The SPE has split the former "Management & Information" technical discipline into two new technical discplines:
- Data Science & Engineering Analytics
The SPE has split the former "Management & Information" technical discipline into two new technical discplines:
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Abstract The deep carbonate reservoir formation on this field has proven to be an extreme High-temperature (HT) environment for downhole equipment. While drilling the 5000 - 6500 ft 5-7/8" slim long laterals across this formation, very high bottom-hole circulating temperatures is encountered (310-340 degF) which exceeds the operating limitation for the downhole drilling/formation evaluation tools. This resulted in multiple temperature-related failures, unplanned trips and long non-productive-time. It became necessary to provide solution to reduce the BHCT-related failures. Performed offset-wells-analysis to identify the BHT regime across the entire-field, create a heat-map and correlate/compare actual formation-temperatures with the formation-temperature-gradient provided by the operator (1.4-1.8 degF/100-ft). Drilling reports and MWD/LWD/wireline logs were reviewed/analyzed. Reviewed tools-spec-sheets, discovered most of the tools had a maximum-temperature-rating of 300-302 degF and were run outside-technical-limits. Observed temperature-related-failures were predominant in very long slim-laterals, which indicated that some of the heat was generated by high flow rate/RPM and solids in the system. Tried drilling with low-RPM/FR, did not achieve meaningful-temperature-reduction. After detailed risk-assessment and analysis on other contributing factors in the drilling process, opted to incorporate mud-chiller into the surface circulating-system to cool-down the mud going into the well. Upon implementation of the mud chiller system, observed up to 40 degF reduction in surface temperature (i.e. temperature-difference between the mud entering/leaving mud chiller). This was achieved because the unit was set-up to process at least twice the rate that was pumped downhole. Also observed reduction in the bottom-hole circulating temperature to below 300 degF, thus ensuring the drilling environment met the tool specifications. The temperature-related tools failure got eliminated. On some of the previous wells, wireline logging tools have been damaged due to high encountered downhole temperature as circulation was not possible prior-to or during logging operation. The implementation of the mud-chiller system has made it possible for innovative logging thru-bit logging application to be implemented. This allows circulation of cool mud across the entire open hole prior to deployment of tools to perform logging operation. This has made it possible for same logging tool to be used for multiple jobs without fear of tool electronic-components failure die to exposure to extreme temperatures. The long non-productive time due to temperature-related tool failures got eliminated. The numerous stuck pipes events due to hole deterioration resulting from multiple round trips also got eliminated. Overall drilling operations became more efficient. The paper will describe the drilling challenges, the systematic approach implemented to arrive at optimized solution. It will show how good understanding of drilling challenges and tailored-solutions delivers great gains. The authors will show how this system was used to provide a true step-change in performance in this challenging environment.
Elgaddafi, R. M. (Petroleum Engineering Department, Australian University, Kuwait City, Kuwait) | Al Saba, M. (Petroleum Engineering Department, Australian University, Kuwait City, Kuwait) | Almarshad, A. (Kuwait Institute for Scientific Research, Kuwait City, Kuwait) | Amadi, K. (Petroleum Engineering Department, Australian University, Kuwait City, Kuwait)
Abstract In meeting the world's climate-change goals, the oil and gas industry will have to play a significant part, although the specific initiatives chosen to reduce the emissions may vary, re-engineering waste products that contribute to carbon emission into useful recyclable products for the oil and gas industry can significantly contribute to developing a circular economy and sustainable environment. This study considered recycling finely ground auto-tire rubber as an effective drilling fluid additive. Waste tire, which is a major air pollutant when burned, was collected from a national recycling company. A laboratory study of using the finely ground auto-tire rubber waste as an effective fluid loss control and bridging additive was performed and compared with sized graphite, which is a commonly used bridging material in the industry. A commonly used water-based drilling fluid formulation was employed as a base fluid for all the experiments. The performance of the drilling fluid containing the waste auto-tire finely ground rubber was assessed by conducting standard rheological measurements and API fluid loss, where concentrations ranging between (0.0 – 10 lb/bbl) were added to the base fluid. The effect of adding the waste auto-tire rubber on plastic viscosity, yield point, apparent viscosity, and fluid loss was assessed. In addition, the possibility of replacing the sized graphite with the proposed material was investigated. The results showed a significant reduction in a fluid loss by up to 23% by the addition of (10 lb/bbl) of finely ground auto-tire rubber waste to the base fluid (containing 5% bentonite). Furthermore, analysis of the test measurements showed a minor to negligible effect on the rheological properties compared to the base fluid. Also, it revealed that waste auto-tire finely ground rubber can successfully functionalize as a fluid loss additive and completely replace sized graphite as a bridging material, where replacing the sized graphite with the proposed material resulted in a reduction in the fluid loss of up to 21%. The promising results obtained in this study highlight the huge potential for this initiative in utilizing recycled auto-tire waste materials as a possible drilling fluid additive and demonstrate a sustainable technique with large-scale application in the oil and gas field whilst reducing solid waste disposal and consequent CO2 emissions resulting from burning waste tires.
