Value of Cement Bond Logs for Evaluation and Improvement of Cementing Practices in Extended Reach Drilling ERD Wells

This paper discusses the value of cement logs as the core input to analyze the cement quality and validate the improvements made to cementing designs and practices of the intermediate casing string in Extended-Reach Drilling (ERD) wells. The ERD wells are being drilled from artificial islands in a field offshore in the UAE. The primary cementing objectives are isolating the reservoirs from their sublayers and protecting the casing against possible future corrosion across an upper formation. Cementing challenges include higher angle deviation, higher mud weight requirements resulting from an anisotropic, unstable shale formation present above the reservoir section. Effective reservoir management requires sound zonal isolation to eliminate crossflow between different reservoir units. In combination with standard cement bond logs (CBL), ultrasonic technology has provided detailed information about cement quality and a qualitative indication of casing position in the borehole. These have also led to valuable insight into how continued cementing designs and practices improved zonal isolation. Improvements in cement quality seen as a result of enhanced casing centralization, optimized hydraulic model, modified cement rheology, displacement rate impact, among others, were confirmed with the cement log evaluation program. The paper will present the ultrasonic and standard CBL responses, which support the enhancements made to the cementing design and practices that yield the desired results. The cement quality has been improved in the ERD wells intermediate section through strategic modification in cementing practices. Cement evaluation logs have played a significant role in validating the cementing methods’ development. Consistently improved zonal isolation results have opened up the opportunity for future efficiency gains by eliminating routine CBL.

Innovative Drilling Fluid Technology Conquered Tough Geomechanics Offshore Mexico

The reservoir field highlighted in this paper is located Offshore Mexico in the southeast part of Campeche Bay and hidden below a troublesome, unstable formation that must be transacted before reaching the new production zone. During the exploration phase, this section experienced severe lost circulation and unstable conditions before reaching the final depth. Based on lessons learned, the team worked to develop a best- practices approach using geomechanics analysis and a novel fluid technology which enabled the operator to safely drill through this problematic intermediate section under high-pressure, high-temperature (HPHT) conditions. The methodology started with identifying the geomechanics challenges, implementing operational best practices, and finally, use of an innovative, low-invasion fluid technology, which creates a thin and impermeable shield at the wellbore wall, effectively sealing the fractures and preventing fracture propagation in the highly unstable formation of interspersed carbonates, shales, and sandstones. The strong mechanical properties of the thin, but firm, barrier created at the wellbore wall minimized the destabilizing effect of fluid invasion. Synergy from the geomechanical team, best practices for the operation, and innovative drilling fluid technology solved the wellbore instability drilling challenge encountered in the exploration well. In offset wells, losses of more than 2,200 m3 of drilling fluid, stuck pipe, and major NPT were observed. By incorporating the shielding technology, wellbore instability was improved in the intermediate section. In addition, the fluid technology was easily pumped through the bottomhole assembly (BHA) to seal formation fractures between 2,000 and 3,000 μm in size. This well, utilizing the barrier technology to mitigate the wellbore instability and drill within a narrow fracture gradient operating window, was the first in the area to have zero loss of drilling fluid as compared to the typical 5 to 10-m3/hr circulation losses experienced during exploration drilling in the intermediate section characterized by interbedded layers of carbonates, shales, and sandstone under high-pressure, high-temperature (HPHT) conditions. The coordination between the teams using best practices was critical to meeting the challenge of the intermediate geomechanically weak formation. This case history in offshore Mexico will demonstrate both the importance of teamwork and the utilization of a proven technology that improves wellbore instability, minimizes NPT, mitigates pipe tripping issues and avoids huge volumes of drilling fluid lost into the geomechanically weak formation. This barrier technology can be applied globally to troublesome formations - such as interbedded carbonates, shales, and sandstones - to improve operations and provide cost savings for the operator.

