IC) and inflow control devices (ICD/AICD) enhances well performance and improves field recovery. This paper discusses a reservoir simulation case study that evaluates the productive impact these technologies provide when combined with multilateral technology (MLT), and the mechanism by which they achieve it. A reservoir model is devised and simulates under dynamic reservoir conditions the field production of dual lateral and single bore horizontal wells. The simulation is conducted for three separate scenarios where AICD and IC are incrementally implemented. The results are compared across the scenarios and their value quantified. The mechanisms by which estimated ultimate recovery (EUR) is increased will be discussed, including the increase of reservoir contact, drawdown distribution optimization, and the control and delay of water production. The study will provide an overview on the theory behind the technologies. It will also review the workflow used to conduct the study, utilizing a combination of steady state nodal analysis software and dynamic reservoir simulation software. Additional information about the reservoir model, initial and boundary conditions are detailed, to provide insight into reservoir simulation methodology.

Development of Tight Upper Cretaceous Reservoir in Offshore Black Sea Adds Life to a Mature Asset

2021 ◽  
Author(s):  
I. Mitrea ◽  
R. Cataraiani ◽  
M. Banu ◽  
S. Shirzadi ◽  
W. Renkema ◽  
...  
Keyword(s):  
Black Sea ◽  
Upper Cretaceous ◽  
Rock Physics ◽  
Oil Production ◽  
Economic Life ◽  
Production Performance ◽  
Single Fracture ◽  
Well Performance ◽  
Acoustic Image ◽  
The Impact

Abstract This Upper Cretaceous reservoir, a tight reservoir dominated by silt, marl, argillaceous limestone and conglomerates in Black Sea Histria block, is the dominant of three oil-producing reservoirs in Histria Block. The other two, Albian and Eocene, are depleted, and not the focus of field re-development. This paper addresses the challenges and opportunities that were faced during the re-development process in this reservoir such as depletion, low productivity areas, lithology, seismic resolution, and stimulation effectiveness. Historically, production from Upper Cretaceous wells could not justify the economic life of the asset. As new fracturing technology evolved in recent years, the re-development focused on replacing old, vertical/deviated one-stage stimulations low producing wells with horizontal, multi-stage hydraulic fractured wells. The project team integrated various disciplines and approaches by re-processing old seismic to improve resolution and signal, integrating sedimentology studies using cores, XRF, XRD and thin section analysis with petrophysical evaluation and quantitative geophysical analyses, which then will provide properties for geological and geomechanical models to optimize well planning and fracture placement. Seven wells drilled since end of 2017 to mid-2021 have demonstrated the value of integration and proper planning in development of a mature field with existing depletion. Optimizing the well and fracture placement with respect to depletion in existing wells resulted in accessing areas with original reservoir pressure, not effectively drained by old wells. Integrating the well production performance with tracer results from each fractured stage, and NMR/Acoustic images from logs enhanced the understanding of the impact of lithofacies on stimulation. This has allowed better assessment and prediction of well performance, ultimately improving well placement and stimulation design. The example from this paper highlights the value of the integrating seismic reprocessing, attribute analysis, production technology, sedimentology, cuttings analysis and quantitative rock physics in characterizing the heterogeneity of the reservoir, which ultimately contributed to "sweet spot" targeting in a depleted reservoir with existing producers and deeper understanding of the development potential in Upper Cretaceous. The 2017-2021 wells contribute to more than 30 percent of the total oil production in the asset and reverse the decline in oil production. In addition, these wells have two to four times higher initial rates because of larger effective drainage area than a single fracture well. Three areas of novelty are highlighted in this paper. The application of acoustic image/NMR logging to identify lithofacies and optimize fracturing strategy in horizontal laterals. The tracers analysis of hydraulic fracture performance and integration with seismic and petrophysical analysis to categorize the productivity with rock types. The optimization of fracture placement considering the changes of fluid and proppant volumes without compromising fracture geometries and avoiding negative fracture driven interactions by customized pumping approach.

Performance Analysis of Infill Wells Adjacent to SAGD Well Pair: Non-Condensable Gas NCG Breakthrough

2021 ◽  
Author(s):  
Mazda Irani ◽  
Aubrey Tuttle ◽  
Jesse Stevenson
Keyword(s):  
Hot Spot ◽  
Pressure Effects ◽  
Productivity Index ◽  
First Year ◽  
Steam Chamber ◽  
Steam Assisted Gravity Drainage ◽  
Flow Control Devices ◽  
Fit For Purpose ◽  
The Common ◽  
The Impact