Perozo, N. (Institute of Subsurface Energy Systems, Clausthal University of Technology, Clausthal-Zellerfeld, Lower Saxony, Germany) | Amirhosseini, S. Fazel (Institute of Subsurface Energy Systems, Clausthal University of Technology, Clausthal-Zellerfeld, Lower Saxony, Germany) | Tavakoli, M. (Institut für Materialprüfung und Werkstofftechnik Dr. Neubert GmbH, Clausthal-Zellerfeld, Lower Saxony, Germany) | Holzmann, J. (Institute of Subsurface Energy Systems, Clausthal University of Technology, Clausthal-Zellerfeld, Lower Saxony, Germany) | Neubert, V. (Institut für Materialprüfung und Werkstofftechnik Dr. Neubert GmbH, Clausthal-Zellerfeld, Lower Saxony, Germany) | Jaeger, P. (Institute of Subsurface Energy Systems, Clausthal University of Technology, Clausthal-Zellerfeld, Lower Saxony, Germany)
Abstract The main objective of the presented work is to evaluate the effect of hydrogen service conditions on the mechanical properties of API steel grades used for well completions. The evaluation methodology implies a preconditioning of the steel specimens to long-term exposures under high-pressure hydrogen atmospheres and compare the results of subsequent mechanical tests with those of steels not being exposed to this gas. The aim of this research is to compare the performance of different API grades when subjected to hydrogen service. The outcomings of the study will help to evaluate long-term integrity of completion systems and materials compatibility for hydrogen storage applications. Mechanical tests like notched-tensile tests, hardness determination and impact tests were performed, in order to detect the embrittlement of the metals by comparing results between specimens not previously charged with hydrogen and specimens being subjected to a hydrogen atmosphere under high-pressure. The notch tensile specimens were pre-stressed to 80% of the nominal yield strength, in order to force and assure the hydrogen diffusion into the notch area where localized increased tensile stresses are concentrated. Furthermore, by means of carrier gas hot extraction analysis the hydrogen content in the samples was measured, to give an indication of the absorption capacity of these grades under the stated conditions. The API grades L80, P110 and Q125 have been selected to represent a wide and popular selection of ductility and yield strength. All samples were subjected to a series of mechanical tests to determine the presence of hydrogen embrittlement. The results show different behavior of the materials after being exposed to a hydrogen atmosphere, from the noticeable decrease to even a "no effect" on the mechanical properties. The results of notch tensile tests of the steels L80 and Q125 are showing some level of hydrogen embrittlement, compared to P110, being the one least affected by the presence of this gas. The measurement of hydrogen content in the samples delivers similar results for all the grades. Microscopic analysis shows the structure of the crystal lattice of the steels studied, helping to understand, together with the state of stress, how sensitive the material is to be affected by hydrogen embrittlement. There is no literature that describes the hydrogen effect on the mechanical properties of API steels used for tubings and casings in well completions, nor their sensitivity to hydrogen embrittlement. The results of this research are of great importance to give an idea of the compatibility of the steels that can be used for high-pressure hydrogen operations, such as hydrogen underground storage as well as to evaluate the potential recompletion or use of existing wells.
