Low temperature and high pressure conditions favor the formation of gas clathrate hydrates which is undesirable during oil and gas industries operation. The management of hydrate formation and plugging risk is essential for the flow assurance in the oil and gas production. This study aims to show how hydrate management in the deepwater gas well testing operations in the South China Sea can be optimized. To prevent the plugging of hydrate, three hydrate management strategies are investigated. The first method, injecting thermodynamic hydrate inhibitor (THI) is the most commonly used method to prevent hydrate formation. THI tracking is utilized to obtain the distribution of mono ethylene glycol (MEG) along the pipeline. The optimal dosage of MEG is calculated through further analysis. The second method, hydrate slurry flow technology is applied to the gas well. Pressure drop ratio (PDR) is defined to denote the hydrate blockage risk margin. The third method is the kinetic hydrate inhibitor (KHI) injection. The delayed effect of KHI on the hydrate formation induction time ensures that hydrates do not form in the pipe. This method is effective in reducing the injection amount of inhibitor. The problems of the three hydrate management strategies which should be paid attention to in industrial application are analyzed. This work promotes the understanding of hydrate management strategies and provides guidance for hydrate management optimization in oil and gas industry.

In this paper, pragmatic and robust techniques have been developed to simultaneously interpret absolute permeability and relative permeability together with capillary pressure in a naturally fractured carbonate formation from wireline formation testing (WFT) measurements. By using two sets of pressure and flow rate field data collected by a dual-packer tool, two high-resolution cylindrical near-wellbore numerical models are developed for each dataset on the basis of single- and dual-porosity concepts. Then, simulations and history matchings are performed for both the measured pressure drawdown and buildup profiles, while absolute permeability is determined and relative permeability is interpreted with and without considering capillary pressure. Compared to the experimentally measured relative permeability curves for the same formation collected from the literature, relative permeability interpreted with consideration of capillary pressure has a better match than those without considering capillary pressure. Also, relative permeability obtained from dual-porosity models has similar characteristics to those from single-porosity models especially in the region away from the endpoints, though the computational expenses with dual-porosity models are much larger. Absolute permeabilities in the vertical and the horizontal directions of the upper layer are determined to be 201.0 mD and 86.4 mD, respectively, while those of the lower layer are found to be 342.9 mD and 1.8 mD, respectively. Such a large vertical permeability of the lower layer reflects the contribution of the extensively distributed natural fractures in the vertical direction.

Self-healing wind turbine blades offer a substantial offset for costly blade repairs and failures. We discuss the efforts made to optimize the self-healing properties of wind turbine blades and provide a new system to maximize this offset. Copper wire coated by paraffin wax was embedded into fiber-reinforced polymer (FRP) samples incorporated with Grubbs' first-generation catalyst. The wires were extracted from cured samples to create cavities that were then injected with the healing agent, dicyclopentadiene (DCPD). Upon sample failure, the DCPD and catalyst react to form a thermosetting polymer to heal any crack propagation. Three-point bending flexural tests were performed to obtain the maximum flexural strengths of the FRP samples before and after recovery. Using those results, a hierarchy of various vascular network configurations was derived. To evaluate the healing system's effect in a real-life application, a prototype wind turbine was fabricated and wind tunnel testing was conducted. Using ultraviolet (UV) dye, storage and transport processes of the healing agent were observed. After 24 h of curing time, Raman spectroscopy was performed. The UV dye showed dispersion into the failure zone, and the Raman spectra showed the DCPD was polymerized to polydicyclopentadiene (PDCPD). Both the flexural and wind tunnel test samples were able to heal successfully, proving the validity of the process.

