bluuebunny/crossref_metadata_2025_split huggingface dataset:
First Application in Oman of New Single Stage Retarded Sandstone Matrix Acidizing
Authors: Qassabi Hajir , Rafliansyah Andika Putra , Falla Johnny , Al-Yaaribi Ahmed , Al-Ruzeiqi Saleh 
Published: March 2023

Abstract
The objective of matrix acidizing in sandstone reservoirs using acid systems that contains Hydrofluoric acid (HF) is to widen the pore throats and spaces in order to increase the permeability around the wellbore and remove formation damage. One major disadvantage of this acid system is the secondary and tertiary reactions, which may lead to precipitations that damage the formation. Because of this, pumping sufficient pre-flush and post-flush volumes of Hydrochloric acid (HCl) is critical to prevent such damaging reactions. However, the placement of such fluids still is a concern in multiple opened layers or long open intervals zones.
Stimulating sandstone reservoirs in the Southern fields of the Sultanate of Oman is very challenging, especially in those that exhibit relatively low permeability. These formations, based on petrology work, contains significant amounts of clays and feldspars, which make it difficult in the designing process of the acid formulation. A new version of HF acid system was recently developed. It is specially formulated, so it does not require the addition of Hydrochloric acid (HCl) pre-flush. Because of this, it can be pumped as a Single Stage Retarded Acid System. In addition, its higher reactivity allows deeper penetration, and it has the ability to minimize secondary reactions and damaging precipitates.
Lab testing work was conducted to ensure the effectiveness of this Single Stage Retarded Acid System. The results were promising as they show a good improvement in the rock permeability. These results were encouraging to carry field trials in the sandstone reservoirs in Oman Southern fields. Up to now, it has been pumped in sandstones for oil producer wells and for water injector wells. The actual treatment using this system showed increased oil productivity by higher than 60% as well it shows higher than 80% in water injectivity.
This paper presents the testing, designing and pumping the SSRAS (Single Stage Retarded Acid System), as well as the comparison with the conventional HF acid system in Southern fields of Oman. It outlines the laboratory work and analysis done as well as the field trials.
Downhole Estimation of Relative Permeability using Dynamic Formation Testers: A Novel Approach to Reduce the Uncertainty in Reservoir Modelling Study
Authors: Kumar Saket , Joshi Parth , Bajpai Prakash , Aggarwal Akshay 
Published: March 2023

Abstract
The reservoir fluid flow is characterized by relative permeability data, whose measurements are conventionally made in the laboratory on the cores acquired downhole of different rock types. The major drawback of such conventional core (SCAL) studies is their inability to capture the native wettability and in-situ reservoir fluid flow characteristics. Moreover, this lab based relative permeability data is sometimes unavailable, which requires one to estimate the relative permeability curves based on understanding of the reservoir or public literature and further tune the curves to match the actual pressure and production history of the reservoir during dynamic modelling. This process also incurs additional cost and requires additional time and efforts. Hence, an attempt has been made in this study to develop a novel workflow to estimate the relative permeability curves downhole using formation testers. This new method for interpreting relative permeability curves will complement the already existing conventional methods like SCAL and can also be used directly in the absences of lab data.
In this approach, the Single Probe (PS), Pump Out (PO), and Fluid Analyzer (FA) modules of the Modular Formation Dynamic Tester (MDT) tool were assembled and set at the desired depth. Subsequently, the PO module was used to draw out the fluids from the formation and aid in recording the production and pressure drawdown data. The relative permeability of both oil and water phases were estimated at endpoint saturation using steady state approach, and the JBN method was applied after breakthrough and during transition phase using the displacement data (production and pressure data). The advanced well logs were used to interpret the other reservoir properties like porosity, permeability, and etc.
An Analytical Model for Pressure Transient Behavior of Acid-Fractured Well in Fracture-Cave Oil Reservoir: A Field Example from Tarim Basin in China
Authors: Ai Shuang , Pang Wei , Du Juan , Liu Mike , Tabish Haider Syed 
Published: March 2023

