V. Kelessidis | Texas A&M University at Qatar (original) (raw)

Papers by V. Kelessidis

Volume 8: Polar and Arctic Sciences and Technology; Petroleum Technology, 2017

Accurate pressure drop estimation is vital in the hydraulic design of annular drillholes in Petro... more Accurate pressure drop estimation is vital in the hydraulic design of annular drillholes in Petroleum Industry. The present study investigates the effects of fluid velocity, fluid type, fluid rheology, drillpipe rotation speed, drillpipe eccentricity and drillhole inclinationon on pressure losses with the presence of cuttings using both experiments and computational fluid dynamics (CFD). The eccentricity of the drillpipe is varied in the range of 0 – 100% and it rotates about its own axis at 0 – 150 rpm. The diameter ratio of the simulated drillhole is 0.56 and it is inclined in the range of 0 – 15°. The effects of fluid rheology are addressed by testing power law and yield power law fluids. Both of the laminar and turbulent conditions are experimentally tested and numerically simulated. Experimental data confirmed the validity of current CFD model developed using ANSYS 16.2 platform. The goal of the current work is to develop a comprehensive CFD tool that can be used for modeling t...

The continuous and ever increasing demand for fossil fuels and in particular oil and gas has push... more The continuous and ever increasing demand for fossil fuels and in particular oil and gas has pushed drilling and exploration industry to drill in ultra deep waters (water depths more than 2000 m) with the wells drilled to depths in excess of more than 7500 m. These wells are very expensive to drill and complete with costs up to about $100 million. Reservoir challenges are pore pressures that exceed 138 MPa beyond the limit of some current logging tools while the temperatures are not as extreme being around 125 C. In this paper we examine the challenges placed on drilling equipment, critically review the state of the art on developing new tools and techniques to withstand these high pressures and present views about the potential depth limits for hydrocarbon drilling. In addition, techniques and innovative tools to address these challenges are presented. The abiotic theory of hydrocarbon generation from the depths of earth is also reviewed, based on prior and recent research findings...

SPE Drilling Engineering, 1991

Summary Continuous monitoring of hydrocarbon gases in drilling fluids at the surface is essential... more Summary Continuous monitoring of hydrocarbon gases in drilling fluids at the surface is essential for identification of prospective reservoir zones as well as for safety. This paper describes a new gas-analysis system that determines the total amount of gas in this mud below the bell nipple. The system is continuous, consistent, and fully quantitative (unlike a gas trap) but not labor-intensive (like a steam still). It also recovers and analyzes gas liberated into the air at the bell nipple, which test results have shown to be almost 50% of the total gas in the mud below the bell nipple. Introduction J.T. Hayward, the "father of mud logging," once said, .... it is for the fluid contents, rather than for the rock itself, that wells are drilled." That statement still applies today, although mud logging is now viewed as a "low-tech" operation when compared with measurement-while drilling (MWD) and wireline techniques. Conventional mud logging has been around fo...

SPE Advanced Technology Series, 1996

Downhole zonal isolation requires the efficient removal of mud from the annulus and its replaceme... more Downhole zonal isolation requires the efficient removal of mud from the annulus and its replacement by competent cement. While good cementing practices have been developed over the years the results are not always satisfactory mainly because the techniques for mud removal are not optimized. Improved mud removal techniques have recently been developed which take into account quantitatively most of the parameters affecting mud displacement and cement placement. Application of these techniques has lead to considerable successes in the field. This paper provides further evidence of the effectiveness of these techniques by presenting the results of a field campaign. Introduction The main objective during primary cementing is to achieve downhole zonal isolation. This requires that the drilling fluid in the annulus be completely replaced by the cement slurry. Incomplete mud displacement can leave a continuous mud channel across the zones of interest thus favoring interzonal communication. ...