Experimental study on soft PSD material of dual pulse solid rocket motor

In order to study the failure reason of the soft PSD in the dual pulse solid rocket motor (SRM), the deformation process of the intermediate section of the second pulse combustion chamber was simplified to the two-dimensional plane strain state, and the calculation method of the circumferential strain of the soft PSD was obtained. The influencing factors of the circumferential strain of the soft PSD were studied. The main factors affecting the circumferential strain of the soft PSD are the gap between the soft PSD and the propellant grain, and the circumferential strain on the inner surface of the propellant grain. The calculation method could be used to initially estimate the circumferential strain of the soft PSD, and then predict the rationality and feasibility of the design scheme. The apparent morphology and area change rate of EPDM materials of PSD under different strains were studied by DIC tensile test. The variation of the porosity of the EPDM material with the increase of strain was obtained by micro-CT. By comparing the SEM results of the fracture and the slit of the tensile test piece, the failure mode of the EPDM material of PSDs was determined, and the failure mechanism of the PSD structure was obtained. The conclusions obtained in this paper can provide a useful reference for the design of the PSD in dual pulse SRM.

Hydrodynamic design of an advanced submerged propulsion

A new kind of advanced submerged propulsion is automatically modeled and analyzed based on the hydrodynamic and cavitation performance. A mathematical algorithm is proposed to describe the fusion-duct, which is controlled by several design parameters, including section diameters, section lengths, and inlet shape and aspect ratio. The hydrodynamic performances of 13 cases with different parameter combinations are numerically simulated. The simulation is carried out by solving the Reynolds Average Navier-Stokes equations with STAR-CCM+, and the SST k-ω turbulence model is applied. The curves of rotor thrust and torque, stator thrust and duct resistance, along with efficiency and merit coefficient are obtained as functions of the advance coefficient and are compared for different cases. Meanwhile, the pressure distribution on both sides of the rotor and the flow field of intermediate section are systematically analyzed. To guide future designs, an impact factor is further defined and calculated to quantify the effects of different parameters. The results indicate that the section diameters have the most significant influence on hydrodynamic and cavitation performances.

Analytical and Experimental Study on CAP1000 Guide Tube Assembly

The guide tube (GT) representation in the reactor-internal system model has been crude and inaccurate in the past because the lack of experimental data on a) the rotary stiffness of the hold down bolt joint and b) the rotary stiffness of the support pins. In addition, the slotted enclosure and the complex interior in the continuous section further complicated the modeling accuracy. In this paper, the static and dynamic characteristic of the domestically manufactured CAP1000 guide tubes are studied both experimentally and analytically. Using the stiffness data obtained from the tests and combined with the enclosure stiffness calculated from the detailed 3D finite element models, i.e., one for the intermediate section and one for the continuous section, a simplified model of the GT was established. Using the simplified model, the dynamic characteristics (natural frequency and modal shapes) were compared to the dynamic test results in the aerial condition. It can be concluded that the simplified guide tube model is believed to be the most accurate one, by far, to be used in reactor-internal system analyses.

Comparison of using different bridge prosthetic designs for partial defect restoration through mathematical modeling

ABSTRACT Objective: To analyze the stress–strain states of bone and abutment teeth during the use of different prosthetic designs of fixed partial dentures with the use of relevant mathematical modeling principles. Materials and Methods: The use of Comsol Multiphysics 3.5 (Comsol AB, Sweden) software during the mathematical modeling of stress–strain states provided numerical data for analytical interpretation in three different clinical scenarios with fixed dentures and different abutment teeth and demountable prosthetic denture with the saddle-shaped intermediate part. Statistical Analysis Used: Microsoft Excel Software (Microsoft Office 2017) helped to evaluate absolute mistakes of stress and strain parameters of each abutment tooth during three modeled scenarios and normal condition and to summarize data into the forms of tables. Results: In comparison with the fixed prosthetic denture supported by the canine, first premolar, and third molar, stresses at the same abutment teeth with the use of demountable denture with the saddle-shaped intermediate part decreased: at the mesial abutment tooth by 2.8 times, at distal crown by 6.1 times, and at the intermediate part by 11.1 times, respectively, the deformation level decreased by 3.1, 1.9, and 1.4 times at each area. Conclusions: The methods of mathematical modeling proved that complications during the use of fixed partial dentures based on the overload effect of the abutment teeth and caused by the deformation process inside the intermediate section of prosthetic construction.