Wu, Xingru (The University of Oklahoma) | Dai, Lei (Southwest Petroleum University) | Chang, Qiuhao (The University of Oklahoma) | Qiuhao, Sadam (United Energy Pakistan Limited) | Shiau, Bor Jier (The University of Oklahoma)
Abstract Laboratory experiments have demonstrated that injecting urea solution as a CO2-generating agent into an oil reservoir may significantly enhance oil recovery. When the reservoir temperature is above 50°C, urea is hydrolyzed to carbon dioxide and ammonia. This technology overcomes many supercritical CO2 problems and can be very attractive for thousands of stripper wells that produce oil on marginal economic feasibility. However, previous efforts mainly focus on laboratory tests and mechanisms study. The actual field performance of this technology is likely dependent on reservoir heterogeneity, and its economic viability is expected to be closely related to its optimization. This highly relies on numerical modeling and simulation capability. The synergic mechanisms in in-situ CO2 EOR (ICE) using urea are complex. Firstly, the decomposition of urea injected leads to CO2 and ammonia under proper reservoir conditions. The generated CO2 in brine partitions preferably into the oil phase and decreases oil viscosity while swelling the oil effectively. The co-generated product, ammonia, can potentially reduce the interfacial tension (IFT) between the oil/water phase, which moves the relative permeability (or saturation) curves and position to offer additional oil production. In the first attempt, the dominant parameters, including urea reaction kinetics, the stoichiometry of the decomposition process, the oil swelling effect, and the impact of IFT reduction on the relative permeabilities, were considered and incorporated into the numerical modeling effort. We used the chosen numerical simulations to determine the contribution of the individual mechanism by history matching the results of laboratory tests collected previously. The one-D mechanistic numerical model was then upscaled to a synthetic homogeneous 3D model by simulating a quarter of the 5-spot sector model to evaluate the feasibility and engineering design of ICE for future field scale pilot tests and potential prize of ICE EOR. After comparing the base case with urea injection, a sensitivity analysis was performed. As part of the aims, the simulation results differentiate and reveal the incremental contributions of the synergetic behaviors among several mechanisms: oil viscosity reduction, oil swelling, and IFT reduction. Data also showed that the IFT reduction plays a rather minor role in this effort, and its contribution is basically indistinguishable. The predominant recovery mechanisms are mainly controlled by oil swelling and viscosity reduction; temperature plays a key role in influencing the extent of reaction kinetics of urea. In the 1D simulation, the temperature significantly impacted the production performance as the core cooled down quickly. In a 3D or field-scale scenario, the waterflooding does not change the in-depth reservoir temperature as the temperature gradient moves at a much slower rate (about two times slower) than the injected urea solution slug. However, the duration of water flooding should be considered for field project design as it may alter the temperature profile in the reservoir.