Abstract
In fracture-cavity carbonate reservoirs, caves and fractures are the basic storage space. The SN oil and gas field in the Tarim Basin is one of this special fracture-cave oil reservoir. The main storage and seepage space are large caves and large fractures, and the pore space is large, which can reach above the meter level. It is very difficult to interpret this kind of oil reservoirs by the conventional triple medium well testing method. It is of practical significance to establish a well testing interpretation model for cave-type reservoirs and to interpret the well testing data of such reservoirs. Based on the typical well-fracture-cave configuration, we consider the finite conductivity of acid fracturing fractures. The fracture zone is regarded as a linear formation with finite conductivity and volume. Due to cavity characteristics of the cave, it is regarded as an equipotential media, and the internal pressure is equal in the all volume, and the cave supplies fluid to the outside in the form of storage flow. By coupling the acid-fracture flow, the flow in the fracture zone and the cave flow, two mathematical models for well test of acid fracturing in carbonate reservoirs are set up. Practical solutions of bottomhole pressure are obtained by using Laplace transform and Stehfest numerical inversion algorithm. The research results show that there are six or seven flow regimes exhibited: acid-fracture linear flow, with or without fracture zone storage flow, linear flow in fracture zone, cave storage flow, linear flow in fracture zone, cave storage flow, boundary flow. The distance between the acid-fracture and the cave affects the duration of the linear flow in the fracture zone. The greater the conductivity of the fractured zone, the more the linear flow of the fracture, the smaller the conductivity, the greater the seepage resistance, and the linear flow is converted into the reservoir flow of the fracture. Finally, a field example was explained by using the double logarithmic curve chart of the drilled cave model, and several parameters including acid-fracture, cave and the fractured zone were obtained by inversion. The production simulated based on the inversion results are in good agreement with the actual values. This paper presents two practical models to interpret the transient pressure responses of acid-fractured well in fracture-cave reservoir. The flow behavior is firstly investigated and the field example demonstrated practical use of the model to obtain the key parameters of acid-fracture, fracture zone and the cave.
Preparation and Properties Investigation on Sand-Polyacrylamide Composites with Engineered Interfaces for Water Shutoff Applications
Authors: Almohsin Ayman , Krishnan Mohan Raj , Alsharaeh Edreese , Harbi Bader 
Published: March 2023

Abstract
Herein, we report a facile preparation and characterization of polyacrylamide (PAM)-2D nanofiller (commercial graphene (CG) and hexagonal boron nitride nanosheets (h-BN)) composite hydrogel coated sand for water shutoff application. To prepare the sample, 4 wt% of aqueous PAM solution that is mixed with organic cross-linkers of hydroquinone (HQ) and hexamethylenetetramine (HMT) in 1:1 weight ratio, aqueous potassium chloride (KCl) solution and a specific amount of CG or h-BN. A specific amount of the above solution is added to sand and well mixed and subsequently cured at 150 °C for 8 hours. The prepared sand-polymer composites were characterized by Fourier-transform infrared spectroscopy (FT-IR) for chemical composition, X-ray diffraction (XRD) for successful polymer coating onto the sand, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) for thermal stabilities. the success of the sand coating was evaluated based on the peak intensities depicted for the sand-PAM gels with respect to neat-sand and neat-PAM. The absence of some of the peaks and their corresponding decrease in the intensities indicates the successful coating of the PAM hydrogel matrix onto the sand surface. The thermal stability of the sand samples has reached as high as 190.7 °C. The prepared material has a high potential for water shutoff applications.
Well Productivity Optimisation with Tailored Hole Spacing in Smart Liners
Authors: Mogensen Kristian 
Published: March 2023

Abstract
Optimum productivity from long horizontal wells requires effective stimulation. The Smart Liner lower completion addresses shortcomings of other matrix-acid stimulation techniques in regards to acid placement along the reservoir section. The concept relies on a limited number of small holes (orifices) drilled through the liner itself to distribute acid over the entire drain length. Different hole spacings can yield similar flow distributions but may result in different stimulation efficiencies. What is best, a few deep wormholes with acid washing in between, or many, less penetrating but closer wormholes? The objective of this work is to investigate which parameters influence the optimum hole spacing leading to the most improved overall reservoir contact.
We derive a radial wormhole growth model as a function of time and initial jet velocity, which honors the observation that incremental penetration depth tapers off versus time. This model is specifically tailored to account for the substantial jet velocities generated by the limited-entry liner completion, often in the range of 15-50 m/s, occasionally higher. It qualitatively matches field observations showing that the maximum required acid coverage often lies in the range 0.4-0.5 bbl/ft. Exceptions to this trend have been observed and they deserve further investigation. The hole spacing generally increases with well length to ensure sufficient jetting towards the toe of the well.
Work is ongoing to convert the number and length of all wormholes combined to an average overall injectivity improvement for the well. This effort will lead to a more qualitative match to the real-time stimulation data. Field data suggest that the typical transient injectivity is improved by a factor 2-3, sometimes more, if the initial skin prior to stimulation is very high. Larger improvements have been observed during stimulation of dolomite rocks with 28 wt% HCl, possibly due to more drilling-induced damage.
Innovative Approach to Identify PVT Regions in a Sandstone Reservoir in Khafji Field with Geological Events
Authors: Al-Qenae Khaled , Al-Otaibi Mohammed , Belazreg Lazreg , Akhtar Mohammad 
Published: March 2023

