bluuebunny/crossref_metadata_2025 huggingface dataset:
Understanding the Complex Channel Sand Reservoir from High-Definition Oil-Base Mud Microresistivity Image Logs: Case Study from Junggar Basin
Authors: Zhang Zengbao , Xu Wei , Liu Yanhui , Zhou Guangqing , Wang Deshun , Lyu Jainbo , Sun Bo , Feng Jiansheng , Xin Zhong Bin , Liu Bo , Li Shenzhuan , Liang Cai , Wang Wei , Guan Hui , Yu Daiguo , Wei Guo , Sultan Gamal
Published: April 2022

This study examines an important channel sand reservoir in the Junggar Basin, which has a reservoir quality that varies greatly in the vertical and horizontal directions due to the presence of tight sandstones deposited under different sedimentary conditions. Studies confirmed that the high-energy sandstone deposits have good porosity and permeability based on the core data. The channel sand is 20 m to 30 m thick in the Qigu formation and can be divided into three to four channels. Identifying and characterizing the high-energy sandstone "sweet spots" was the objective of this case study.

In order to find the sweet spot in this reservoir, high-definition oil-base mud microresistivity image logs were acquired in five exploration wells. The image logs made it possible to identify the different kinds of sandstone reservoirs based on sedimentary structure and texture. Parallel bedding, deformed bedding, cross bedding, and massive bedding were all identified. The paleocurrent energy was from high-to-low and from bottom-to-top in a single channel sand body. The core and production data validated the reservoir qualities, which were identified from the sedimentary features.

The channel sand was divided into three to four multistory sand bodies based on image logs. As a result, the typical channel-levee system—composed of massive bedding, cross-bedding and parallel bedding features—was revealed. The massive bedding was mainly at the bottom of the single channel system, surmounted by high-angle cross-bedding, and then finally the parallel bedding intervals. The paleocurrent energy changes from high-to-low vertically within the single channel system. Based on the open-hole and image logs, two types of sweet spots were identified: massive bedding sandstone and high-angle cross-bedding sandstone. These two types were deposited in a high-energy environment which formed the potential sweet spot in the channel complex. The massive bedding intervals, which are mainly in the channel bottom, when cemented by calcite or clay, will become tight sometimes. The high-angle cross-bedding sandstone and uncemented massive-bedding sandstone were the potential target zones for the horizontal well.

This case study will show the interpretation of sedimentary features in the channel sand reservoir based on high-definition image logs, to provide a comprehensive understanding of the geologic features that differentiate reservoir quality. The identification of cross-bedding in the channel sand provided a new way to predict possible tight sandstone sweet spots that can help to design horizontal wells.
Development of a High-Voltage Connector System for Floating Offshore Wind Turbines Using Field Proven Oil and Gas Technology
Authors: Plant Christopher
Published: April 2022

This paper will detail the process of developing a 36/60(72,5) kV high voltage wet mate and dry mate connector system, designed to meet the requirements of floating offshore wind turbines, and utilizing new and proven subsea technology developed to meet the requirements of critical reliability subsea applications.

The paper will consider the state of the art for subsea high voltage wet and dry mate connectors before identifying the requirements of the floating offshore wind industry. A technology readiness assessment will be performed to define a technology qualification program for a new solution to meet the requirements of the floating offshore wind industry. The technology qualification program will then be executed to bring a solution to technology readiness level (TRL) 4, according to API 17Q.

This paper will develop a technology readiness assessment for existing high-voltage connector solutions within the oil and gas industry for applications within floating offshore wind, starting with documenting the current state of the art for subsea high-voltage wet and dry mate connectors. The technology readiness assessment will form the basis of an engineering and test program for a new solution for floating offshore wind applications.

This paper will document the engineering and qualification in accordance with the requirements of the floating offshore wind industry as well as established and emerging international and regional standards, such as IEC and IEEE standards.

It is very likely that as the floating offshore wind industry matures, there will be continual development of the requirements and this paper will discuss likely changes in the requirements for high-voltage connector systems for floating offshore wind in the long term.

Within the floating offshore wind industry, there are many different solutions proposed for the floating substructure. The paper will explore the potential advantages and disadvantages that the use of subsea wet and dry mate connectors might bring to floating offshore wind and will consider the full lifecycle of the floating wind farm, with a high focus on risk and cost during installation, reliability, and maintenance.
In-Situ Stress Models for an Anisotropic Rock Formation Using Well Log Sonic Data - A Comparison of Different Approximations
Authors: Hachem Dany , Wong Sau-Wai
Published: April 2022

The evaluation and estimation of in-situ stress regimes are vital in many subsurface engineering processes such as borehole stability in deep well drilling, hydraulic fracturing design, water injection for pressure maintenance, geothermal recovery, and geological carbon sequestration.