Summary Late in the life of the Steam Assisted Gravity Drainage (SAGD) process, it has become common practice to drill a single, horizontal infill well (called a “Wedge Well™” by some) in the oil bank located between two mature SAGD well pairs to produce the bitumen that has been heated and mobilized but is unable to be effectively drained by gravity given the largely lateral location relative to that of the SAGD producers. Since this oil bank is surrounded by the large, depleted steam chamber created by the existing well pairs, it requires little heat to mobilize bitumen. One of the challenges, however, in producing infill wells is that non-uniform drainage and local hot spots can be readily created in the first year of their operation, that in many cases require completion retrofits, such as with Flow Control Devices (FCDs), to improve the drainage profile. Installation of FCDs in these wells is quite challenging since the dynamics of the infill wells is changing with time and there is limited time to achieve conformance. To maintain pressure in SAGD chambers the common practice is to inject non-condensable gas (NCG). NCGs, such as methane, which is most common, do not condense in the steam chamber. Some of these NCG can short-cut into the infill through the existing hot-spot. The main reason is that the hot sections of infills are locations that are closer to the SAGD steam chamber, and due to steam condensate encroachment and higher mobility create a pathway for NCG breakthrough. FCDs are designed to promote a more uniform flux distribution along the producer, and exposure to NCG can change the impact of the FCDs. The true hot-spot temperature after NCG injection is decreasing and this can be mistaken as FCD efficiency and steam blocking. In reality, this temperature reduction is due to partial pressure effects associated with NCG encroachment. In this study, a new thermodynamic model is created to explain the NCG encroachment into infill wells, and a new temperature profile along the producer as a function of NCG breakthrough is calculated. The purpose of this work is to create a productivity index (PI) relationship that is fit for purpose for infill wells adjacent to SAGD well-pairs with NCG breakthrough that can primarily be used for analysis and optimization of SAGD FCD completions. This model can also be used to evaluate FCD performance in infill wells pre- and post- NCG breakthrough.

On Subcool Control in SAGD Producers—Part II: Localized-Hot-Spots Effects and Optimization of Flow-Control Devices

SPE Journal ◽  
2019 ◽  
Vol 24 (04) ◽  
pp. 1613-1629 ◽  
Author(s):  
Mazda Irani
Keyword(s):  
Flow Control ◽  
Hot Spots ◽  
Hot Spot ◽  
Large Fraction ◽  
Liquid Pool ◽  
Gas Production ◽  
Differential Pressure ◽  
Steam Chamber ◽  
Flow Control Devices ◽  
Control Devices

Summary At the base of a steam-assisted-gravity-drainage (SAGD) steam chamber, a liquid pool is developed, which is a key component for bitumen production. A producer is placed in the liquid pool, and its production is mainly controlled by its liquid level and the temperature gradient across its depth. A “subcool control” or “thermodynamic steam-trap control” is a typical operating strategy to control steam coning to the producer. Part I of this study (Irani 2018) presented a methodology to evaluate the production rate for a given pressure drawdown and subcool in a SAGD liquid pool; and Part III (Irani and Gates 2018) modified such a formulation for a stability analysis of the Nsolv™ (Nenniger and Nenniger 2000, 2001) process that contained a large fraction of liquid butane. In this study, first, the effect of localized hot spots on well control is formulated as a virtual skin factor in the liquid-pool deliverability equation. The results of this work suggest that a longer hot spot will yield to lower differential pressure and make it more challenging to control the steam breakthrough by choking the well at a given rate. Another key finding is that the steam coning becomes less controllable for higher-permeability reservoirs. Flow-control devices (FCDs) have been used extensively in horizontal wells for conventional oil and gas production to prevent early water breakthrough or gas coning. Although FCDs are commonly installed to prevent steam coning after steam breakthrough and to manage hot spots as retrofit completions by SAGD operators, in recent years, FCDs have been often installed to improve SAGD well-pair performance as part of the initial completion. The benefits associated with this technology in the SAGD industry have been studied with reservoir simulations and validated with field experience, but a theoretical study that discusses the main factors for a correct FCD selection on the basis of operational conditions and reservoir heterogeneity is required. In this study, the liner-deployed FCD and liquid-pool systems are coupled, and two criteria are suggested for a design of liner-deployed FCDs on the basis of the pressure-drop ratio of the FCD relative to the liquid pool (ΔPFCD/ΔPpool) and the coefficient of variation (CoV) of inflow for the liner-deployed-FCD wellbore (CoVFCD). The results of this study show that in higher-permeability reservoirs, the ideal FCD design should have more ports to reduce the differential pressure to flow response. While FCDs will improve inflow conformance relative to completions without FCDs, the effect of permeability in this improvement is minimal. This improvement is larger in applications operating at lower target subcool values. Reducing the target-wellbore subcool value can improve well deliverability twofold: First, FCD-completed wells produce more at lower subcools and, second, reducing the subcool value helps to improve inflow uniformity along the length of the lateral. By effectively removing the fluids available to the producer, the growth of the steam chamber can be maximized through accelerated injection rates.

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