Morphological Study of the Anterior Surface of the Distal Radius

The shape of the anterior surface of the distal radius is important for designing a distal radius plate for wrist fracture surgery. The aim of this study was to describe the shape of the anterior surface of the distal radius and to compare the results between female and male. We used 90 sides from three-dimensional radial models based on computer tomography images from Korean adult cadavers for this study. The anterior surface was measured in two dimensions in the coronal view, and we sectioned the anterior surface of the models to obtain intermediate and radial sections to measure the curved shape of the anterior surface in sagittal view. Several parameters were statistically different between females and males; however, there were no differences between the right and left sides for any parameters. The width of the anterior surface in the coronal view was larger in males than females, and the curved part of the anterior surface of the males was longer and more concave than that of females. In both the female and male specimens, the intermediate section was longer and more concave than the radial section. Our results are useful for anthropological studies and for designing distal radial plates.

Laser-Based Investigation on a Dry Low Emission Industrial Prototype Burner at Atmospheric Pressure Conditions

Experiments were performed at atmospheric pressure conditions on the prototype 4th generation DLE burner. The combustion changes that occur for alteration of the operating conditions by changing the equivalence ratios (ϕ) for CH4 as fuel at different sections of the burner, were optically investigated. The burner assembly has three concentrically arranged premixed burner sections: an outer Main section, an intermediate section (Pilot) and a central pilot body or pre-chamber combustor, called RPL (Rich-Pilot-Lean) section. All sections are facilitated to vary equivalence ratios to achieve optimal combustion. Planar laser-induced fluorescence (PLIF) of OH radicals and flame chemiluminescence imaging were applied to study the local flame characteristics in order to investigate turbulence-flame interaction and formation of reaction zone at the burner exit. The results show that the position and shape of the flame are clearly affected by the variation of equivalence ratios at different sections of the burner. During the experiments, first the RPL, then the Pilot and the Main flame were added in a step wise manner keeping constant the total air flow for the global ϕ = 0.5 in order to understand the flame contributions from the different combustion sections. It is observed that for the RPL fuel lean conditions, the primary combustion starts and reaches completion before exiting the burner throat while for rich conditions, the residual fuel escapes out through the RPL exit with primary combustion products and starts secondary combustion along with the Pilot and Main combustion. At the global ϕ = 0.5, for changing the RPL ϕ from lean to rich conditions, the flame stabilization region moves downstream of the burner exit and the flame front fluctuation along inner shear layer increases. For increasing the global ϕ and increasing the Pilot fuel ratio (PFR) without changing the RPL and the global ϕ, the total extension of the flame becomes shorter and the flame stabilization region moves upstream.

Influence of heat transfer on two-phase flow behavior in onshore oil pipelines

<p>Computational tools for simulation of multiphase flow in oil pipelines are of great importance for the determination of the technical feasibility of the production in oilfields. The present article presents the mathematical and numerical modeling of the oil biphasic flow in a partially submerged onshore pipeline. The biphasic behavior of the heavy oil of 13,2ºAPI is translated by the Dukler correlation. The oil’s viscosity is regarded as dependent on the temperature and on the API density of the oil by means of the Hossain correlation. The pipeline, of 3,600m and 4 inches (10.16cm) in diameter, transports the oil from a collecting station to a storage center and consists of three sections. The first and third sections are above ground and are in contact with the external environment. The intermediate section is sitting on the river bed and is the critical part of the pipeline, once high heat losses are observed. The influence on the type of pipe insulation in the pressure and temperature gradients was analyzed with the aid of commercial 1D software Pipesim®. The results, of this 1D and non-isothermal problem with prescribed outlet pressure, show that the use of isolation when appropriately designed in terms of material quality and thickness is of utmost importance to maintain the heat transfer at low levels, in order to ensure the movement of fluids in long sections without compromising the system operation.</p>