bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Simulation and Pilot Application of Low Salinity Water Flooding for Offshore Low Permeability Reservoir
Authors: Shi Hongfu , Liu Yingxian , He Yifan , Xu Wankun 
Published: March 2021

Abstract
The use of LSWF (Low Salinity Water Flooding) is becoming more prevalent in recent years which can both improve the recovery factor and reduce the cost compared to other EOR (enhanced oil recovery) technics. This is especially important for the offshore oilfield development at present. Moreover, good quality of injected water is more applicable to low permeability sand which is characterized as smaller pore-throat radius and is easier damaged. Therefore, LSWF technology is proposed to address the above production problem while reduce the investment of equipment upgrade.
In this paper, we presented the optimization and implementation of LSWF for offshore low permeability reservoir. Firstly, we provided a critical review of LSWF included the main mechanisms, laboratory test and field effect. Secondly, we designed and conducted several laboratory core flood tests. Thirdly, a lot of synthetic models were established to simulate the effects of LSWF and to optimize the field program. Finally, the production performance of the pilot wells was discussed.
After LSWF, the water injection well presents the phenomenon of "scissors" - the injection pressure drops significantly below the safety pressure while the injection volume increases. Moreover, the decline of pilot well groups decreased by 20% ~ 26% compared with non-water flooded. The estimated recovery factor increased by 12%, which is consistent with other field tests worldwide. In summary, LSWF is a feasible, neconomic and efficient method for offshore low permeability reservoir production.
Near-Critical Reservoir Fluid Mixture Identification and Phase Behaviour
Authors: Ling Ru Piin , Hussain Mansoor , Razak Amin Nizar , Ashqar Ayham , Jamaludin Junirda , A Karim M Azan 
Published: March 2021

Abstract
To appraise hydrocarbon and its properties of a low permeability formation within deep Baram delta reservoirs. Formation X is low permeability silty sandstone. It forms along other formations stacked sandy shale reservoirs. The stacked formations are interpreted as Hydrocabon bearing formations based on the openhole and pressure data. However, the reservoir in question, showed features different from the adjacent reservoirs. This manuscript appraises the reservoir and illustrates the workflow followed to identify its fluid type and the best method to produce the hydrocarbon.
Triple combo logs identified formation X as hydrocarbon bearing with low permeability and low porosity. Formation pressures gradients indicated the formation to be oil; however, the bottom hole sample, when pumped out, indicated alternating of oil and gas despite the low differential pressure.
During the PVT measurement the sample was first re-pressurised until a single phase was achieved and it was then subjected to Differential Liberation and Constant Composition Experiments (CCE). These experiments showed the Bubble Point pressure of the sample to be higher than the reservoir pressure, thereby indicating two mobile phases in the reservoir and the probability of a Gas-Oil Contact (GOC). The Experiments were also successfully simulated and matched using the Peng Robinson Equation of State. The Laboratory experiments directly contradicted the interpretation of Wireline Logs and pressure gradient both of which, indicated single phase light oil.
The collected bottom hole sample indicated that both oil and gas are mobile at reservoir level, this finding is supported by PVT laboratory experiments. The Differential Liberation, CCE experiments and EOS fitting demonstrated the fluid to be two Phases at Reservoir Condition where both phases are likely to be mobile. Therefore, it is suspected that the fluid will go from being Gas to Oil with increasing depth without going through GOC, i.e. with continuous compositional grading as is possible for fluids near their critical temperature. This phenomenon could not be captured using open hole conventional logs and therefore the is team is currently investigating the best practice to identify such reservoirs.
Study on Boundary of Control Models and Mechanisms of Acid Rock Reaction in Carbonate Reservoirs with Different Dolomite Mass Fraction
Authors: Yan Jun , Cui Mingyue , He Anle , Qi Ning , Cui Weixiang , Wen Xiaohong 
Published: March 2021

