Offshore Production Research Articles

Construction of a sustainability indicators system for offshore oil and gas production units

Production units located in the Brazilian marine environment are responsible for the production of 95.7% of oil and 78.8% of natural gas of Brazil causing economic, environmental, and social impacts motivating us to construct a system of indicators as a tool aimed to improve the sustainable management practice of these production units. To date, one of the tools most used by the oil industry is the sustainability report, oriented by guidelines from international organizations. However, these reports have a corporate character being unable to help the sustainability management of production units’ activities. The indicators were selected based on a systemic approach, using current knowledge on sustainability indicators, together with the survey of aspects relevant to the operation and management of offshore oil and gas production units. This paper describes the proposed indicators and presents the hierarchical structure of the system, built on the economic, environmental, social, and operational dimensions. The application of the proposed system of indicators, based on multicriterial and multiple decision-making analyses, validates a complex decision process, providing improved sustainable management of offshore production units by identifying points for which the necessary measures and actions can be implemented. Keywords: offshore oil and gas production; sustainability indicators; multicriteria and multiple decision-making analyses.

Model-free [formula omitted] tracking control for de-oiling hydrocyclone systems via off-policy reinforcement learning

In offshore Oil and Gas production, it is important to ensure the quality of discharge water meets government regulations; the de-oiling hydrocyclone system is important for this kind of water treatment. Hydrocyclone’s de-oiling performance is very sensitive to the inflow variation, which is often introduced by the upstream three-phase separator’s operation. Thereby, the coordination control of both the separator and hydrocyclone turns to be crucial. Many model-based control methods can be employed for handling this coordination if mathematical models of the considered systems are developed. However, to develop models of these interacted systems is far more than trivial, with respect to the situation that each offshore de-oiling installation at different fields is a kind of tailor-made solution. Thereby, instead of using conventional model-based control design methods, this paper investigates the reinforcement-learning-based H∞ control method for synthesizing an advanced model-free control solution for the coordination control of the separator’s (water) level and hydrocyclone’s Pressure-Drop-Ratio (PDR). The H∞ tracking control is formulated as a 2-player zero-sum differential game and derived by employing an off-policy reinforcement learning algorithm based on state feedback and output feedback, respectively. Stability and optimality of the proposed solution are analyzed. Finally, simulation studies demonstrate the effectiveness of the proposed solution.

Kyoto Protocol and global value chains: Trade effects of an international environmental policy

Deepening globalization and international fragmentation of production (IFP) have provided an appropriate foundation for offshore production processes to exploit comparative advantage wherever possible. Unilateral environmental regulations can increase the outsourcing probability of polluting production processes in regions with looser environmental regulations and can consequently alter trade patterns by changing comparative advantage. The Kyoto Protocol (KP) is considered as one of the international but unilateral environmental regulations for coping with climate changes. This protocol was implemented to mitigate emissions in industrial economies, and its potential side effects such as production relocation have always been controversial. Therefore, this study aimed to estimate the impacts of the KP on trade patterns of the ratifying countries within the context of global value chains (GVCs). For this purpose, the difference-in-differences (DiD) regression and the generalized synthetic control method (GSCM) were used to model the panel data during 1990–2017. The estimation results indicated that the KP ratification decreased the forward participation of the committed countries, while increased their backward participation. As a result, it deepened their relative downstream positions in the GVCs. Accordingly, the KP reduced the share of intermediate goods and services exports in committed countries that ratified KP but increased the share of foreign intermediate goods and services in their exports. In addition, some environmental implications and outcomes of these results, especially for the Paris Agreement, were discussed.

Study of Ultrasonic Logs and Seepage Potential on Sandwich Sections Retrieved from a North Sea Production Well