Abstract
Prior to initiating a reservoir simulation study, the readiness of a complete set of fluid analysis data should be assured and quality checked. This usually includes, but not limited to, identification of any vertical and lateral variation of reservoir fluid properties. Identification of these trends can have tremendous impact on the results of the reservoir simulation project.
Recently, a reservoir simulation study was conducted on a brown reservoir in a Middle Eastern field. This reservoir is geologically characterized by various faults which were developed after fluid migration. The presence of these faults has resulted in communicated reservoir compartments. Application of traditional workflow in analyzing the PVT data was insufficient to identify any trend in the fluid properties or account for any vertical and lateral differences in reservoir fluid properties.
This paper explains the work done to characterize fluid properties for a structurally complex sandstone reservoir, where most of the downhole fluid samples were collected in the 1960s. Unfortunately, the sampling depth was not reported for most of the samples at that time, with no production logging data available to identify the production zones within the large perforation interval. Laboratory measurements indicate under-saturated oil with variation that could be correlated with depth. Samples were obtained from three geological subzones; Layers-1, 2 and 3, where a shale layer is believed to be partially separating Layer 1 from the other layers. Part of the challenge is that a large number of samples were collected from different sublayers as a combination, which increases sampling depth uncertainty.
Defining properties trend versus depth was the main challenge in the study. This uncertainty was addressed by developing an iterative "what-if?" analysis scenarios by integrating geological parameters. A new model was prepared that considered the initial conditions of the reservoir fluid before any migration or tectonic activities took place. Applying the proposed approach, resulted in a clear trend of hydrocarbon properties variation with depth and provided a clear observation of the presence of one PVT region in the reservoir. Based on the results of this study, one PVT region with a solution gas-oil ratio trend versus depth was applied into the reservoir model, which resulted in a reliable dynamic simulation model.
Assessing Geological Deformation Using Distributed Fiber Optic Sensing
Authors: Busetti Seth , Kazei Vladimir , Merry Harold 
Published: March 2023

Abstract
This work presents a conceptual framework for assessing geological deformation using distributed fiber optic sensing that is applicable to several common sources of strain encountered during the reservoir lifecycle. Common applications include strain associated with seismic and aseismic fault motion, natural and hydraulic fracture dilation and closure, as well as poro-elastic strain evolution during injection and production. We briefly review the main fiber-based techniques for recording geological sources of strain and highlight key deformation characteristics at different spatial and temporal resolutions. The relationships between common acquisition parameters such as spatial resolution, data sampling rate, ability to measure relative and absolute strain, and a priori knowledge of geological strain including the availability of baseline measurements are discussed. A few examples are shown from experimental studies at the Houston Aramco Research Center. Using these insights as a conceptual framework for assessing geological deformation leads to more informed decisions when planning distributed fiber optic sensing acquisitions and interpreting associated strain data.
New Horizon for Downhole Scale Management Towards Sustained Well Production
Authors: Almajid Hussain , Thwaiqib Ibrahim , Ribeiro Carlos , Alghamdi Khuloud 
Published: March 2023

Abstract
Iron sulfide scales is considered one of the most commonly encountered formation scale in the oil and gas industry which can adversely impact well deliverability and integrity. Traditional chemical treatments using inorganic acids such as HCl are not favorable due to its corrosive nature and rapid generation of H2S gas. The success rate for such operation is further challenged by the molar ratio of iron to sulfur and the existing polymorph of iron sulfide such as pyrite, pyrrhotite, troilite, marcasite and mackinawite.
This paper aims to share the laboratory development and field application results for a revolutionary chemistry that was developed as an integrated solution to dissolute iron sulfide scales and inhibit further scale nucleation. Extensive laboratory testing was conducted under anaerobic conditions to create an evolved chelating agent with high iron sulfide dissolution, minimal corrosion rate and no H2S generation. The experimental setup included in-situ mixing of Fe(+2) and S(-2) to create iron sulfide scale that were placed in glass vial reactors and exposed to specific temperature and pressure. Furthermore, a thorough evaluation of sulfide scale properties and behavior under varying reservoir pressure and temperature is incorporated into a computational model to understand and accurately control the scale deposition process.
Several cleanout jobs have been successfully performed in the field using this treatment. Lab results showed minimal presence for the ferrous ion and total sulfide once filtered from the aqueous phase. Furthermore, the results for iron sulfide dissolution at different pH levels will be shared to determine the optimum pH values for the chelating agents. The collected data showed that this dissolver was able to outperform THPS based dissolvers without the adverse effects of HCl. Post job results will be discussed in this paper including job design, field execution, lessons learned and solid compositional analysis. Furthermore, inhibition program has been implemented based on the acquired results from this model and frequent inspection conducted showed no scale deposition over extended production periods.
The novelty of this approach is its ability to efficiently remove iron sulfide scales and inhibit nucleation at early stages without relying on inorganic acids. Lab results will be discussed in detail to examine the role of chelating agents in iron sulfide dissolution at different pH levels under anaerobic conditions. Field deployment data will be shared to definitively prove the effectiveness of this treatment in removing and preventing further iron sulfide precipitation. This study will help shed some light on an issue that has long concerned the oil & gas industry and up to this date no effective prevention mechanism has been discovered.
CO2 Mineral Trapping Potential of Carbonates: A Numerical Investigation
Authors: Mouallem Johny , Fathy Ahmed , Arif Muhammad , Mahmoud Mohamed 
Published: March 2023