Abstract Wellbore instability is a major preoccupation during drilling operations and is highly dependent of the physiochemical features of the drilling mud. The hydrophilic clays are used in making drilling mud as they provide extensive viscosity and gel strength, and other rheological properties important for optimum drilling mud performance. However, the segregation of the suspended particles of the once optimum mud to create mud cake against the wellbore formation leads to phases imbalance in the mud system, degrading the physiochemical characteristics of the now worn-out mud after several cycling in and out of the well. Although it is crucial to consider the influence of bottomhole conditions in mud rheological alteration, it is necessary to highlight the direct correlation of most mud physiochemical features with the swelling index of the mud. Therefore, optimization of drilling mud is still up to date mostly about swelling control of the mud thus solid-liquid balancing. Overtime, research papers addressing drilling mud enhancement transitioned from mechanical means such as Loss Circulation Materials (LCM) to chemical additives including polymers which as economically profitable and have swelling abilities. Polyvinyl alcohol one most desirable polymers for future drilling fluid designing as it has proved to influence mud rheology and cake filtration positively. Therefore, this study is an attempt to assess the impact of polyvinyl alcohol on wellbore isolation of a water-based drilling mud. The experiment included two types of Polyvinyl Alcohol (PVOH): Non-ionic PVOH and Cationic PVOH. Each PVOH was added to a set of 3 samples at concentrations 0.1, 0.3, and 0.5 wt.%. An additional sample with no polymer was used as a reference sample. The samples were each subjected to 5h of static pressurized filtration at atmospheric temperature. After which Spectral analysis where performed, and Permeability estimated using Darcy's Law. The results show significant influence on Polyvinyl Alcohol on mud phases distribution. Major dehydration of samples was observed as the sample without PVOH recorded the highest filtrate production while the samples with Cationic, Non-Ionic, and Conventional PVOH had average reduction of 21%,38%, and 43% respectively. The mud cake permeability of samples drastically drops at the least concentration of PVOH with a noticeable difference in permeability despite having the same PVOH concentrations. Those differences are attributed to PVOH-specific structural compositions. This study provides evidence of Polyvinyl Alcohol being responsible for improving mud thermal stability while helping any industry applying drilling activities to expand the range of polymer types that can be used to attain the desired drilling mud for a particular formation.
Ge, Xiaojing (Missouri University of Science and Technology) | Biheri, Ghith (Missouri University of Science and Technology) | Imqam, Abdulmohsin (Missouri University of Science and Technology) | Bai, Baojun (Missouri University of Science and Technology) | Zhang, Yuwei (Missouri University of Science and Technology)
Abstract High viscosity friction reducers (HVFRs) are widely used as friction-reducing agents and proppant carriers during hydraulic fracturing. The reuse of produced water has gained popularity due to environmental and economic benefits. Currently, the field’s most commonly used friction reducers are anionic and cationic HVFRs. Anionic HVFRs are typically pumped with freshwater, while cationic HVFRs are used with high Total Dissolved Solids (TDS) produced water. Cationic friction reducers are believed to have better TDS tolerance, friction reduction performance, and proppant transport capabilities compared to anionic friction reducers under high TDS conditions due to their superior viscoelastic properties. In addition, the impact of different anions and cations on the viscosity of HVFRs has been thoroughly studied, and viscosity reduction mechanisms include charge shielding, increasing the degree of hydrolysis, and forming coordination complexes. However, anions and cations’ effects on the elasticity of HVFRs still remain to be investigated. Besides, most previous experimental studies either do not specify experimental procedures or control the experimental variables well. Therefore, the ultimate objective of this experimental study is to analyze various cations and anions’ effects on the elasticity of anionic and cationic HVFRs comparably and precisely with experimental variables well controlled. Two hypotheses based on anions and cations’ effects on the viscosity of HVFRs are proposed and will be tested in this study. First, the elasticity reduction of anionic HVFRs is mainly due to cations, whereas the elasticity reduction of cationic HVFRs is mainly due to anions. Second, the salts’ effects on the elasticity reduction of HVFRs should follow the same trend as the salts’ effects on the viscosity reduction of HVFRs. For anionic HVFRs, monovalent Alkali metals should have a similar effect; divalent Alkaline earth metals should have a similar effect; transition metals should have the most severe effect. For cationic HVFRs, SO4 should have more pronounced effects than Cl. To demonstrate both hypotheses, an anionic and a cationic HVFR at 4 gallons per thousand gallons (GPT) were selected and analyzed. The elasticity measurements of both anionic and cationic HVFRs were conducted with deionized (DI) water and various salts respectively. Fe and H (or pH) effects were specifically investigated. The results showed both hypotheses were accepted.