For complex lithology and highly laminated rock formations such as an organic-rich shale gas reservoir or a clay-rich overburden caprock, the anisotropic mechanical rock properties can be described as transversely isotropic with a vertical symmetry axis - the so-called vertical transverse isotropic (VTI) models.

The use of the poro-elasticity concept is one of the most common approaches in the determination of in-situ stresses. It assumes a porous rock medium and uses elastic parameters, vertical stress, and pore pressure for horizontal stress determination. The application is relatively trivial for isotropic rocks as the elastic parameters can be estimated/obtained from compressional and shear velocity waves available from well logs. However, for anisotropic rocks with transverse isotropy, the approach becomes more complicated. Only three of the five unknown independent stiffness coefficients can be calculated from well logs, requiring advanced sonic logging tools in vertical wells to provide compression, shear and Stoneley waves. The remaining two coefficients involve various assumptions and empirical correlations for their approximations, with no clear consensus or indication as to which is more valid or more accurate than the other.

In this paper, we examine 3 different well-known models and assumptions to derive the VTI minimum in-situ stress for a deep anisotropic rock formation. Specifically, we examine a class of established models and a more recently developed lab-based regression/empirical model. The strengths and weaknesses of each approach are discussed, and a straightforward workflow is proposed. This workflow integrates all possible constraints on the critical stiffness coefficients based on data quality and availability and includes a pragmatic approach to calibrating the log-derived in-situ stress profile with field injection data. Here, we adopt a simplified calibration approach and compare its merit to the traditional scheme.
A Construction Method of Complex Fractures in Marine Carbonate Reservoir
Authors: Wang Wenzhi , Yang Guang , Cui Meng , Wang Haige , Zhou Zhou , Kao Jiawei , Liu Yuqing , Wang Lian
Published: April 2022

Marine fractured-vuggy carbonate reservoirare important oil and gas reservoirs in China, the Middle East, and North America. In the development process, it is necessary to connect hydraulic fractures and as many karst cavities as possible, which are the main geological components of oil and gas storage. However, the systematic theoretical of how to build complex fractures in fractured-vuggy carbonate reservoirs is scarce. Facing this situation, this paper presents a method that can improve the accuracy of fracturing effect prediction and optimize fracturing process design parameters so as toachieve the purpose of increasing production. It studies the factors that could affect that connection. It is found that the density of natural fractures and cavitiesin the reservoir is the main factor affecting the fracture propagation shape. Meanwhile, the liquid containing cavitiesin the reservoir will attract or repel the fractures. Furthermore, natural fractures will cause the migration of fracture propagation path and hydraulic fractures are easy to continue to expand along the direction of large natural fractures. This methodology could be used in future studies for the marine fracture–vuggy carbonate formation. In addition, the research conclusion could be used to design and evaluate hydraulic fracturing operation.
A Data Centric Digital Platform for Rigid Pipeline Engineering
Authors: Truche Sylvain , Le Prin Kevin , Ben Abdallah Mohamed , Minguez Matthieu
Published: April 2022

Rigid pipeline engineering, alike most of the engineering activities, has to manage a deep transformation in the way it is performed. This trend is seen throughout the industry. This transformation is driven by the massive introduction and development of digital products and services, which as of today drive what is called a Digital Transformation. The paper briefly provides some insights on how such a transformation is reshaping the current established order in term of organization, schedule, product, processes, human resources, and business strategy. While this transformation is still moving on, a specific focus on Data is getting a massive momentum, as Data is becoming, within a general consensus, a major sought-after assest, a business field on its own.

Based on that new paradigm, the notion of single digital thread is introduced to highlight the need to manage the flow of data which is produced through the different digital products, platforms, or services. In the Company, this notion of a single digital thread is symbolized by Subsea Studio™ (here after called SS) to which the different digital products, platforms and services are connected.

Once such a context is properly defined, the focus is done on the digital platform called Smart Pipeline Design ARENA (hereafter named ARENA) which is to be seen as a product configurator dedicated to rigid pipeline engineering. The authors firstly present what ARENA is about, what ARENA intends to offer and how ARENA is embedded in the digital ecosystem and strategy of the company. To conclude, the authors introduce how the platform and the massive use of Artificial Intelligence algorithms can impact rigid pipeline engineering and more generally improve the business performance. This is achieved providing (i) some insights on the way automation and optimization are implemented in standard engineering process flow and (ii) most importantly the savings which have to be expected in terms of direct engineering cost (i.e. man hours) and technology & procurement cost.
Casing Exit System with No Red Zone Assembly
Authors: Gregurek Philip Matthew , Eidem Morten , Nguyen Tuan Anh , Grindhaug Gaute , Ferdin Valerie , Ali Mohsen , Hern Greg Lee , Munir Waqas
Published: April 2022

