Alkinani, Husam H. (Missouri University of Science and Technology) | Al-Hameedi, Abo Taleb T. (Missouri University of Science and Technology) | Dunn-Norman, Shari (Missouri University of Science and Technology) | Al-Alwani, Mustafa A. (Missouri University of Science and Technology) | Lian, David (Missouri University of Science and Technology) | Al-Bazzaz, Waleed H. (Kuwait Institute For Scientific Research)
It is not easy to obtain an optimal hole cleaning for the drilling operation because of the complicated relationship between the drilling parameters influencing hole cleaning. The two viscosity components (e.g. plastic viscosity (PV) and yield point (YP)) and the flow rate (Q) are essential parameters for effective hole cleaning. Thus, understanding the relationship between those parameters will contribute to efficient hole cleaning. The aim of this paper is to explore those relationships to provide optimal hole cleaning.
Descriptive data analytics was conducted for data of more than 2000 wells drilled in Southern Iraq. The data were first cleansed and outliers were removed using visual inspection and box plots. The Pearson correlation (PC), a widely used method to measure the linear relationship between two parameters, was utilized to access the relationships between PV and Q, YP and Q, and YP/PV and Q. Moreover, a 10% sensitivity analysis was escorted to quantify and comprehend those relationships.
The PCs were calculated to be 0.5, 0.076, and 0.22 for the relationships between YP, PV, and YP/PV with Q, respectively. YP had the highest direct relationship with Q, while PV had the lowest. When the YP increases, a sufficient Q has to be provided to initiate the flow and maintain the mud cycle. In addition, to prevent large solid particles from settling due to the slip velocity, sufficient annular and particle velocities have to be achieved. After initiating the flow, an increase in flow rate to overcome resistance due to PV will not be significant. Therefore, YP has more effect on Q than PV. To maximize hole cleaning, thickening ratio (YP/PV) should be increased. This requires an increase in flow rate, which can be quantified by using the sensitivity analysis provided to achieve the required Q for any increase in YP/PV.
Al-Hameedi, Abo Taleb T. (Missouri University of Science and Technology) | Alkinani, Husam H. (Missouri University of Science and Technology) | Dunn-Norman, Shari (Missouri University of Science and Technology) | Al-Alwani, Mustafa A. (Missouri University of Science and Technology) | Lian, David (Missouri University of Science and Technology)
Flow rate (Q) affects many drilling operations and parameters such as equivalent circulation density (ECD), hoisting and lowering the drillstring, and breaking gel strength during circulation. The aim of this work is to understand the relationship between ECD and Q based on flow regimes (e.g. laminar, transitional, and turbulent) to avoid or at least minimize the unwanted consequence during drilling practice.
Field data from over 2000 wells drilled in Iraq were collected and analyzed to identify the physical relationship between flow regimes and ECD to enhance the drilling rates. After visualizing the whole dataset, a decision was made to break down the data into three parts based on flow regimes (e.g. laminar, transitional, and turbulent). Descriptive data mining techniques were utilized to establish the relationship between flow regimes and ECD. By achieving better control of ECD in the well, not only faster and cheaper operations are possible, but also safety will be improved.
Previous studies and literature showed that flow regimes can tremendously affect ECD. Many studies have been conducted to understand the relationship between Q and ECD. Nevertheless, the consideration of flow regimes was not implemented in these studies. Inconsistency in the literature results was identified, some concluded the relationship between Q and ECD to be direct, and others showed it to be inverse. Thus, this paper will eliminate this discrepancy in the literature, and it will show that the flow regimes have a pivotal role in the relationship between Q and ECD.
The results of this paper showed that if the flow regime is laminar, the relationship between ECD and Q is inverse. However, in transitional and turbulent flow regimes, the relationship between ECD and Q is direct. That is because, in the laminar flow regime, the cutting will fall out of suspension due to low Q, which will cause a cutting bed to be built and decreases ECD. As Q increases (entering the transitional and turbulent flows) the cutting bed will be eroded, and most of the cuttings will be suspended in the fluid which will increase ECD.
This study examines and expands the understanding between how the characteristics of flow regimes affect ECD. Additionally, this paper will eliminate the discrepancy in the literature about this relationship between ECD and Q.
Borehole measurements are often subject to uncertainty resulting from the effects of mud-filtrate invasion. Accurate interpretation of these measurements relies on properly understanding and incorporating mud-filtrate invasion effects in the calculation of petrophysical properties. Although attempts to experimentally investigate mud-filtrate invasion and mudcake deposition have been numerous, the majority of published laboratory data are from experiments performed using linear rather than radial geometry, homogeneous rock properties, and water-based (WBM) rather than oil- or synthetic oil-based drilling mud (OBM or SOBM).
We introduce a new experimental method to accurately reproduce conditions in the borehole and near-wellbore region during, and shortly after the drilling process, when the majority of wellbore measurements are acquired. Rather than using a linear-flow apparatus, the experiments are performed using cylindrical rock cores with a hole drilled axially through the center. Radial mud-filtrate invasion takes place while injecting pressurized drilling mud into the hole at the center of the core while the outside of the core is maintained at a lower pressure. During the experiments, the core sample is rapidly and repeatedly scanned using high-resolution X-ray microcomputed tomography (micro-CT), allowing for visualization and quantification of the time-space distribution of mud filtrate and mudcake thickness. Because of the size of the core sample, the developed experimental method allows for accurate evaluation of the influence of various rock properties, such as the presence of spatial heterogeneity and fluid properties, including WBM versus OBM, on the processes of mud-filtrate invasion and mudcake deposition. Results indicate that our experimental procedure reliably captures the interplay between the spatial distributions of fluid properties and rock heterogeneities during the process of mud-filtrate invasion.