AbstractThe understanding of acid rock reaction kinetics is the basis for the proposal of carbonate rock acidizing and acid fracturing. So far, the study of acid rock reaction kinetics in carbonate reservoirs is mostly focused on limestone reservoirs. The difference in acid rock reaction characteristics between limestone and dolomite reservoirs is obvious. In order to clarify the boundaries of control models and mechanisms of acid rock reaction in dolomite reservoirs, to guide the optimization of acidizing and acid fracturing proposal for carbonate reservoirs with different dolomite contents.The experimental study of acid rock reaction kinetics was completed with carbonate cores with different dolomite mass fraction, and the difference of acid corrosion mechanism between limestone and dolomite was analyzed by scanning electron microscope.The dolomite acid rock reaction kinetics equation under the control of different factors was established, and it was clarified that the temperature 90°C and the rotation speed 500r/min are the boundary of the surface reaction and mass transfer control mode. The study found that under the same experimental conditions, the acid rock reaction rate of dolomite is much lower than that of limestone; as the dolomite mass fraction increases, the acid rock reaction rate decreases rapidly, when the dolomite content exceeds 75%, the reaction rate of acid rock is reduced to the lowest and tends to be stable. Limestone is dominated by surface dissolution, with good dissolution effect, fast dissolution rate; dolomite is dominated by point dissolution, with holes on the surface, poor dissolution effect and low dissolution rate. Compared with limestone, the particle size of dolomite crystal is much larger, and the specific surface area is small, which is also the reaction rate of acid rock in dolomite is slower than limestone, this is also a main reason why the reaction rate of dolomite acid rocks is slower than that of limestone. So the acidizing or acid fracturing methodology of the dolomite reservoir is different from that of the limestone reservoir. The acid rock reaction rate and hydrochloric acid concentration should be appropriately increased within the allowable range to improve the uneven etching of the fracture wall, thereby increasing increase the conductivity of acid fracture.
Utilizing Pseudo Well Connections to Simulate Multi-Stage Hydraulic Fracturing - Example Based On the Study of a Tight Gas Asset
Authors: Lokhandwala Aamir , Joshi Vaibhav , Dutt Ankit 
Published: March 2021

Abstract
Hydraulic fracturing is a widespread well stimulation treatment in the oil and gas industry. It is particularly prevalent in shale gas fields, where virtually all production can be attributed to the practice of fracturing. It is also used in the context of tight oil and gas reservoirs, for example in deep-water scenarios where the cost of drilling and completion is very high; well productivity, which is dictated by hydraulic fractures, is vital.
The correct modeling in reservoir simulation can be critical in such settings because hydraulic fracturing can dramatically change the flow dynamics of a reservoir. What presents a challenge in flow simulation due to hydraulic fractures is that they introduce effects that operate on a different length and time scale than the usual dynamics of a reservoir. Capturing these effects and utilizing them to advantage can be critical for any operator in context of a field development plan for any unconventional or tight field.
This paper focuses on a study that was undertaken to compare different methods of simulating hydraulic fractures to formulate a field development plan for a tight gas field. To maintaing the confidentiality of data and to showcase only the technical aspect of the workflow, we will refer to the asset as Field A in subsequent sections of this paper. Field A is a low permeability (0.01md-0.1md), tight (8% to 12% porosity) gas-condensate (API ~51deg and CGR~65 stb/mmscf) reservoir at ~3000m depth. Being structurally complex, it has a large number of erosional features and pinch-outs.
The study involved comparing analytical fracture modeling, explicit modeling using local grid refinements, tartan gridding, pseudo-well connection approach and full-field unconventional fracture modeling. The result of the study was to use, for the first time for Field A, a system of generating pseudo well connections to simulate hydraulic fractures. The approach was found to be efficient both terms of replicating field data for a 10 year period while drastically reducing simulation runtime for the subsequent 10 year-period too. It helped the subsurface team to test multiple scenarios in a limited time-frame leading to improved project management.
A Novel Approach to Successfully Cement the Long Horizontal Liners Across Khuff-C Reservoir in High-Pressure Gas Producer Land Wells: A Case History from Saudi Arabia
Authors: Ali Wajid , Mata Freddy Jose , Al-Turki Faisal Abdullah 
Published: March 2021