This system delivers on improved safety, robustness, and efficiency of a casing exit operation by providing a positive impact in the reduction of carbon emissions. This is possible due to the system's ability to reduce the required time to pick up, deploy, run in hole, install, and to perform the milling operation. The reduction in time in these operations translates to an increase in personnel safety and reduces carbon emissions to the environment. The system furthers the efforts of safety with its ability to combine the traditional required separate clean-out run with the installation run. This substantial time savings and deletion of a separate clean-out operation removes the opportunity of exposing personnel to the risk of potential falling objects, cluttering of the rig floor with additional tools, and the handling of the tools. Traditional whipstock systems utilize a shear bolt as it's mill to whipstock interface, whereas this system uses a self-aligning cylinder that can be assembled on the rig floor or can be pre-assembled in the shop prior to being loaded out. The benefits of being pre-assembled allows for the system to be picked up and directly installed into the well, thus preventing personnel exposure to dangerous pinch points. Traditional whipstock systems are limited to a run-in hole rate of two minutes per stand. The limitation of the slow run-in rate promotes delays in the progression of subsequent tasks. The long durations while running the traditional system in hole can lead to distractions and complacency resulting in injuries due to lack of focus. The system can prevent failed runs and reduced trips with its combination of redundant activated anchor and mill to whipstock interface, the anchor being configurable in either hydraulic or annular activation, can also be activated by setting down on a bridge plug, fish, or cement plug. With the use of the connector style whipstock, the anchor can be dragged up hole and reoriented if needed to the original kickoff point (KOP). This eliminates the necessity to pull out of hole and to re-run due to a failure in setting the whipstock. Thus, preventing unnecessary changes to the casing exit operation and decreasing handling of tools by personnel.
Assessment of the Potential for Hydrogen Production from Bottom Fixed Offshore Wind in Uruguay
Authors: Tomasini Juan , Gristo Pablo , Ferro Santiago , Novo Rodrigo
Published: April 2022

After having decarbonized almost the entire electricity matrix, the next step in the Uruguayan energy transition includes the development of a hydrogen economy, for which both local and export markets are being considered, based on vast untapped unconventional renewable resources potential onshore and offshore. For ANCAP (NOC), hydrogen is key in the transition to a low-carbon and sustainable energy company, hence initiating several actions including the assessment of the potential for hydrogen production from offshore wind. Leveraging on data and information from offshore oil and gas exploration projects, distinct regions were delineated as the most suitable for the development of offshore green hydrogen production projects both from bottom fixed and floating wind technologies. In this work we present the results of the potential assessment of two regions suitable for bottom fixed offshore wind technologies.

Region 1 is located at the interior waters of the Uruguayan territorial sea at distances longer than 10km from the coast and water-depth ranging from 10 to 30 m. Region 2 is located on the Uruguayan Exclusive Economic Zone at distances longer than 60 km from the coast on water-depth ranging from 20 to 60 m. The assessment of the potential of these regions includes both the power generation and hydrogen production according to stochastic model based on capacity density data from North and Baltic Sea projects, energy requirements for PEM electrolysis technology and capacity factor data specific for offshore Uruguay. Additionally, both regions were evaluated and compared based on other inferred aspects derived from different development concepts, such as social acceptance, OPEX, CAPEX and logistics among others.

Results indicate that Region 1 and Region 2 have potential for power generation of 14GW and 110GW respectively, that corresponds to hydrogen production potential of 1.2Mton/year and 10Mton/year respectively (indicated figures corresponds to mean values). From contrasting both regions on other different aspects, results that Region 1 has advantages regarding CAPEX and OPEX while Region 2 has advantages regarding potential social acceptance and logistic requirements. Calculated hydrogen production potential for both regions represent more than eighty times the equivalent diesel currently consumed in Uruguay for heavy duty transport, demonstrating the relative size of the local market compared with the offshore potential. On the other hand, already announced green hydrogen future requirements for Europe and Asia suggest attractive markets for this kind of developments.

For the first time the potential for hydrogen production from bottom-fixed offshore wind in Uruguay was assessed indicating very attractive results, both technically and economically, for the export market. Results are encouraging as lead to new possibilities to support the next energy transition in the country towards the development of a hydrogen economy.
A New Approach to future FLNG for Offshore Gas Monetization
Authors: Liu Xiaogang , Fu Liping , Ji Xiuyun , Zeng Xiaogang , Chen Guang , Zhang Yuezheng
Published: April 2022

A new approach to future FLNG is presented which will significantly reduce the overall CAPEX, EPCIC schedule, and OPEX compared to past conventional bespoke FLNG designs and project execution methods.

Using a standardized design approach on both FLNG topside and Hull, this new FLNG concept will provide standardized design of liquefaction and process modules with flexible and standardized hull forms and cargo containment systems. This FLNG concept can be deployed around world near shore or offshore with Jetty or Single Point Mooring, such as SSY or an External Turret. The standardization approach enables reduction in the EPCIC cost and schedule so that it becomes a more attractive solution for Gas Monetization.