Summary Important functions of well cement are to provide zonal isolation behind casing strings and to mechanically support and protect the casing. Experience suggests that many wells develop integrity problems related to fluid migration or loss of zonal isolation, which often manifest themselves in sustained casing pressure (SCP) or surface casing vent flows. Because the characteristic sizes of realistic migration paths are typically only on the order of tens of micrometers, detecting, diagnosing, and eventually treating migration paths remain challenging problems for the industry. As part of the recent abandonment operation of an offshore production well, sandwich joints comprising production casing, annulus cement, and intermediate casing were cut and retrieved to surface. Two of these joints were subjected to an extensive test campaign, including surface relogging, chemical analyses, and seepage testing, to better understand the ultrasonic-log response and its potential connection to rates of fluid migration. One of the joints contained an apparently well-defined top of cement (TOC) with settled barite on top. Although the settled material initially provided a complete seal against gas flow, the sealing capability was irreversibly lost as part of subsequent testing. The two joints have effective microannuli sizes in the range of tens of micrometers, in agreement with previous reports on SCP buildup in wells. On a local scale, however, we observed significant variations in cement quality from both the log results and the seepage testing. Further, we found qualitatively very good correlations between seepage-test results and the log results for the bond between cement and casings. The best bonded cement was found directly above a production casing collar, where a short segment of well-bonded cement prevented measurable steady-state seepage of nitrogen. Additional tests involving internal pressurization of the production casing suggested that certain annular-seepage characteristics are well-described by an effective microannulus at the cement/casing interfaces. We consider the two sandwich joints to be highly representative and relevant for similar mature wells that are to be abandoned.

Current Challenges and Advancements on the Management of Water Retreatment in Different Production Operations of Shale Reservoirs

Nowadays, water savings on industrial plants have become a significant concern for various plants and sections. It is vitally essential to propose applicable and efficient techniques to retreat produced water from onshore and offshore production units. This paper aimed to implement the PFF (Photo Fenton Flotation) method to optimize the water treatment procedure, as it is a two-stage separation technique. The measurements were recorded for the HF (hydraulic fracturing) and CEOR (chemically enhanced oil recovery) methods separately to compare the results appropriately. To assure the efficiency of this method, we first recorded the measurements for five sequential days. As a result, the total volume of 2372.5 MM m3/year of water can be saved in the HF process during the PFF treatment procedure, and only 20% of this required fresh water should be provided from other resources. On the other hand, the total volume of 7482.5 MM m3/year of water can be saved in CEOR processes during the PFF treatment procedure, and only 38% of this required fresh water should be provided from other resources. Therefore, the total water volume of 9855 MM m3 can be saved each year, indicating the efficiency of this method in supplying and saving the water volume during the production operations from oilfield units.

Could a new Scottish CO2 transport and storage industry deliver employment multiplier and other wider economy benefits to the UK economy?

In 2021, the UK Government commenced a ‘cluster sequencing’ initiative to identify early movers in delivering carbon transport and storage (T&S) services to proximate regional industry clusters with capture potential. A Scottish proposition focussed primarily on linking the Grangemouth industry cluster to North Sea storage, and the potential to transition Oil and Gas industry capacity to deliver CO2 T&S has devolved policy support. This is in terms of potential to transition and create new direct industry and supply chain jobs, set against risks of displacing jobs in different sectors and regions of the UK. We introduce a Scottish CO2 T&S industry to a UK multi-sector economy-wide model, assessing the extent of potential expansion and job creation in the presence of supply-side and funding constraints. We find that large employment ‘multiplier’ gains registered in previous studies only apply over the very long term and in the absence of such constraints. Crucially, any need to recover demands on the public purse via socialisation of costs severely constrains possible gains, while imposing ‘polluter pays’ leads to net economy-wide contractions triggered by competitiveness losses concentrated in Scottish cluster industries, leading to offshoring of production and jobs, potentially skewed within the localities hosting the clusters.

Onshore, offshore or in-turbine electrolysis? Techno-economic overview of alternative integration designs for green hydrogen production into Offshore Wind Power Hubs

Massive investments in offshore wind power generate significant challenges on how this electricity will be integrated into the incumbent energy systems. In this context, green hydrogen produced by offshore wind emerges as a promising solution to remove barriers towards a carbon-free economy in Europe and beyond. Motivated by the recent developments in Denmark with the decision to construct the world's first artificial Offshore Energy Hub, this paper investigates how the lowest cost for green hydrogen can be achieved. A model proposing an integrated design of the hydrogen and offshore electric power infrastructure, determining the levelised costs of both hydrogen and electricity, is proposed. The economic feasibility of hydrogen production from Offshore Wind Power Hubs is evaluated considering the combination of different electrolyser placements, technologies and modes of operations. The results show that costs down to 2.4 €/kg can be achieved for green hydrogen production offshore, competitive with the hydrogen costs currently produced by natural gas. Moreover, a reduction of up to 13% of the cost of wind electricity is registered when an electrolyser is installed offshore shaving the peak loads.