Zhang, Junjing (ConocoPhillips Company) | Nozaki, Manabu (ConocoPhillips Company) | Zwarich, Nola R (ConocoPhillips Company) | Carman, Paul S (ConocoPhillips Company) | Davis, Eric R (ConocoPhillips Company) | Pedam, Sandeep (ConocoPhillips Company) | Buck, Brian R (ConocoPhillips Company) | Childs, Leigh A (ConocoPhillips Company) | Perfetta, Patrick J (ConocoPhillips Company)
Abstract In thinly bedded sandstone reservoirs, hydraulic fractures are required in horizontal wells to connect isolated pay intervals and to improve the volumetric sweep efficiency during waterflooding. This study presents a new, more robust way to evaluate gel damage and cyclic stress in the laboratory. Results from the laboratory evaluation are validated with field production data. Standard ISO/API tests are adequate at comparing proppant types but do not accurately predict resultant conductivity in a well as they do not account for several in-situ damage mechanisms. With a limited number of cores available it is important to clearly define the scope of the laboratory testing and decide which damage mechanisms to investigate. Testing all variables in the laboratory is not practical. For this study, the primary objectives were to 1) compare ceramic proppant to the natural sand, 2) investigate the impact of thinly-bedded sandstone on the fracture conductivity, and 3) determine the minimum required proppant concentration (the cutoff concentration for interpreting the effective fracture half-length in numerical hydraulic fracture model results). The laboratory testing was designed to simulate as realistic the in-situ condition by 1) using actual formation core, 2) performing cyclic stress cycles to mimic multiple shut-in and production periods, and 3) placing the gel and allowing it to cross-link and break in the fracture. During the conductivity experiments, the following steps were taken: 1) oil injection with cyclic stress applied, 2) dynamic cross-linked gel injection and shut-in for gel breaking, and 3) oil injection with cyclic stress applied. Variables investigated include fluid-rock interaction, gel residual, cyclic stress, proppant type, concentration, and size distribution and time dependency of conductivity. Discount factors are derived from the test results which provide a more realistic and repeatable conductivity prediction. This study discovered that for hydraulic fracturing of weak rocks in the shallow formation, the baseline fracture conductivity from API tests should be reduced by 22% first to account for the proppant-rock interaction. After applying the aggressive cyclic stresses, the cumulative conductivity loss increases to 38%. After the cross-linked gel cleanup, a total of 72% fracture conductivity is lost for a proppant pack at 2 lbm/ft and 91% conductivity loss for proppant pack at 1 lbm/ft. It is also found in this study that each large-scale stress cycle reduces an approximate 1% fracture conductivity of the loosely packed proppant until a tighter and stable proppant pack is formed. The cyclic stress effect becomes insignificant when the proppant pack porosity decreases to ∼0.2. Well production history was matched by varying fracture properties in the transient inflow performance analysis. For two wells under the same fracture design, the matched fracture conductivities resulted in less than 25% error compared with the retained conductivities from the laboratory tests. This validated the laboratory findings and method. In summary, this study investigates a critical completion design variable and well performance modeling input, i.e., fracture conductivity, in low-to-moderate permeability, thinly bedded sandstone reservoirs. It breaks down the fracture conductivity degradation into various components and enables further fracturing design optimization, such as proppant selection, fracturing fluid qualification, pump schedule design, well shut-in frequency, frac sleeve spacing, etc. It provides an unbiased estimate of retained fracture conductivity after considering the major impairment mechanisms. It also prevents fictitious and overly optimistic fracture conductivities which originate from the fracturing practices in unconventional reservoirs and the continuous drive for cost savings. This results in calculations of completion skin factors that more accurately represent the fracture conductivity for longitudinal fractures in openhole sleeve completions, reinforcing the importance of fracture design optimization on well productivity.