The paper will describe:

➢ Topside Modularization is based on functionality and Standardized design for easy integration and assembly for various sizes of production capacity and pre-process requirements. ➢ Environmentally friendly approach using highly efficient SMR technology employing aero-derivative gas turbine utilizing waste heat recovery to lower the carbon dioxide footprint. ➢ Patented turbo-expander based NGL recovery process and feed gas booster can provide flexibility in a range of deployment scenarios with standardized design of refrigeration and liquefaction modules. ➢ Embedded Advanced Control (WACTM) with ICSS can significantly reduce the number of operators on board and ultimately achieve unmanned operation. ➢ Proven robust SPB cargo containment system with standardized tank design provides storage for both LNG and LPG that fits standardized hull dimensions. ➢ EPCIC project execution by a single contractor on topside, hull, construction, integration, pre-commissioning, and gas trials to reduce interface, save cost and shorten schedule ➢ Completion of gas trials at LNG terminal before transportation to reduce the cost and risk of onsite commissioning issues.

This new FLNG concept can be applied to a capacity range from 1 MTPA to 4 MTPA with different combination of standardized functional plug-in modules. It can be optimized to accommodate feed gas range from associated to non-associated gas streams, and can be deployed either offshore or near-shore with a standardized hull design adapted for different mooring systems. This new FLNG concept can greatly reduce the risks with project execution and overall schedule, thus providing an ideal solution for Offshore Gas Monetization.
Bismuth Plugs Used to Cap All Wells During the Final Phase of the Valhall DP Abandonment Campaign, Offshore Norway
Authors: Thorstensen Egil , Vadset Kjetil , Straume Martin Knut , Delabroy Laurent , Abdelal Gasser , Carragher Paul , Fulks Jeff , Mason David Leslie
Published: April 2022

A premium bismuth-based alloy plug system has been developed to achieve a gas tight seal in annuli that cannot be achieved with traditional cement plugs, providing a new methodology for abandoning wells. To date, 35 plugs in total have been run in 30 wells, with this technique consented to by the offshore Norway regulator for Valhall conditions.

No surface pumping equipment is needed for this type of plug. The alloy – when molten – has a viscosity like water, but a very high density. It can therefore flow through perforations or section milled windows, with gravity, into the annulus or into multiple annuli. When the alloy solidifies, it expands to create an impermeable seal. The entire process, from melting to solidification, takes place in a matter of minutes and the seal is ready to test within a few hours.

The first at scale programme for abandonment applications has been done in the Valhall field offshore Norway. This was following an extensive plug and alloy development and qualification programme over a 4-year period, working in partnership with the local regulator from the outset. The testing programme demonstrated that the bismuth-based material is, in many ways, superior to cement. Following successful development of a system, a single well in Valhall was selected for a trial and tested for 2 years. Following success in the trial well, the operator extended the application to a total of 30 wells.

Three different tool sizes were required for the campaign. Section milling of inner casings of 13-3/8", 18-5/8" and 20" had to be performed. Significantly shorter lengths for section milling were required as the bismuth plug – set inside the window – contributed to the efficacy of the system. All plugs were set by running on pipe. The tools run in these wells resulted in the world's largest bismuth alloy plug ever deployed with the largest tool (20"x30") weighing in at nearly 16,000 kg (34,000 lbs) and over 9,000 kg (20,000 lbs) of alloy. After the tools were melted downhole, the heater was extracted resulting in a solid bismuth alloy barrier across the wellbore.

Extensive work was done to assess corrosion risk. Numerous tests were done according to industry standards and the bismuth-based plug substantially outperformed Inc 718 and 13Cr L80, thus a substantially longer lifetime is projected than had conventional materials been used.

The authors believe that this technique can – when coupled with appropriate engineering work and in partnership with local regulators – be more widely applied, leading to simpler operations, lower costs and better long term well integrity.
Break-Through in Elimination of High-Frequency Torsional Oscillations through New Damping Tool Proven by Field Testing in the US
Authors: Kueck Armin , Hohl Andreas , Schepelmann Cord , Lam Sui-Long , Heinisch Dennis , Herbig Christian , Kulke Vincent , Ostermeyer Georg-Peter , Reckmann Hanno , Peters Volker
Published: April 2022