Abstract
Maintaining zonal isolation is vital to well economics and productive life. Well integrity is becoming more challenging with the drilling of deeper, highly deviated, and horizontal wells worldwide. Oil companies are focused on to enhance the well productivity during drilling long horizontal wells in a harsh environment by achieving maximum accessible reservoir contact. These wellbore geometries incorporate additional challenges to design and deliver a dependable barrier. In this paper, a case study about cementing the longest liner across Khuff-C reservoir has been presented discussing the main challenges, engineering considerations, field implementation, results, and conclusions.
The well was drilled horizontally across Khuff-C carbonates using oil-based drilling fluid. The 5-7/8-in open hole section was planned to be cemented in single stage, utilizing 8370 ft of a 4-1/2-in liner. Careful attention was paid to estimate the bottom hole circulating temperature, using the temperature modeling simulator. A 118-lbm/ft3 slurry was designed to keep the equivalent circulation density intact. Gas migration control additives were included in the slurry design to lower the slurry's transition time, in order to reduce the chances of gas migration through the cement slurry. The slurry was batch-mixed to ensure the homogeneity of the final slurry mixture. A reactive spacer was designed to improve the cement bonding from long term zonal isolation perspective. Additionally, the spacer was loaded with optimum amounts of surfactant package to serve as an aid to remove the mud and to water-wet the formation and pipe for better cement bonding. Centralizers placement plan was optimized to allow around 63% average standoff around the pipe, staying within the torque and drag (T&D) limits. The cement treatment was performed as designed and met all zonal isolation objectives.
The process of cementing horizontal liners comes with unique procedures. There are several challenges associated with carrying out wellbore zonal isolation for primary cementing of horizontal liners, therefore, a unique level of attention is required during the design and execution stages. The slurry design requires careful formulation to achieve the desired specifications while ensuring its easy deployment and placement in the liner annulus. By planning in advance and following proven techniques, many of the problems associated with the running and cementing of deep and long horizontal liners can be alleviated.
This paper highlights the necessary laboratory testing, field execution procedures, and treatment evaluation methods so that this technique can be a key resource for such operations in the future. The paper describes the process used to design the liner cement job and how its application was significant to the success of the job.
Reducing Uncertainties to Shape the Future of Exploration
Authors: van Mastrigt Pieter , Quinn Michael J. 
Published: March 2021

Abstract
For any given Exploration oil and gas portfolio and associated opportunities, successful business decisions can only be made on the basis of technically robust estimates of the subsurface risk versus the resource potential and estimate of the associated upside(s). Ideally, these estimates should incorporate the entire spectrum of opportunities for the complete portfolio and they should be made in a consistent and comparable way. However, as Explorers, we are often faced with data that is incomplete, limited, of variable quality, and/or inconsistent. As a result, subsurface evaluation may be seen more as educated guessing rather than a robust science of evaluation grounded in facts and defensible logic. In their January 2020 paper "Randomness, serendipity, and luck in petroleum exploration" authors Milkov and Navidi (Ref 1.) go quite a bit further and demonstrate that luck is a significant factor in the exploration success equation. They also showed a general lack in long-term consistency in exploration results of individual companies. Indeed, after we looked at PETRONAS’ own historical POSg versus actual technical success rates and observed only a fair to poor relation between actual technical success rate and the pre-drill POSg estimate. A similar—albeit less worrisome—observation was made for volume ranges and fluid phase predictions. Clearly, there is, and always has been, a phenomenal challenge for the Petroleum Geoscientists to provide the sought after estimates as accurately as possible, and we were no exception.
In a bid to improve on this PETRONAS set out on a more disciplined approach to characterizing subsurface uncertainties on its conventional exploration efforts. Over time, more accurate characterizations of such exploration risk and resource potential have followed from a series of procedural guidelines, enhanced capability training program and careful governance of exploration workflows. With improved capabilities and workflow consistency, our evaluation teams have delivered substantially better subsurface evaluations. This in turn has led to more confident decision-making on e.g., individual drilling decisions and new play entries. While our newly implemented workflows are not groundbreaking in isolation, in combination they have delivered notable success and an improved ability to shape the future growth for PETRONAS. In this article, we will highlight the main contributing changes and demonstrate that the overall improvements are indeed impactful. We are not directly challenging the article of Milkov et. al., but are convinced that professionalism and scientific discipline is the deciding factor in the Exploration success equation.
Controlling Costs and NPT: An Economical Approach to Wellbore Strengthening Offshore Vietnam
Authors: Nanda Kumar Kishen , Moroni Luigi , Kongto Abhijart , Tran Thanh Bao , Nguyen Hoang Nghia , Tran Tuan Lam , Do Ngoc Chau 
Published: March 2021