Spatially explicit life cycle assessment of fish: comparison of local vs imported provision in Wisconsin

Abstract The global fish supply chain handles ∼179 million tons of product annually (as in 2018). Transportation and distribution are an important part of fish supply chain, as fish and shellfish are one of the largest globally traded food commodities with a trading value of ∼$153 billion in 2017. Here we show that disregarding the environmental impacts of fish transportation, either land transit or flight, neglects a noteworthy portion of total fish provisioning environmental impacts. We identified that local fish provision, considering (1) all Wisconsin counties as production points, (2) cities of Chicago, Milwaukee, and Minneapolis as consumption points, and (3) effective, semi-effective, and ineffective space heating approaches, has significantly lower environmental impacts than imported fish provision, considering flight transportation from offshore production points. Meaning the necessity to elevate local fish production capacity to enhance the environmental sustainability of fish provision is essential, despite potential elevated heating demands for cold-weather aquaculture.

Bayesian network modelling provides spatial and temporal understanding of ecosystem dynamics within shallow shelf seas

Understanding ecosystem dynamics within shallow shelf seas is of great importance to support marine spatial management of natural populations and activities such as fishing and offshore renewable energy production to combat climate change. Given the possibility of future changes, a baseline is needed to predict ecosystems responses to such changes. This study uses Bayesian techniques to find the data-driven estimates of interactions among a set of physical and biological variables and a human pressure within the last 30 years in a well-studied shallow sea (North Sea, UK) with four contrasting regions and their associated ecosystems. A hidden variable is incorporated to model functional ecosystem change, where the underlying interactions dramatically change, following natural or anthropogenic disturbance. Data-driven estimates of interactions were identified, highlighting physical (e.g. bottom temperature, potential energy anomaly) and biological variables (e.g. sandeel larvae, net primary production) to be strong indicators of ecosystem change. There was consistency in the physical and biological variables, identified as good indicators in three of the regions, however the shallower region (with depths < 50 m, that is targeted for static offshore wind developments) was the most dissimilar. The use of contrasting regions provided useful insights on responses linked to ecosystem disturbances and identified the top predators as better indicators for each region, with the harbour porpoise being a particularly valuable indicator of ecosystem change across most regions. Another important finding was the dramatic changes in the strength of many interactions over time. This suggests that physical and biological indicators should only be used with additional temporal information, as changes in strength led to the identification of two potentially significant periods of ecosystem change (after 2005 and after 2010), linked to physical pressures (e.g. cold-water anomalies, seen in bottom temperatures; salinity changes, seen in the potential energy anomaly) and primary production changes. The hidden variable also modelled a change in the early 2000s for all the regions and identified maximum chlorophyll-a and sea surface temperature as some of the better indicators of these ecosystem changes.

Development of a Robot for In-service Radiography Inspection of Subsea Flexible Risers

The extreme operational environmental conditions and aging conditions of subsea structures pose a risk to their structural integrity and is critical to their safety. Nondestructive testing is essential to identify defects developing within the structure, allowing repair in a timely manner to mitigate against failures that cause damage to the environment and pose a hazard to human operators. However, to be cost effective, inspections must be carried out without taking the risers out of service. This poses significant safety risks if undertaken manually. This paper presents the development of an automated inspection system for flexible risers that are used to connect wellheads on the seafloor to the offshore production and storage facility. Due to the complex structure of risers, radiography is considered as the best technique to inspect multiple layers of the risers. However, radiography inspection, in turn, requires a robotic system for in-situ inspection with higher payload capacity, precise movement of source and detector which is able to withstand an extreme operational environment. The deployment of a radiography inspection system has been achieved by developing a customized subsea robotic system called RiserSure that can provide precise scanning motion of a gamma ray source and digital detector moving in alignment. The prototype has been tested on a flexible riser during shallow water sea trials with the system placed around a riser by a remotely operated vehicle. The results from the trials show that the internal inner and outer tensile armor layer and defects in the riser can be successfully imaged in real operational conditions.