The push in the drilling industry for drilling longer wells, and faster and more difficult trajectories leads to increasing challenges with the dynamics of the drilling systems in particular in expensive high end offshore wells. Dynamic effects are more severe and occur more frequently increasing load and damage to tools so that mitigation by dedicated tools or drilling procedures is necessary. Generally, downhole drilling dynamics effects can be categorized by their direction of action. Vibration excited in the axial direction, along the tool axis, mainly originates from the bit rock interaction, e.g. bit bounce (Dykstra et. al. 1994). Vibration in the lateral direction, perpendicular to the tool axis, can be generated from interaction with the borehole wall. Here forward and backward whirl motions are possible. In case of backward whirl the origin can be, for example, the whirling bit (Brett et. al. 1990) or a stabilizer. Low clearance results in high whirl frequencies accompanied by high loads (Oueslati et. al. 2014). The earliest identified torsional vibration phenomenon in the drilling industry is stick-slip where the entire string oscillates with a frequency close to its first eigenfrequency. Due to the drill string length this frequency is low, at usually less than 1 Hz. Due to more advanced dynamics measurement tools (Makkar et. al. 2012, Akimov et. al. 2018, Townsend et. al. 2021) that record data at higher sampling rates, another torsional dynamics phenomenon was identified in recent years: high-frequency torsional oscillations (HFTO) (Jain et. al. 2014, Zhang et. al. 2017). The vibration frequency of HFTO could be identified to be in the range between ~50 Hz to above 400 Hz depending on the bottomhole assembly (BHA) and string configuration. The root cause for this type of vibration is a self-excitation mechanism in the bit-rock cutting process in hard rock, when drilling with PDC bits onshore and offshore (Oueslati et. al 2013, Oueslati et. al. 2014). HFTO can result in high dynamic torque and rotational and tangential acceleration amplitudes stressing the drilling tools.

The combination of high frequencies and high amplitudes can quickly result in fatigue damage on tools and components. Examples are displayed in figure 1. The dynamic torque fatigues the material, and 45-degree cracks occur and grow (Zhang et. al. 2017). The acceleration leads to relative movement due to inertia forces which can vibrate cables off circuit boards or generate "vibration dust" where vibrating parts are in contact which each other.
Simulation of Subgouge Sand Deformations Using Robust Machine Learning Algorithms
Authors: Azimi Hamed , Shiri Hodjat , Mahdianpari Masoud
Published: April 2022

Ice gouging is one of the major menaces to the subsea pipelines crossing the Arctic (e.g., Beaufort Sea) or the non-Arctic (e.g., Caspian Sea) shallow waters. Burial of the sea-bottom-founded infrastructures is regarded as a feasible method for protection of the subsea assets against the ice gouging threat. These pipelines are commonly embedded underneath the deepest ice-scoured records in the area, whereas the pipeline system is still threatened by the ice-induced soil displacement developed into the ice tip owing to the shear resistance of the seabed soil.

Determination of the sub-gouge soil displacements is a governing design factor for the subsea structures in the Arctic offshore that commonly need costly laboratory studies and long-running finite element (FE) analyses to guarantee the operational integrity of the subsea pipeline against the ice-gouging event. Thus, the industry is still seeking more cost-effective, reliable, and faster alternative approaches for simulation of the iceberg-seabed-pipeline interaction process to minimize the collision risk of ice keels with the subsea structures. Recently, the application of machine learning (ML) in different fields has witnessed impressive growth since the ML technology is sufficiently precise, quick, reliable, and cost-effective to model various linear and non-linear problems.

In this study, three robust ML algorithms comprising the Decision Tree Regression (DTR), Random Forest Regression (RFR), and Extra Tree Regression (ETR) models were used for the first time to simulate the iceberg-seabed interaction process in the sandy seabed. Using the parameters governing the ice-seabed interaction mechanism, a set of the DTR, RFR, and ETR models were developed. To verify the ML models, a comprehensive dataset was constructed and the data was divided into two sub-samples including the training (70% of data) and testing (the remaining 30% of the data) datasets. Subsequently, for the DTR, RFR, and ETR models, several analyses such as sensitivity analysis, error analysis, and uncertainty analysis were performed. The conducted analyses demonstrated that the ETR algorithm had a reasonable performance to simulate both horizontal and vertical sub-gouge soil deformations in the sand. The soil depth ratio (y/W) and the horizontal load factor (Lh/γs.W3) had substantial significance to model the horizontal and vertical deformations in the present study.

The presented results provided a good notion of modeling the ice-gouging problem through the ETR algorithm. The outcomes may facilitate proposing new solutions to estimate the sub-gouge soil deformations in the sandy seabed. The present work can also be used for the planning of expensive field, laboratory, and FE simulations and to reduce the expenditures on future studies.
Techno-Economic Assesment for Carbon Capture Techniques
Authors: Poothia Tejaswa , Pandey Gaurav , Mehra Dipti , Rawat Prerna B. S.
Published: April 2022