Abstract
There are many challenges while drilling highly inclined and depleted formations offshore Vietnam that result in various wellbore stability issues such as severe losses, stuck pipe, cavings, tight-hole and pack-offs. These issues may be independent of mud type and can occur when drilling with both oil/synthetic-based and water-based muds. These depleted sections typically consist of sandstones interbedded with claystone & siltstones. Traditionally, the wellbore strengthening fluids solution applied to drill through these sections with synthetic and water-based mud in Vietnam faced limited success.
Wellbore strengthening (WBS) is a proven and effective solution especially for narrow-drilling margin and depleted formations. The basic concept of WBS relies on the creation and simultaneous plugging of small fractures with appropriate WBS material. The resulting elevated stress around the wellbore strengthens the borehole by creating an increased hoop stress that leads to an increase in near wellbore stresses. Proprietary modelling software can be used to calculate the pressure induced fracture apertures for wellbore strengthening applications and determine the optimum particle size range to bridge these fractures, allowing fluids to be designed to minimise wellbore instability.
This design process was used to optimize material additives to effectively bridge fractures, for wellbore strengthening, and pore throat openings in porous/permeable formations for the prevention of seepage losses and differential sticking. A review of the application procedure identified the optimum method to apply the wellbore strengthening material which would minimise product consumption and reduce well costs. After extensive modelling simulations and testing, this fluid design was applied to drill two challenging wells in Vietnam.
This paper presents the process of modelling, based on formation geo-mechanics information, customization and laboratory testing of the fluids design coupled with a successful and economical method of application in the field. Application of this process enabled the operator to drill through the depleted challenging sections with a maximum overbalance pressure of 3,200 psi, conduct logging and coring runs and complete the well at a lower cost and with zero fluids related non-productive time compared to previous wells.
A Success of Modified Water Based Mud as Drilling Fluid Optimization to Drill Shale Formation at South-S Wells
Authors: Hadinata Dwie , Mulia Yuliawan , Rudyanto Theodore , Laharan Adi , Haurissa Poultje , Soemantri Hedriawan , Subroto Borman , Suradilaga Rangga , Sugianto Rudi 
Published: March 2021

AbstractThis paper is to explain the optimization of using Modified Shale Inhibitor Water Based Mud (WBM) to drill up to 5,500 ft interval of K-formation reactive shale on South-S Gas Wells.By combining a comprehensive method consists of drilling fluid laboratory test and lessons learned in S area, the optimization was done by determining the amount or concentration of Polyamine & KCl combination, pure Polyamine, Polyamine & NaCl combination, and Pure KCl-Polymer in WBM system as a shale inhibitor. The comparison of shale inhibitor compositions were made by comparing the achieved optimization of drilling fluid program such as drilling time, cost economic, and environment aspect.The basic idea of the WBM optimization was to improve drilling time during drill 5,000 ft footage in 12-1/4" hole section in reactive shale formation as per drilling program. Laboratory test consists of Linear swelling meter with various parameter concentration of Polyamine & KCl combination, pure Polyamine, Polyamine & NACl combination, and Pure KCl-Polymer in WBM system as a shale inhibitor and cation exchange capacity test (CEC or MBT) was done using composite of offset well shale cutting. Experience showed that on 12-1/4" hole section, while facing reactive shale (CEC 18 - 24 meq/100 gr) from K-formation on South-S, modified WBM was proven to eliminate reactive shale issues and lead to budget saving without environmental issues.
Improving the Stratigraphic Concept of Channel Complex Reservoir of a Brown Field: A Case Study in Field A
Authors: Dzulkifli Izyan Nadirah , M. Yusoff Amy Mawarni , Basri Abdul Hakim , Jamaludin Izzuddin , M. Som M. Rapi , M. Akram M. Faizal , M. Diah M. Amri 
Published: March 2021