Abstract
During CO2 geo-storage, mineral dissolution is considered as the safest trapping technique however it is the longest and the most complicated trapping mechanism involving geo-chemical reactions and physical forces like diffusion and advection. Many factors also influence the mineral trapping capacity of the geological formation e.g., mineralogy, temperature, pH, CO2 fugacity, pressure of CO2, salinity and composition of the brine.
The scope of this study is to investigate the mineral trapping of CO2 in Arabian carbonates reservoirs as a function of temperature, brine composition and pH of the subsurface systems. Numerical simulations are performed using the multi-phase simulator GEM-CMG. 2D and 3D models are developed to examine the mechanisms occurring during mineral trapping and how these affect its efficiency. The mineralogy of a carbonate field from an Arabian formation is used. Sensitivity analysis has been performed on the effect of temperature, pH and brine composition on CO2 mineralization tendency and porosity.
The results suggest that dissolution and precipitation of minerals occurred during and post CO2 injection while pH had the major influence on mineral trapping. At basic pH conditions, pH=9, the highest amount of CO2 was mineralized while at mid pH, precipitation of carbonates decreased remarkably. Changing the brine composition also highly affected the storage capacity e.g., divalent salt accelerated CO2 mineralization. Moreover, temperature tends to promote the mineral activity during CO2 storage.
While a score of publications investigated CO2 storage via structural, residual and dissolution trapping mechanisms, still the mineral trapping potential and its influencing factors have not been investigated much. This paper thus provides new insights into CO2 sequestration by mineral trapping pertinent to Arabian carbonate rocks.
Global First 18.625 and 13.375-in Level-2 Casing-While-Drilling Successful Deployment through Open-Hole and Cased-Hole Sidetracked Wellbores to Isolate Severe Unstable Zones
Authors: Almasmoom Salahaldeen S , Refai Ahmed , Al-Qahtani Faris A , Stonestreet David B 
Published: March 2023

Abstract
During non-productive time (NPT) such as stuck pipe incidents, reducing the operational time and associated cost of the trouble mitigation should always be the goal. Therefore, the engineering team searched for new and innovative ways to reduce the NPT when stuck pipe incidents happen, and successfully utilized an existing technology in a new way not yet performed on a global basis.
In seldom incidents drilling or tripping through unstable zones (especially when drilling through sticky shales and loose sandstone zones charged with downhole faults/fractures) with complete loss of circulation, severe tight spots, stalling tendencies, hard backreaming, etc. might be experienced. In the worst case, the pipe might get stuck and cannot be freed. The engineering team investigated several options to allow drilling and casing off the trouble zones in such incidents, while reducing the NPT in the same time. Sidetracking through open-hole and/or cased-hole whipstock, then utilizing level-2 casing-while-drilling technology to drill and case-off the instable zones was the best cost effectient option.
Successful deployment of level-2 16-in × 13-⅜-in casing-while-drilling (CwD) technology through an 18-⅝-in cased-hole sidetrack whipstock and level-2 22-in × 18-⅝-in CwD technology through open-hole sidetrack led to drilling and casing off severe unstable sections in two separate wells in different areas of interest. The level-2 13-⅜-in CwD utilization to drill and case-off trouble zones through cased-hole sidetrack was the global first. The level-2 18-⅝-in CwD utilization to drill and case-off trouble zones through open-hole sidetrack was the country first. Both led to significantly reducing the non-productive time (NPT) resulted from the stuck pipe incidents in a cost effective manner. Extensive engineering simulations, technical limits, and risks assessment were set to insure flawless execution. During the job execution, the drilling performances were constantly monitored. The engineering simulations are updated using the actual parameters to ensure accurate measurements of the accumulated fatigue while being rotated to preserve the casing due to exposure to high dogleg severity (DLS) in the sidetracked wellbore. Furthermore, the hydraulics are optimized real-time to ensure hole cleaning without further increase in the equivalent circulating density.
Even with no prior global experience of the utilization of this technology through such operation, the pursuit of the technical limit was to reduce the NPT as much as possible. The technical paper will highlight the planning steps, challenges, detailed engineering simulation, risks mitigations and engineered solutions, and the successful results of the deployment of level-2 CwD runs through sidetracked wellbores.