This paper focuses on a techno-economic analysis for carbon capture technologies with a study of processes that apprise different grades of products purity. The cost evaluation of carbon capture and storage techniques has been discussed. It describes about the cost metrics, carbon storage and transport, aspects of energy supply, maturity, retrofitting cost of these techniques. Therefore, the three leading carbon capture techniques namely: pre-combustion, oxyfuel-combustion and post combustion carbon techniques are enlightened to review the development of carbon capture techniques and their techno economical aspects which can be beneficial for sustainable development. Carbon products streams that are generated by Carbon Capture and Storage (CCS) techniques, are observed to contain the impurities at some level. The effect of these impurities for the efficient and safe storage and transportation of carbon is fundamentally major issue. Acceptability and economic viability in terms of health risks and surrounding environment are also very critical factors. The paper aims to review the various technoeconomical aspects for carbon capturing technologies in industries and different power plants in order to increase the feasibility/efficiency of CO2 storage and transport for promising future.
Geomechanics Helps in Identifying Hydrocarbon Potential and Compaction Disequilibrium of Eocene Reservoirs – Case Study of a Geologically Complex Plateau in South Asia
Authors: Mahmood Azhar , Khan Mohammad Rasheed , Siddiqui Faraz Hasan , Khalid Perveiz , Ahmed Nisar
Published: April 2022

Reservoir geomechanics is essential for cost-effective drilling in complex areas, reducing risks related to wellbore stability problems, and other issues related to abnormal pore pressure, efficient reservoir modeling and enhanced oil recovery (EOR) plans. The information of major sources of overpressure generation like tectonics, under compaction, hydrocarbon accumulation and presence of an effective seal is necessary to apply reservoir geomechanics. The present study comprises of structural interpretation and comparative petrophysical evaluation of the Chorgali Formation with special emphasis on reservoir geomechanics for this Eocene reservoir in an oil field. This field is in the Potwar Plateau, included in the list of areas of the world containing over-pressured sedimentary rock.

The main objective of this research work is to determine the pore pressure using well log data for two wells. In this model sonic transit (DT) time is correlated to recognize the compaction history for more accurate pore pressure prediction and to analyze the dependence of compressional wave velocity on vertical effective stress, stiffness of material and pore pressure. Pore pressure prediction by using well log data is much more affordable and gives continuous and extensive range of data than direct measurement by modular dynamic tester, drill stem test and repeat formation tester, etc. One dimensional (1D) well concentric mechanical earth model (MEM) is developed for reservoir geomechanics of Eocene carbonates.

Seismic interpretation results reveal thrusting and popup structures in the area due to compressional tectonic regime. Petrophysical analysis discloses that the Chorgali Formation has better reservoir characteristics as compared to the Sakesar Formation. Compaction disequilibrium in argillaceous layers and hydrocarbon accumulation in reservoir zones are primary sources of overpressure. The well log-based pore pressure estimation shows good agreement with the in-situ measured formation pressure obtained from modular dynamic tester (MDT). The variation in rock physics properties such as bulk modulus, Young's modulus, shear modulus and Poisson's ratio are also modeled to delineate the high pore pressure zones. Reservoir geomechanics results illustrate that the predicted abnormal pore pressure is mainly due to significant hydrocarbon potential in the Chorgali Formation. On the other hand, shales deposited in the Sakesar Formation during Early Eocene are over-pressured due to compaction disequilibrium.
A Test Rig for Jetted Conductors in Soft Clays
Authors: Fernandes Bernardo Branco Lopes , Pinheiro Arthur Veiga Silvério , Guimarães João Henrique Diniz , Dias Rafael , Cutrim Fabio Sawada , Gonçalves Clemente José de Castro , Danziger Fernando Artur Brasil
Published: April 2022

This paper describes the design, construction and operation of a test rig for jetted conductors in soft clays. The rig was designed to produce repeatable tests under controlled conditions to evaluate the influence of operational jetting procedures on the conductor performance just after installation and at different periods after installation (set-up effect), underdifferent loading conditions. The test drilling rig consists of two main parts: an isostatic supporting structure and a jetting bottom hole assembly (BHA). All parts were designed to emulate real operational conditions found in offshore drilling rigs on a more manageable scale. A 7" (177.8 mm)OD and 6 m long conductor was used for this purpose and a 3.5" (88.9 mm) commercial drilling motor was fitted inside it. The design was such that several combinations of values of bit stick-out and flow rate are easily obtained in the field. The test rig showed up as a powerful tool for geotechnical research in which the influence of some drilling parameters on the axial and lateral bearing capacity of the conductor, such as: bit stick-out, flow rate and set-up can be evaluated.
Towards a Novel Approach to Consider Casing Wear in Well Designs
Authors: Mencaglia Xavier , Cazier Olivier , Feutry Vincent , Almeida Gustavo , Brillaud Loïc
Published: April 2022

This paper deals with an in-depth evaluation of the collapse pressure of a worn pipe (due to the casing wear) using a reliability-based approach (based on a 2D finite element analysis) combined with physical tests. In addition, a novel approach to evaluate the performances of a worn connection is proposed combining 3D FEA and physical tests.

The first step is to determine the maximum wear, due to the contact forces between the drillstring and the inner wall of the pipe while drilling. A stiff-string torque and drag model with contact management allows a very accurate estimation of these forces at each step of the well construction process, and the cumulative mechanical work is calculated at each cross section of the well. A wear model is then applied: the induced 3D wear is calculated, and a predicted maximum wear profile is obtained.