A Diode-MMC AC/DC Hub for Connecting Offshore Wind Farm and Offshore Production Platform

A diode rectifier-modular multilevel converter AC/DC hub (DR-MMC Hub) is proposed to integrate offshore wind power to the onshore DC network and offshore production platforms (e.g., oil/gas and hydrogen production plants) with different DC voltage levels. The DR and MMCs are connected in parallel at the offshore AC collection network to integrate offshore wind power, and in series at the DC terminals of the offshore production platform and the onshore DC network. Compared with conventional parallel-connected DR-MMC HVDC systems, the proposed DR-MMC hub reduces the required MMC converter rating, leading to lower investment cost and power loss. System control of the DR-MMC AC/DC hub is designed based on the operation requirements of the offshore production platform, considering different control modes (power control or DC voltage control). System behaviors and requirements during AC and DC faults are investigated, and hybrid MMCs with half-bridge and full-bridge sub-modules (HBSMs and FBSMs) are used for safe operation during DC faults. Simulation results based on PSCAD/EMTDC validate the operation of the DR-MMC hub.

Effect of Heat Treatment Conditions on Corrosion Resistance of 0.28C-1.4Mn-0.3Si-0.26Cr Steel with Nb, Ti, and V Microadditions.

The article presents the results of the research on the influence of heat treatment conditions on corrosion resistance of newly developed HSLA-type (High Strength Low Alloy) steel in selected corrosive environments. Laboratory tests were carried out with using a salt spray chamber, enabling the continuous spraying of brine mist (5% NaCl) during 96 h under high humidity conditions. Additionally, as part of corrosion experiments, tests were carried out using the gravimetric method, in which the intensity of corrosive processes was measured by the linear corrosion rate. The research conducted revealed that the best corrosion resistance was noted for steel with a high-temperature tempered martensite microstructure. Investigated 0.28C–1.4Mn–0.3Si–0.26Cr steel with Nb, Ti, and V microadditions can be used in offshore drilling constructions and production platforms exposed to salts present in sea water, chlorides, sulfates, carbonates, and bromides, among others.

NIGERIA DEEP OFFSHORE INLAND BASIN PRODUCTION SHARING CONTRACT ACTS: EVALUATING CONTRACTOR’S TAKE

Value-focused thinking is often designed to focus our decision on the essential activities that must occur prior to solving a decision problem. This approach was adopted by the Nigerian government in the fiscal legislation for Deep Offshore and Inland Basin Production Sharing Contract (DOIBPSC) Act enacted in 1999 and the subsequent amendment of 2020. One major item of interest in the amended Act is the introduction of royalty by price to enable the government to capture windfall in high oil price spike. This study evaluates the new fiscal regime to ascertain its attractiveness and impact of contractor take. Four features (royalty, cost recovery, tax oil, and profit oil) of the PSC contract terms were used to determine contractor and government takes from the transactions. This study adopted the full range of oil prices captured in the amended DOIBPSC Act in addition to the current market price of oil estimation. Six ranges of oil price ($ 20/bbl, $ 30/bbl, $ 40/bbl, $ 80/bbl, $ 120/bbl, $ 160/bbl) were used to cover the five royalty sliding scales adopted in the amended DOIBPSC and the current oil price during this study which is ≤ $ 20/bbl. From the econometric analysis, estimates from the unit root tests revealed that the time series data are mixture of I(0) and I(1) series. The ARDL/bound cointegration test result shows that all the integrated variables are cointegrated at a 5% level. Analysis of the impact of the price sliding royalty regime on the contractors' take shows that in both the long run and the short run, the price sliding (royalty by price) regime had a negative impact on the contractors' take. The short-run impact of the royalty level and the regime change on the contractor's take is high and significantly negative. This is expected as the design of the royalty regime is based on long term benefits. Keywords: Deepwater fiscal system; Royalty regimes; Production sharing contract; Oil and Gas; Long and short runJEL Classifications: P28, O22, O38DOI: https://doi.org/10.32479/ijeep.11244

Accelerating deployment of offshore wind energy alter wind climate and reduce future power generation potentials