Proceedings of European Formation Damage Conference, 2007

This paper describes first results of an extensive laboratory research program aiming at identify... more This paper describes first results of an extensive laboratory research program aiming at identifying potential additives for bentonite suspensions which would extend their use at high temperatures by maintaining or even improving the rheological and the filtration characteristics of these fluids. Five different Grrek lignites have been tested, at 3% wt. concentration, together with a commercial lignite product, used as reference. API filter press data and rheological data showed that thermal aging of bentonite suspensions results in deterioration of rheological and filtration properties while lignite addition was very beneficial. Static filtrations tests against Berea sandstones have been performed using a core holder and the various mud formulations. Pressure ports along the core holder allowed determination of permeability evolution during testing of the formed cake as well as of the core itself. A backflash arrangement allowed for determination of permeability recovery. Thermally aged muds reduced significantly core permeability and gave recovery rates around 50%. Three of the lignite samples, have maintained original core permeability giving also very high recovery rates. Some of the lignite samples, including the commercial one, did not perform as well and also gave permeability recoveries between 10 to 80%. Thus, static filtration against cores allows for differentiation of well performing lignite samples not only in API filter press tests but also in core permeability experiments.

Coiled Tubing Drilling (CTD) has grown significantly in recent years as a niche market for drilli... more Coiled Tubing Drilling (CTD) has grown significantly in recent years as a niche market for drilling jobs considered not good candidates for conventional rotary drilling due primarily to high cost associated with them. CTD is normally associated with high angle to horizontal and extended reach wells. It is, however, in these applications that hole problems, due to inefficient cuttings removal, become more troublesome. These problems are enhanced due to the non rotation of the inner string (the CT itself) as opposed to normal (or conventional) drilling where the inner pipe rotation imparts some motion and agitation of the drilled solids thus minimizing hole problems due to cuttings accumulation. Many parameters affect efficient cuttings transport in Coil Tubing Drilling in horizontal and deviated geometries. Among these are pump rates, well dimensions, fluid properties, solids sizes and solids loading. Drilling should be designed and carried out so that all cuttings are maintained in suspension and no cuttings bed is formed. Several attempts have been made to determine the optimum operating range of these parameters but complete and satisfactory models have yet to be developed. The purpose of this paper is to provide a critical review of the state of the art of previous approaches to efficient cuttings transport during Coil Tubing Drilling, present the critical parameters involved and establish their range according to what is observed in practice through dimensional and similarity analysis. Finally the laboratory system that has already been set up is presented. Its primary purpose is to allow the gathering of good quality data, which are really missing from the literature, which could aid into better understanding the flow of solid – liquid mixtures in annul

IADC/SPE Asia Pacific Drilling Technology Conference and Exhibition, 2012

Summarization: Assessment of drilling performance during Casing Drilling and optimization of the ... more Summarization: Assessment of drilling performance during Casing Drilling and optimization of the process has been achieved using an existing computer simulator, which has not been tested before in Casing Drilling applications while its value has been proven in conventional drilling. The simulator allows prediction of ROP using standard drilling data of WOB, RPM, flow rate, and formation parameters. Use of simulator post drilling allows fine tuning it to match drilling performance so that future jobs in the same field could be more optimally designed. Different lithologies along the wellbore were defined in terms the rock type, strength, and abrasivity from drilling data collected while Casing Drilling of a 2000 ft well in Haynesville shale, where ROP was high in the upper part but fairly low in the lower part. Rock strength data normally is not given and estimation was made from databases for similar rocks while they could be estimated from sonic data if available. Running the simulator allows for re-drilling the well utilizing all basic data and trying to match the real drilling time curve and the measured ROP. Good matching was achieved for the drilling depth-time and also ROP values were matched well over the whole depth interval. Using the simulated model, WOB and RPM were optimized to increase the ROP at the lower part of the well. The results proved that the simulator can simulate Casing Drilling effectively as it has proved its value for conventional drilling. This work shows that the simulator can help the driller to use historical data of Casing Drilling and then by applying different scenarios, e.g. increasing WOB or RPM and he can apply them while drilling a new well to obtain higher ROP. Using the simulation results, optimal drilling parameters can thus be found for drilling future wells in similar geologic environments.Παρουσιάστηκε στο: IADC/SPE Asia Pacific Drilling Technology Conference and Exhibitio