Drillstrings that include one or more axial oscillation tools (AOTs) are referred to as axial oscillation-supported drillstrings. Downhole vibrations induced by these tools in the drillstring are the most efficient method for friction reduction and improving axial force transfer in high-angle and extended-reach wells. Functional testing of axial oscillation tools prior to downhole operations and modeling the dynamic response of axial oscillation-supported drillstring systems are required to predict the performance and functionality of AOTs. This study presents a practical approach for functional testing of axial oscillation tools and a new analytical model for predicting the dynamic response of axial oscillation-supported drillstrings operating at surface conditions. The axial oscillation-supported drillstring is modeled as an elastic continuous system subjected to viscous damping, frictional contact, and displacement (support excitation). The functional test is a unique experimental test procedure designed to measure the pressure drop, pressure fluctuations, and axial displacement of an axial oscillation tool while varying the flow rate and the spring rate of the tool. The introduction of the spring rate as a variable in the new model and functional testing is unique to this study and not considered in the existing literature. Axial displacement and acceleration predicted from the new model closely agrees with the results obtained from the functional tests. The accuracy of the model is also validated with the results of two previously published functional tests. The comparisons demonstrate an average deviation of approximately 14.5% between predictions and measurements. The axial displacement and pressure drop of AOT increased with flow rate or oscillation frequency. The amplitude of axial displacement increased with frequency because of increased pressure drop.

The program involves the application of a novel gasification concept, termed a modular allothermal gasifier (MAG) to produce syngas from coal, biomass, and waste slurries. The MAG employs a steam-driven gasification process using a pressurized entrained flow reactor wherein the external wall surfaces are catalytically heated to 1000 °C via heterogeneous combustion of a portion of the produced syngas. The MAG can be fed by a hydrothermal treatment reactor for biomass and waste feedstocks, which employs well-developed hydrothermal processing technology using the addition of heat and water to provide a uniform slurry product. The hydrothermal treatment reactor requires no preprocessing and a clean syngas is produced at high cold gas efficiency (80%). Importantly, the MAG can operate over a wide range of positive pressures up to 3 MPa (30 bar) which provides process control to vary the output to match end-use needs or feedstock rate. The system produces minimal emissions and operates at significantly higher efficiency and lower energy requirements than pyrolysis, plasma gasification, and carbonization systems. The system is compact and modular, making it easily transportable, for example, to a variety of sites, including those where remoteness, inaccessibility, and space limitations would preclude competing systems. The system can be applied to small gasification systems without the increase in heat losses that plague conventional small scale gasifiers. Test results and model simulations are presented on a single tube system and analyses of a variety of configurations presented.

Well cements are an important aspect of wellbore integrity and recent investigations focus on describing the cement lifetime using, when possible, nondestructive tests like ultrasonic measurements. However, the original API and ASTM testing standards were based on destructive mechanical testing of cements, leading to the decision to investigate the backward and forward compatibility between ultrasonic measurements and mechanical testing, which makes the subject of this work. Ultrasonic cement measurement became a very popular method to assess the mechanical properties of the cement in a nondestructive manner. Since various measurement systems exist on the market, the development of an accurate reference data base that can be used to calibrate such measurements becomes very important. Two major systems have therefore been compared: the ultrasonic compressive strength, using the ultrasonic pulse velocity (UPV) principle, and the unconfined compressive strength (UCS), using the standard testing frame according to API and ASTM standards. The tests have been performed at different curing times, using both devices, on API Class G cements with bentonite and other additives. This paper presents the results of over 200 experiments that have displayed a different UPV response as a function of the additive content. Cement specific UPV versus UCS correlations were established. Thereby, a new level of accuracy was reached. Moreover, it was observed that after a given curing time, depending on the additive and its concentration, the UPV response is not as sensitive as the results yielded by the UCS method. The outcomes are an important step forward to improve and understand the wellbore integrity.

The study here presents laboratory testing results of Class F fly ash geopolymer for oil well cementing applications. The challenge reported in literature for the short thickening time of geopolymer ash has been overcome in this study, where more than 5 h of the thickening time is achievable. API Class H Portland cement used a controller on all the tests conducted in this work. Tests conducted in this research include unconfined compressive strength (UCS), shear bond strength, thickening time, shrinkage, free water, and cyclic and durability tests. Results indicate temperature as a crucial factor affecting the thickening time of geopolymer mix slurry. UCS testing indicates considerably higher compressive strength after one and fourteen days of curing for geopolymer mixtures. This indicates gaining strength with time for geopolymer mixture, where time retrogression effects are observed for Portland cements. Results also indicate higher shear bond strength for geopolymer mix that can better tolerate debonding issues. Additionally, more ductile material behavior and higher fracture toughness were observed for optimum geopolymer mixes. Tests also show applicability of these materials for deviated wells as a zero free water test was observed.