The European Union has set ambitious CO2 reduction targets, stimulating renewable energy production and accelerating deployment of offshore wind energy in northern European waters, mainly the North Sea. With increasing size and clustering, offshore wind farms (OWFs) wake effects, which alter wind conditions and decrease the power generation efficiency of wind farms downwind become more important. We use a high-resolution regional climate model with implemented wind farm parameterizations to explore offshore wind energy production limits in the North Sea. We simulate near future wind farm scenarios considering existing and planned OWFs in the North Sea and assess power generation losses and wind variations due to wind farm wake. The annual mean wind speed deficit within a wind farm can reach 2–2.5 ms−1 depending on the wind farm geometry. The mean deficit, which decreases with distance, can extend 35–40 km downwind during prevailing southwesterly winds. Wind speed deficits are highest during spring (mainly March–April) and lowest during November–December. The large-size of wind farms and their proximity affect not only the performance of its downwind turbines but also that of neighboring downwind farms, reducing the capacity factor by 20% or more, which increases energy production costs and economic losses. We conclude that wind energy can be a limited resource in the North Sea. The limits and potentials for optimization need to be considered in climate mitigation strategies and cross-national optimization of offshore energy production plans are inevitable.

Carbon Leakage: The Impact of Asymmetric Regulation on Carbon‐Emitting Production

Regions with carbon emission regulations bear the risk of “carbon leakage” if local producers shift production capacity to an unregulated region. We investigate the problem for a producer subject to geographically asymmetric emission regulation with uncertain future emission price. The producer has two ex ante options to lower its compliance cost: investing in clean production technology in the regulated region and building production capacity in the unregulated region. The producer determines its production quantities ex post, after emission price uncertainty is resolved. We study two anti‐leakage policies, Border Tax (BT) and Output‐Based Allocation (OB), where the former adopts a “stick” approach that penalizes offshore production and the latter adopts a “carrot” approach that grants free emission allowances for production in the regulated region. First, we show that the emission price uncertainty can exert opposing effects in the absence of an anti‐leakage policy: When the expected emission price is low (high), a higher uncertainty aggravates (mitigates) carbon leakage. Second, through a comprehensive comparison, we highlight that while both BT and OB are able to reduce carbon leakage, BT has a stronger effect in both the regulated and unregulated regions in multiple dimensions, especially when the carbon leakage risk is high. Third, we find that a higher emission price uncertainty weakens the effect of both BT and OB. We therefore suggest that emission price uncertainty should be accounted for when formulating anti‐leakage policies. Finally, we extend our analysis to a competitive case and find that the superiority of BT relative to OB is enhanced.

INTELLIGENT PRODUCTION PLANNING AND OPTIMISATION TOOL FOR GAS PROCESSING COMPLEX

Structured production planning is very important to achieve good financial performance in the oil and gas industry. This is especially crucial in an integrated oil and gas supply chain which encompasses feed gas supply, gas processing plants, and petrochemical plants. In the current offshore production climate, the nature of feed gas qualities has evolved. Gas from offshore fields has progressed from having minimal to much higher CO2 content, exceeding the CO2 limits of existing gas processing plants. It is generally impossible to curtail productions from high CO2 gas fields, leading to a loss of revenue. Optimised blending of the feed gas sources is therefore vital to adjust to this changing environment. An intelligent production planning tool was designed to meet the multiple objectives of a gas plant and optimise production. The sales gas demand must first be met based on available feed gas supply and individual plant availability and reliability. Economic factors such as maximising profit from by-products were also factored in by ranking the loading of each processing plant and prioritising plants with higher recovery. Planning strategies were also tailored to each plant’s unique operational limits and turndowns, modes, and challenges. Combining these complex objectives and constraints into a powerful optimisation tool allows a new level of connected intelligence in the production planning of the gas processing complex. The innovative optimisation tool was officially released in 2019 and is currently utilised by production planners in different modes: long-term (5-year duration), medium-term (90 days), and daily operational planning. The planning tool was also designed to be digital-ready and equipped with much improved automation and robustness to embrace the digital transformation agenda. These optimised workflows would improve efficiency and ultimately result in better production planning and decision-making by plant personnel.&#x0D; Keywords: Production planning

What difference has the Cullen Report made? Empirical analysis of offshore safety regulations in the United Kingdom's oil and gas industry