SPE Drilling & Completion, 2004

Summary Coiled-tubing drilling (CTD), which has grown significantly in recent years, is normally ... more Summary Coiled-tubing drilling (CTD), which has grown significantly in recent years, is normally associated with high-angle to horizontal and extended-reach wells. In these applications, however, hole problems become more troublesome because of inefficient cuttings removal. Among the many parameters affecting efficient cuttings transport in CTD are pump rates, well dimensions, fluid properties, solid sizes, solid loading, and hole inclination. Several attempts have been made to determine the optimum operating range of these parameters, but complete and satisfactory models have yet to be developed. The purpose of this paper is as follows: To provide a critical review of the state-of-the-art modeling for efficient cuttings transport during CTD. To present the critical parameters involved. To establish their range according to what is observed in practice. To propose a different approach for predicting the minimum suspension velocity. To describe the laboratory system that has been set...

Applied Clay Science, 2007

The effectiveness of lignite addition to prevent gelation of 6.42% w/w waterbentonite suspension... more The effectiveness of lignite addition to prevent gelation of 6.42% w/w waterbentonite suspensions exposed to high temperatures has been studied, using twenty six lignites from various basins in Greece with variable organic and inorganic contents at concentrations of 0.5% and ...

Simulating U-tubing, or fluid free fall, to predict annular flow rates and wellhead pressures can... more Simulating U-tubing, or fluid free fall, to predict annular flow rates and wellhead pressures can improve the design and pumping of primary cement jobs. Proper modeling of U-tubing can help identify potential downhole problems such as formation fracturing leading to lost circulation or inadequate mud removal leading to a poor cement bond. U-tubing is caused by the density difference between

Day 2 Wed, May 26, 2021, 2021

Drilling challenging wells requires a combination of drilling analytics and comprehensive simulat... more Drilling challenging wells requires a combination of drilling analytics and comprehensive simulation to prevent poor drilling performance and avoid drilling issues for the upcoming drilling campaign. This work focuses on the capabilities of a drilling simulator that can simulate the directional drilling process with the use of actual field data for the training of students and professionals. This paper presents the results of simulating both rotating and sliding modes and successfully matching the rate of penetration and the trajectory of an S-type well. Monitored drilling data from the well were used to simulate the drilling process. These included weight on bit, revolutions per minute, flow rate, bit type, inclination and drilling fluid properties. The well was an S-type well with maximum inclination of 16 degrees. There were continuous variations from rotating to sliding mode, and the challenge was approached by classifying drilling data into intervals of 20 feet to obtain an app...

Chinese Journal of Chemical Engineering, 2012

Injection fluids used during oil and gas drilling require specific rheological properties, and a ... more Injection fluids used during oil and gas drilling require specific rheological properties, and a bentonite-based drilling fluid enhanced with iron nanoparticles has been analysed to investigate its suitability for high-performance drilling applications. Accordingly, it is necessary to model the shear stress and viscosity in terms of the fluid shear rate, temperature and concentration of iron nanoparticles (Dandekar, 2013). By developing models relating these variables it is possible to examine how the viscoplastic fluid behaves under different drilling conditions and if it can reliably ensure process performance. Under steady shear, flow behaviour will vary with concentration and temperature (Andertova & Rieger, 2009), and careful tuning of rheological characteristics is critical to the design of the process. The currently prevalent tri-parametric model relating shear stress and shear rate is the Herschel-Bulkley model (Kelessidis et al., 2006; Kelessidis & Maglione, 2008; Pouyafar ...

Applied Clay Science, 2017

The paper reviews the recent exploration activity of hydrocarbons in Greece and neighbouring Alba... more The paper reviews the recent exploration activity of hydrocarbons in Greece and neighbouring Albania and Turkey. Emphasises the relevance of the prospects in these neighbouring countries and those identified in Greece, and finally accentuates the importance of a new exploration strategy in Greece. With only few deep exploration wells drilled the last years, none offshore, the area should be set

Journal of Dispersion Science and Technology, 2013

ABSTRACT