The current state of the art in waste heat recovery (WHR) from internal combustion engines (ICEs) is limited in part by the low temperature of the engine coolant. In the present study, the effects of operating a diesel engine at elevated coolant temperatures to improve utilization of engine coolant waste heat are investigated. An energy balance was performed on a modified three-cylinder diesel engine at six different coolant temperatures (90 °C, 100 °C, 125 °C, 150 °C, 175 °C, and 200 °C) and 15 different engine loads to determine the impact on waste heat as the coolant temperature increased. The relative brake efficiency of the engine alone decreased between 4.5% and 7.3% as the coolant temperature was increased from 90 °C to 150 °C. However, the engine coolant exergy increased between 20% and 40% over the same interval. The exhaust exergy also increased between 14% and 28% for a total waste heat exergy increase between 19% and 25%. The engine condition was evaluated after testing and problem areas were identified such as overexpansion of pistons, oil breakdown at the piston rings, and head gasket seal failure.

Thermocells convert heat energy directly into electrical energy through charge-transfer reactions at the electrode–electrolyte interface. To perform an analytical study on the behavior of thermocells, the Onsager flux relationship was applied to thermocells, which used aqueous copper II sulfate and aqueous potassium ferri/ferrocyanide as the electrolyte. The transport coefficient matrices were calculated for each electrolyte and applied to several simulations, which were subsequently validated through experimental testing and comparison to previous literature results. The simulation is shown to correctly predict the short circuit current, maximum power output, and power conversion efficiency. Validation demonstrates that the simulation model developed, using the Onsager flux equations, works for thermocells with different electrode materials (platinum, copper, charcoal, acetylene black, and carbon nanotube), electrode spacing, and temperature differentials. The power dependence of the thermocell on concentration and electrode spacing, with respect to the Seebeck coefficient, maximum power output, and relative efficiency, is also shown.

Radial jet drilling (RJD) is an efficient approach for improving the productivity of wells in low permeability, marginal and coal-bed methane (CBM) reservoirs at a very low cost. It uses high-pressure water jet to drill lateral holes from a vertical wellbore. The length of the lateral holes is greatly influenced by the frictional resistance in the hole deflector. However, the hole deflector frictional resistance and structure design have not been well studied. This work fills that gap. Frictional resistances were measured in a full-scale experiment and calculated by numerical simulation. The structure of the hole deflector was parameterized and a geometric model was developed to design the hole deflector track. An empirical model was then established to predict the frictional resistance as a function of the hole deflector structure parameters and an optimization method for designing the hole deflector was proposed. Finally, four types of hole deflectors were optimized using this method. The results show good agreement between the numerical simulation and the experimental data. The model error is within 11.6%. The bend radius R and exit angle β are the key factors affecting the performance of the hole deflector. The validation test was conducted for a case hole deflector (5½ in. casing). The measured frictional resistance was decreased from 31.44 N to 23.16 N by 26.34%. The results from this research could serve as a reference for the design of hole deflectors for radial jet drilling.

Much of the aerodynamic design of wind turbines is accomplished using computational tools such as XFOIL. These codes are not robust enough for predicting performance under the low Reynolds numbers found with small-scale wind turbines. Wind tunnels can experimentally test wind turbine airfoils to determine lift and drag data over typical operating Reynolds numbers. They can also test complete small wind turbine systems to determine overall performance. For small-scale wind turbines, quality experimental airfoil data at the appropriate Reynolds numbers are necessary for accurate design and prediction of power production.