Anecdotal evidence from the United Kingdom's offshore oil and gas industry indicates that risk-based safety regulations, introduced in the aftermath of the 1988 Piper Alpha disaster which killed 167 offshore workers, have improved safety outcomes such as reducing fatalities and dangerous occurrences. However, the empirical dimensions of this supposed improved safety record in the literature is scanty. This paper explores the relationship between the safety regulatory regime and safety outcomes in the UK offshore oil and gas industry from 1995 to 2011 using multivariate regression analysis based on the generalized linear modelling framework. We assess the trend and impact of the regulatory changes implemented through the safety case regulations on major hazard risk indicators such as hydrocarbon releases controlling for technical factors such as type of offshore facility, facility location, water depth, production levels, and external factors such as oil prices, acting as a measure of the prevailing macroeconomic activity level. The results show a statistically significant industry-wide decline in hydrocarbon releases between 1995 and 2011 (average marginal effects), after controlling for location, water depth, installation type, installation age and other factors. This reflects both the commitment of operating companies and the regulator to reducing major accident hazards in line with the principles underlying the safety case regime. Other offshore jurisdictions could focus major accident reduction efforts predicated on goal-setting safety case principles which identify key safety-critical elements of an oil and gas installation and put in place risk-based mitigation measures.

Experiments and mechanistic modeling of viscosity effect on a multistage ESP performance under viscous fluid flow

Assembled in series with multistage, Electrical Submersible Pumps (ESP) are widely used in offshore petroleum production due to the high production rate and efficiency. The hydraulic performance of ESPs is subjected to the fluid viscosity. High oil viscosity leads to the degradation of ESP boosting pressure compared to the catalog curves under water flow. In this paper, the influence of fluid viscosity on the performance of a 14-stage radial-type ESP under varying operational conditions, e.g. rotational speeds 1800–3500 r/min, viscosities 25–520 cP, was investigated. Numerical simulations were conducted on the same ESP model using a commercial Computational Fluid Dynamics (CFD) software. The simulated average pump head is comparable to the corresponding experimental data under different viscosities and rotational speeds with less than ±20% prediction error. A mechanistic model accounting for the viscosity effect on ESP boosting pressure is proposed based on the Euler head in a centrifugal pump. A conceptual best-match flowrate QBM is introduced, at which the impeller outlet flow direction matches the designed flow direction. The recirculation losses caused by the mismatch of velocity triangles and other head losses resulted from the flow direction change, friction loss and leakage flow etc., are included in the model. The comparison of model predicted pump head versus experimental measurements under viscous fluid flow conditions demonstrates good agreement. The overall prediction error is less than ±10%.

Scenarios for offshore wind power production for Central California Call Areas

AbstractIn response to the growing interest in offshore wind energy development in California, the U.S. Bureau of Ocean Energy Management delineated three Call Areas for potential leasing. This study provides a comprehensive characterization and comparison of offshore wind power potential within the two Central California Call Areas (Diablo Canyon and Morro Bay) using 12‐ and 15‐MW turbines under different inter‐turbine spacing and wind farm size scenarios. Our analysis shows similar daily and seasonal patterns of wind power produced within the Call Areas, which peak in spring and during evening hours. Per‐turbine power production is higher in the Morro Bay Call Area due to slightly higher hub‐height wind speeds, whereas total power production is higher in the Diablo Canyon Call Area due to its larger size. Turbine type had a negligible impact on average power production per‐unit‐area because while larger turbines produce more power, they require greater inter‐turbine spacing. Combined power production from the two fully built out Call Areas could equal nearly a quarter of California's current annual electrical energy production. A commercial‐scale wind farm with a realized power output of 960 MW would require a footprint of at least half of the Morro Bay Call Area or at least a quarter of the Diablo Canyon Call Area. These results provide guidance on offshore wind development over the Central California Coast, and the framework demonstrated here could be applied to other wind data sets in other regions.

Influence of Flow Properties on Gas Productivity in Gas-Hydrate Reservoirs: What Can We Learn from Offshore Production Tests?

Gas hydrates are expected to be an energy resource in this century. Many countries, such as the United States, China, India, and Japan, have explored potential reservoirs and promising production m...