This maximum wear is incorporated in the pipe collapse reduction factor evaluation (referred to as CRF) and in the worn connection evaluation envelope (referred to as worn CEE) assessment. For the pipe, a 2D model has been developed. This model is fully parametric, and a variety of parameters can be changed such as: the ovality, the eccentricity, the pipe OD/t ratio, the tool joint diameter, the position of the wear groove, etc. A large DoE has been launched to evaluate the CRF of each individual pipe. This cloud of points allows for determining an equation to give a CRF in function of the casing wear level. This equation integrates the scattering that will be found in the reality considering a pipe population. Some physical tests were performed to cross-check with the equation. The equation shows a less severe CRF than the one computed with the API uniform wear model. For the connection, a 3D FEA model including the casing wear groove is created to evaluate the local stress gradient in the groove. The connection studied is a VAM® SLIJ-II. In addition, some physical tests (based on the API RP 5C5:2017) were performed to check the remaining performances of the connection and to correlate with the FEA. Through the test, the VAM® SLIJ-II 14" 115.00# 125ksi has demonstrated that the initial CEE was maintained during multiple rounds of a Series A with both 5% and 10% wear.

The litterature is centered on the casing wear of pipes comparing the API uniform wear model to other approaches such as analytical formulation or finite element analysis. In this paper, a casing wear profile is estimated with a stiff string model, and the CRF for the pipe is calculated thanks to a reliability-based approach. The important novelty is the assessment of a worn CEE on the VAM® SLIJ-II using a 3D FEA model and some tests.
Implementing A New Spacer System Capable of Curing Partial Losses Prior to Cementing While Depicting Remarkable Fluid Compatibilities
Authors: Shamsan Abdulmalek Ahmed , Nino Adriana Contreras , Hugentobler Kory , De La Cruz Sasso Alejandro , Zuleta Rodny Masoud
Published: April 2022

A cleaning system that effectively displaces movable and immovable mud from the wellbore prior to cementing is key for a successful cementing job and for long term zonal isolation. If in addition, the cleaning system can help in minimizing losses while showing proper compatibilities with mud and cement both, this will provide another assurance for a competent cement sheath in the wellbore. This new spacer system was tailored as per the actual wellbore conditions for Saudi operations.

To analyze the behavior of the new spacer system under different conditions, fluid compatibilities were performed with diverse drilling fluids and cement slurries. The stability of the new spacer was also verified under static and dynamic conditions. Furthermore, this spacer was tested with and without Lost Circulation Material (LCM) through different slot sizes ranging from 500-5000 microns along with a Particle Plugging Apparatus (PPA). This test was used in determining the spacer's capability to plug the slots under different pressure and temperature ranges.

In this study, spacer design was optimized to maintain the rheological and density hierarchy requirement between three fluids - drilling fluid, spacer, and cement slurry. Spacer design was tailored to maintain the above-mentioned hierarchies at both surface and downhole temperatures. It was found that the new spacer system has improved compatibility results with different drilling muds and cement slurry systems even without adding any additional viscosifier agents. The tailored spacer proved its stability under high pressure high temperature (HPHT) conditions using a consistometer with no settling and zero free fluid. In addition, it shows to effectively plug a 500-micron slot disk and was able to seal up to 5000 microns when LCM was added across different pressure ranges (100, 500 and 1000 psi). In addition, field trials for wells encountering dynamic and static losses were performed where spacer with LCM was pumped after considering critical flow path and minimum flow area restrictions. As a result, the new spacer proved to be compatible at multiple densities, demonstrated its ability to bring cement to desired depths, and helped in improving Cement Bond Logs (CBLs).

The application of this engineered spacer system is extremely valuable for the fields having low fracture density formations. Pumping this spacer, will not only help in the effectively cleaning of wellbores prior to receiving the cement but also in forming a seal to reduce any loss circulation issues. This will help in bringing the top of cement (TOC) to the desired depth and ensuring placement of a dependable barrier throughout the life of the well.
Offshore Co-Produced Critical Minerals and Geothermal Energy Generation
Authors: Nash Susan Smith
Published: April 2022

Scope

This paper presents the results of a study to determine the potential for coproduced critical minerals and geothermal energy generation in offshore production. The objective was to focus on high temperature produced water in locations likely to contain critical minerals such as lithium, rare earth elements (REEs), platinum group metals, arsenic, and others. The scope is global, and the offshore locations graded to prioritize in terms of geothermal energy and concentration of critical minerals.

Method

The method involved studying the tectonic history of the offshore production of the world and conducting reconnaissance basin analysis to create general maps of heat and location of critical minerals. A study of all publications that included information about the geochemical composition of reservoir fluids as well as samples / cores was also incorporated. Where available, geothermal information was gained by collecting the bottomhole temperatures of producing and test wells.