An abnormal phenomenon may occur during gas-well testing: the wellhead pressure initially rises and then drops when shutting-in a well; the wellhead pressure initially drops and then rises when opening a well. To determine why and how this phenomenon occurs, a transient nonisothermal wellbore flow model for gas-well testing is developed. Governing equations are based on depth- and time-dependent mass, momentum equations, and the gas state equation. Temperature is predicted using the unsteady-state heat transfer model of Hasan. Boundary conditions include the restriction of formation inflow and wellhead throttling to the flow. The difference equations are established based on the implicit central finite difference method. The model can simulate the influences of temperature and flux (mass velocity). The model also considers the effects of formation inflow and surface throttling on the system. The results indicate wellhead pressure under flowing temperature is higher than that under static temperature, thus causing the abnormal phenomenon. A larger pressure difference makes the abnormal phenomenon more significant. Without considering temperature variation, simulated wellhead pressure would not exhibit the abnormity. Without considering flux variation, simulated pressure curve is not smooth. A new model has thus been validated using a gas field example.

Three individual wave power generation technologies were studied and evaluated using multicriteria decision analysis through the use of the PROMETHEE method. To evaluate the three technologies, data were collected from previously performed experimental testing on the performance of each wave power generation technology. These data were used to feed into seven different criteria; namely the capacity factor, rated power, capital cost, operation and maintenance (O&M) costs, cost of electricity (COE) for a 10 year payback, maturity, and survivability. The associated data and criteria were used to determine the optimal technology. The results from the Decision Lab modeling ranked the Wave Dragon, AquaBuOY, and Pelamis technologies as 1, 2, and 3, respectively, for all three locations: Tofino/Ucluelet, Hibernia Oil Platform, and St. John's, Newfoundland. A sensitivity analysis of the threshold values determined for the baseline modeling indicated that the original ranking was essentially unaffected when the threshold values were modified (increased and decreased). The weights of the criterion were individually adjusted to evaluate any change in ranking order. A sizable increase in weighting of greater than 40% of any one criterion (while the others were weighed equally) resulted in a change of the overall ranking order of the three technologies. Final weightings on each of the criterion were assigned with preference on rated power, COE, and maturity stage. All other criteria were weighted equally and like the baseline modeling output, the results of the model ranked Wave Dragon, AquaBuOY, and Pelamis from most favorable to least favorable for all three of the locations analyzed.

Predicting erosion resulting from the impact of solid particles such as sand is a difficult task, since it is dependent on so many factors. The difficulty is compounded if the particles are entrained in multiphase flow. Researchers have developed models to predict erosion resulting from solid particles in multiphase flow that account for a variety of factors. However, no model currently accounts for the flow orientation on the severity of erosion. This work provides three sets of experimental results that demonstrate pipe orientation can have a significant impact on the amount of erosion for annular flow. A semimechanistic model to predict erosion in annular flow is also outlined that accounts for the upstream flow orientation.

Characteristics of dynamic hydrocyclones are introduced. The advantages of dynamic hydrocyclones, such as wider applicable flowrate range, smaller cut size, etc., are analyzed compared with normally used static hydrocyclones. By analyzing the inside velocity field distributions, the reason why dynamic hydrocyclones have higher efficiency than static ones is further described. Laboratory experiments and field tests of dynamic hydrocyclones were carried out. Relationships of flowrate, outer shell rotation speed, and split ratio with pressure were studied. Pressure and pressure drop inside hydrocyclones were measured and analyzed. The effect of main operating parameters, such as split ratio and rotation speed, on hydrocyclonic separation performance was also studied. It is shown that the rise of split ratio is beneficial for enhancing the separation efficiency, but the split ratio must be controlled in an appropriate range so as to obtain satisfactory separation results. The increase of rotation speed is helpful for the forming of an oil core inside the dynamic hydrocyclone, but the vibration phenomenon should also be avoided. Field tests, as anticipated, indicated satisfactory results.