Murtaza, Mobeen (King Fahd University of Petroleum & Minerals) | Tariq, Zeeshan (King Abdullah University of Science and Technology) | Kamal, Muhammad Shahzad (King Fahd University of Petroleum & Minerals) | Rana, Azeem (University of Management & Technology, Lahore) | Patil, Shirish (King Fahd University of Petroleum & Minerals) | Mahmoud, Mohamed (King Fahd University of Petroleum & Minerals) | Al-Shehri, Dhafer (King Fahd University of Petroleum & Minerals)
Abstract Clay swelling and dispersion in tight sandstones can have an influence on the formation's mechanical properties and productivity. Hydraulic fracturing is a typical stimulation technique used to increase the production of sandstone formations that are too compact. The interaction of clay in sandstone with a water-based fracturing fluid causes the clays to disperse and swell, which weakens the rock and reduces its productivity. Several swelling inhibitors, including inorganic salts, silicates, and polymers, are regularly added to fracturing fluids. Concerns linked with these additions include a decrease in production owing to formation damage and environmental concerns associated with their disposal. In this study, we introduced naturally existing material as a novel green swelling inhibitor. The performance of the novel green inhibitor was examined by its impact on the mechanical properties of the rock. Acoustic strength and scratch tests were conducted to evaluate rock mechanical parameters such as unconfined compressive strength. Further inhibition potential was evaluated by conducting linear swell and capillary suction timer tests. The contact angle was measured on a sandstone surface for wettability change. The results showed the novel green additive provided strong inhibition to clays. The reduction in linear swelling and rise in capillary suction time showed the inhibition potential and water control potential of the biomaterial. Furthermore, mechanical properties were lower than DI-treated rock sample tested under dry conditions. With all these benefits, using green novel additive makes rock more stable and reduces damage to the formation. The green additive is economical and an environment-friendly solution to clay swelling. It is an effective recipe for reducing the formation damage caused by clay swelling.
Bulule, Valcia (West Virginia University) | Sattari, Arya (West Virginia University) | Aminian, Kashy (West Virginia University) | El Sgher, Mohamed (West Virginia University) | Samuel, Ameri (West Virginia University)
Abstract The shale formations, in addition to the gas present in the pores of the rock, contain gas in the adsorbed state in the organic matter within the rock. As the pressure depletes in the reservoir the adsorbed gas is released and augments the gas production. In addition, gas desorption can potentially lead to permeability enhancement due to shale matrix shrinkage. At the same time, the pressure depletion increases the effective stress causing shale permeability and hydraulic fracture conductivity impairments. The purpose of this study was to investigate the impact of the gas desorption on the productivity of Marcellus shale horizontal well with multiple hydraulic fracture stages. The impacts of hydraulic fracture properties including half-length, conductivity, and stage spacing on gas desorption were also investigated. To investigate the impact of the gas desorption on gas production from Marcellus shale, a reservoir model for a horizontal well completed with multiple hydraulic fracture stages was used. The model has been developed based on the available information from several existing Marcellus shale horizontal wells in West Virginia. The laboratory and published data relative to adsorbed gas and the geomechanical factors were analyzed and geomechanical multipliers were generated and incorporated in the model. The geomechanical multipliers account for the impairments in hydraulic fracture conductivity and the reduction in the formation (matrix and fissure) permeability as well as the shale shrinkage caused by the reservoir depletion. The model was then utilized to investigate the impact of different parameters including Langmuir pressure and volume, fracture half-lengths, fracture spacings, and fracture conductivity on gas desorption and gas production. The inclusion of geomechanical multipliers provided more realistic production predictions and better understanding of the desorbed gas impact. The gas desorption was found to have a significant impact on the productivity during later stages of the production. This is contributed to pressure depletion required for desorption to become significant. The contribution of the desorbed gas to production increases as the fracture half-length increases and the fracture spacing decreases. Therefore, it can be concluded that desorption of gas depends on the stimulated reservoir volume.
Abstract Compressor performance maps are a key feature of gas pipeline simulations. This paper explains the physics behind centrifugal compressor performance maps. Included are the thermodynamics of gas compression, the aerodynamics of centrifugal compressors, as well as the function of important subsystems such as seals and surge control devices. Control mechanisms for centrifugal compressors are explained and their impact on performance maps are discussed. The impact of different drivers on control concepts is also addressed. The properties of the gas to be compressed, and its impact on relevant compressor performance parameters will be analyzed, and the use of equations of state is addressed. The aerodynamic components of compressors are analyzed with regards to their impact on compressor performance. Based on these foundations, the connection between the flow physics of gas compressors and the resulting performance maps, which represent the behavior of the device to be simulated, is drawn, and explained.