Abstract
Major reservoirs in Field A namely A-2, A-3U, A-3M, and A-3L, are deposited within a multi stacked channel complex system within Group I in Malay Basin. These reservoirs were previously understood based on existing data to have no or very minimal vertical communication between them and are treated as separate systems.
In 2018, three wells were proposed to drain the attic oil in the north region of A-3U reservoir. When drilling these infill wells, it was discovered that the pressure has exceeded initial reservoir pressure although the reservoir has been idle for almost a year prior to the drilling. The results of the multi-rate test of two of the three infill wells that are less than 1 km apart are significantly different from one another. Post drilling, more tests were executed to investigate the connection between the sand. Studies were also done by incorporating the static and dynamic reservoir modeling data.
Based on the result of the tests and studies, it was concluded that all of the major sands are connected at some areas. This new finding on the connectivity might be able to explain the additional volume needed to history match some of the reservoirs.
Establishing stratigraphy concepts of a reservoir particularly in a channel complex system is an ongoing process, in this case, a brown field of almost 20 years of production. All data including new well data and dynamic data plays a vital role for a better understanding of the reservoir. It is essential to incorporate the updated geological understanding into the static model to have a representative simulation for better history matching and prediction. Moving forward, instead of building a separate grid model for each reservoir, a larger framework consist of intercalated reservoir grids will be built with this new geological understanding for dynamic simulation.
Handling High-Intensity Brine Influxes Using Flow-While-Drilling FWD Techniques in a Salt Formation in Chinarevskoye Field
Authors: Aidoo Ato , Zenzin Valeriy , Kropochev Yuriy , Akulov Konstantin , Vitvitckii Evgenii , Arystan Abylaikhan , Juchiac Emil , Palten Peter-Joern , Amanbayev Yerlan , Higginson Tim , Amangeldiyeva Diana , Aliyeva Aida 
Published: March 2021

Abstract
This case study describes the approach taken when drilling an 11 5/8-in. hole section through a salt formation on the Chinarevskoye field in the West Kazakhstan Oblast region where high-intensity brine influxes and subsequent flow had been encountered. The intensity of the brine flow, when encountered, had ranged from 5,000 to 6,000 L/min at an equivalent kick density of 2.2 SG, and it is believed to be among the most intense brine flow experienced in the world during drilling operations.
Standard well control measures proved to be inefficient because of the narrow margin between pore pressure and fracture pressure gradients. Several techniques were applied to combat such influxes in a safe manner with minimum associated nonproductive time (NPT). The high-pressured formation in this hole section is associated not only with brine influxes, but also with losses and gas increase scenarios. As a result, the company adopted unconventional drilling techniques with a combination of planned flow-while-drilling (FWD) and mud-cap drilling techniques to reach total depth (TD).
These two techniques created a viable and cost-effective solution to mitigate such challenges, helped the company to drill to the planned section TD, and consequently complete the well within the defined authorization for expenditure (AFE) without associated NPT. The paper will cover and emphasize techniques, along with details on running casing and cementing the hole section, which required an unconventional approach for success. The paper will also briefly outline the equipment used, such as rotating control devices (RCDs), a choke manifold, and a separator when drilling this section and their limitations. Despite the complications, the well was successfully drilled, and this experience provided an opportunity for learning.
The marked improvements in well control, loss management, and cementation displayed that combining knowledge and experience can reduce the negative impact on well costs when drilling similar cases.