Downhole water sink (DWS) well completions segregate production in the wellbore by producing water from the underlying aquifer and oil—from the oil zone of the reservoir. A pump drains water from the bottom completion to create a pressure drawdown that prevents water from coning up to the top, oil producing zone. Successful application of DWS technology in wells with water-coning problem requires effective isolation between the top and bottom completions of the well. Since DWS technology requires dual completion, the completion is configured for vertical interference testing. The problem is that such test involves flow of two fluids, water and oil. This paper presents a new mathematical model and analysis method for vertical interference testing using top completion (in the oil leg) for production and bottom completion (in the water leg) for observation. The model is analytical and accommodates partial penetration and permeability anisotropy. The analysis method employs a family of type-curves. Examples of possible applications of this new testing method are also shown in this paper.

This paper presents the experimental testing of relatively cost-effective expanders in an organic Rankine cycle (ORC) to produce power from low-grade energy. Gerotor and scroll expanders were the two types of expanders tested to determine their applicability in producing power from low-grade energy. The results of the experimental testing showed that both types of expanders were good candidates to be used in an ORC. The gerotor and scroll expanders tested produced 2.07 kW and 2.96 kW, and had isentropic efficiencies of 0.85 and 0.83, respectively. Also the paper presents results of an analytical model produced that predicted improved cycle efficiency with certain changes. One change was the flow rate of the working fluid in the cycle was properly matched with the inlet pocket volume and rotational speed of the expander. Also, the volumetric expansion ratio of the expander was matched to the specific volume ratio of the working fluid (R-123) across the expander. The model incorporated the efficiencies of the expanders and pump obtained during experimental testing, and combined two expanders in series to match the specific volume ratio of the working fluid. The model determined the power produced by the expanders, and subtracted the power required by the working fluid pump and the condenser fan. From that, the model calculated the net power produced to be 6271 W and the overall energy efficiency of the cycle to be 7.7%. When the ORC was simulated to be integrated with the exhaust of a stationary engine, the exergetic efficiency, exergy destroyed, and reduction in diesel fuel while still producing the same amount of power during 2500 h of operation were 22.1%, 22,169 W, and 4,012 L (1060 U.S. gal), respectively. Consequently, the model presents a very realistic design based on results from experimental testing to cost-effectively use low-grade energy.

The Hygro-Mole’s success has been proven both in the laboratory and in the Waste-management Education and Research Consortium (WERC) competition. This logging tool is designed to determine the value of low moisture content present in subsurface regions, at very low cost. The Hygro-Mole yields immediate results, and can be calibrated to specifically monitor multiple types of subsurface material. All that is required for the current design is a 0.1 m diameter borehole to the point of interest in the subsurface zone for tool access.

First oil production from a deep-water oil field is to be achieved by the installation of an initial development system (IDS). Well testing is required for field development and reservoir management. The well testing system requires high-accuracy oil and water rates to provide the data needed for decision analysis in ongoing drilling programs. The well testing system must also be integrated with other platform operations, such as well cleanup after drilling. We introduce here, the concept of a multiphase meter in series with conventional separation technology for improved process control. This feedback control loop configuration is simulated in MATLAB and shown to extend the capabilities of both technologies. The principle of gas volume fraction control in two-phase separator liquid lines is shown to be supplementary to conventional level control systems for performance enhancement of oil field well testing. Concepts demonstrated here can also be easily applied as retrofits to existing separation facilities, which show accuracy or upset problems.

Two AC signals generated by two sensors mounted in two elbows at the ends of vertical and horizontal branches of a metering pipe are simultaneously recorded and analyzed. The AC signals are mainly due to fluctuations in stagnation-pressure caused by the local oscillations of local void fraction and to transport velocity of the gas-liquid flow. Features extracted from stochastic interpretation of the two signals are strongly related to gas and liquid flowrates. Laboratory and field testing of the new meter demonstrated that, for the same gas and liquid flowrates, probability distribution functions (PDF) determined from statistical analysis of “vertical” and “horizontal” AC signals are unique. For broad ranges of gas-liquid ratios, features extracted from the PDF are linearly related to gas and liquid flowrates.