Results

The preliminary results indicate that some offshore production does have the potential to be converted to producers of geothermal energy, to be consumed locally, depending on needs and infrastructure. In some cases, platforms can be converted to battery charging stations. With respect to critical minerals, preliminary results have identified offshore producing fields with a potentially commercial concentration of critical minerals in the produced brine / reservoir fluids. Further study is being conducted to define the type and concentration of critical minerals, and to recommend the ideal production method for each high-ranking prospect.

Novel Information

Certain offshore reservoirs have the potential to coproduce geothermal energy and reservoir fluids. Further, there are locations in offshore basins that may have commercially producible levels of critical minerals. Novel methods of producing and concentrating brine will be necessary offshore to work within the constraints of the locally generated energy, and to preserve and protect the environment.
Models for Calculating Corrosion Rates in Water-Saturated and Under Saturated CO2 Systems & Water Solubility in CO2 Systems at Supercritical Conditions
Authors: Kowta Rama , Erickson Dale Douglas , Barker Richard , Neville Anne , Hua Yong
Published: April 2022

In water-containing dense phase CO2 environments, which are typical conditions seen in Carbon Capture and Storage (CCS) systems, corrosion rate increases in conjunction with humidity, typically reaching a critical humidity, beyond which corrosion rates become particularly high. In this work, we discuss the development of a model to calculate corrosion rates in CO2 systems, both pure as well as those containing impurities, with under-saturated water content at dense and supercritical conditions.

A new model is developed to predict corrosion rates in CO2 systems, both in presence and absence of impurities, with under-saturated water content at supercritical conditions while existing in-house models are used to predict corrosion rates at saturated water content. The model to calculate corrosion rates at under-saturated water conditions uses the solubility of water in CO2 rich phase at saturated conditions. A Peng-Robinson equation of state, E-PPR78, available in literature, is modified further to match water solubility in CO2 rich phase in the presence and absence of impurities at supercritical conditions and on both sides of the two phase-region.

We present results from the modified E-PPR78 model, validating calculated water solubility in the CO2 rich phase against experimental data available in literature for pure CO2 as well as for CO2 systems with impurities. The results presented cover a wide range of pressures and temperatures both in sub-critical and supercritical regions. For pure CO2 with water system, the error in the calculated water solubility in CO2 rich phase is less than 4% in sub-critical region and is less than 7% in the super-critical region. The presence of impurities in the CO2 stream influences the solubility of water and hence, the humidity and corrosivity of the CO2 stream. We present calculated water solubility of water in CO2 rich phase in CO2 and N2 mixture for different N2 concentrations and validate it against experimental data found in literature.

An empirical correlation was developed based on experimental data to predict corrosion rates in CO2 systems at under-saturated water conditions in the presence of impurities. The empirical correlation to calculate corrosion rate at water under-saturated conditions uses corrosion rate at water-saturated conditions, calculated from an in-house tool, and the water solubility in CO2 rich phase, calculated from modified E-PPR78 equation of state model.
Taking Subsea Operations to the Next Level by Applying Machine Vision to Perform Autonomous Inspections
Authors: Johansen Kristoffer
Published: April 2022

DeepOcean and partners have for multiple years been developing an Autonomous Inspection Drone (AID). This is a remotely operated vehicle designed to perform high-quality inspections of subsea assets. The AID is equipped with a state-of-the-art machine vision camera, which is used to autonomously navigate through a pre-programmed inspection scope. The operation of the AID is supervised by our remote operation center in Haugesund, Norway. This paper presents results from our first field trial.

A digital twin was constructed for multiple subsea templates. The digital twin was developed into a game where a model of the AID was controlled. This allowed inspection engineers to plan the route for the inspection. The planned route in the digital twin was exported to the AID. The AID autonomously executed the planned route. Autonomous navigation was made possible by combining an inertial navigation system, a USBL positioning system and a machine vision camera. The machine vision camera detected QR-codes on the subsea asset. This allowed the AID to correct position and determine the true location on the asset.

Multiple tests were performed during this field trial. Observations of these tests are presented in the paper. Examples of tests that were performed during the field trials include autonomous undocking and docking from TMS, executing of pre-programmed inspection route and station keeping when QR codes were detected on the subsea asset. It was observed in the field trials that the control system to the AID would need to be further developed. This is to increase the robustness and enhance the efficiency of autonomous navigation. These considerations are discussed in the paper, and conclusions are drawn with regard to how this may be achieved.

This paper will explain how DeepOcean planned and executed an inspection scope by combining a digital twin of the asset and a machine vision camera used to assist the navigation of the AID. The results and conclusions presented from this field trial are essential for the petroleum industry to step into a future where resident vehicles are able to perform value-creating work autonomously. In the near term, this work is forming the foundation for DeepOcean to increase the performance of simultaneous operations from our vessels. This will be made possible as the AID may be launched from the vessel, which is completing some other intervention work, and come back after the autonomous inspection has been completed. The operation may be supervised by our control centre in Haugesund, Norway