The solid skeleton of the mudcake consists of fine-grain particles; therefore, a mudcake plug is expected to have a very low permeability and a very good ability to isolate the fracture from wellbore pressure. This requires a relatively permeable formation for two reasons: Mudcake buildup requires fluid loss into the formation, and fracture pressure needs to dissipate after being isolated from the wellbore (Kumar et al. 2010).
Using a single universal spacer surfactant to clean a wide variety of oil-based mud (OBM) is considered the "Holy Grail" of spacer fluid system. Specialty chemical and service companies have devoted intense research and vast resources to develop the ideal spacer surfactant, but their efforts have not led to a singlesurfactant solution due to uniquely different drilling mud properties. It is no surprise to experts in the field that surfactant selection is extremely mud specific. For instance, one surfactant may effectively clean certain types of OBM, but fail in another mud from a different location that has the same density and base fluid. As a result, service companies have numerous surfactants in their portfolios, further complicating logistics and operations. This paper presents the discovery of a high-performance universal biomicromaterial, which can significantly improve the cleaning performance of any surfactants/spacer fluids to remove most, if not, all types of drilling mud. The innovative bio-micromaterial is an eco-friendly byproduct from another industry.
Successful cleaning of the drilling mud was demonstrated by standard rotor testing with different OBM samples from across North America, and the percentage of mud removal was determined. Furthermore, the ability of the innovative micromaterial to efficiently clean the mud was verified by measuring the strength of bonding between the set cement and the metal casing that had been cleaned by the spacer fluid after drilling mud contamination. Basically, this new procedure simulates downhole fluid displacement by the intermediate spacer fluid, which is ahead of the cement slurry, displacing the mud. Stability and mixability were also studied to determine the effect of the bio-micromaterial addition to the spacer fluid. Finally, a fundamental scientific study using thermogravimetric analysis and imaging techniques was done to characterize the material and determine its thermal stability.
For the first time, newly discovered, high-performance, universal cleaning micromaterial is presented to enhance the OBM removal of any spacer fluid design. This groundbreaking research has successfully demonstrated the unconventional advanced material to be a universal cleaning, single-additive spacer admixture for a wide variety of drilling mud from various regions across North America. To our knowledge, based on extensive literature search, this is the first report about the application of this natural waste product in wellbore cleaning fluids like the spacer.
Piazza, Ralph (Petrobras) | Vieira, Alexandre (Petrobras) | Sacorague, Luiz Alexandre (Petrobras) | Jones, Christopher (Halliburton) | Dai, Bin (Halliburton) | Price, Jimmy (Halliburton) | Pearl, Megan (Halliburton) | Aguiar, Helen (Halliburton)
This paper presents a new optical sensor configuration using a multivariate optical computation (MOC) platform in order to enhance chemical analysis during formation tester logging operations. The platform allows access up to the mid-infrared (λ ~ 3.5 microns) optical region, which has previously not been accessible for in-situ real-time chemical measurements in a petroleum well environment. The new technique has been used in the field for the analysis of carbon dioxide and synthetic drilling fluid components such as olefins.
MOC is a technique that uses an integrated computational sensor to perform an analog dot product regression calculation on spectroscopic data, optically, rather than by electronic digital means. Historically, a dot product regression applied to spectroscopic data requires both a spectrometer and a digital computer in order to perform a chemical analysis. MOC sensors require neither and because the key sensor component, the multivariate optical element (MOE), is a stable temperature robust solid-state element, the technique is well suited for downhole petroleum environments. A new dual-core configuration using two MOEs designed to work in parallel enhances the sensitivity of the measurement enabling a mid-infrared analysis.
Spectroscopic measurements were performed on 32 base oils that were reconstituted to reservoir compositions over a wide temperature and pressure range up to 350°F and 20,000 psi for a total of 12 combinations for each base oil. Live gas compositions (i.e. reservoir conditions) were achieved by adding multiple methane, ethane, propane, and carbon dioxide charges to each base fluid. The reconstituted petroleum fluids were further mixed with olefin-based synthetic drilling fluid (SDF). This rigorous experimental design data therefore allowed for solid state MOEs to be designed to operate under the same reservoir conditions. Laboratory validation showed measurement accuracy of +/-0.43 wt% for a range of 0 to 16 wt% CO2 and +/-0.4% from 0 to 10 wt% SDF. A wireline formation tester optical section was modified with the MOC dual-core configuration to enable the mid infrared detection of both carbon dioxide and olefins. This formation tester was then deployed in five wells collecting seven samples from various locations. The downhole SDF and carbon dioxide measurements were subsequently found to be in good agreement with laboratory analysis with field results for valid pumpouts showing an accuracy of 0.5 wt% CO2 and 1.0 wt% olefins cross a range of 1.2 to 22 wt% CO2 and 1.4 to 9.7 wt% SDF.
Carbon dioxide is an important component of petroleum whose presence and concentration affects completion options, surface facilities, and flow assurance, which thereby affects operational costs of petroleum production. Olefins are a primary component of synthetic drilling fluid (SDF), although other mid-infrared active components such as esters, ketones, alcohols, and amines also can be present. High concentrations of SDF in openhole formation tester samples lower the quality of laboratory phase behavior analysis and thereby force greater monetary risk in development of assets, especially when conducting reservoir production simulations. Therefore, it is important to monitor both components during formation tester sampling operations.
Eustes III, Alfred W. (Colorado School of Mines) | McKenna, Kirtland I. (Colorado School of Mines) | Zody, Zach J. (Colorado School of Mines) | Healy, Carl (Colorado School of Mines) | Lang, Camden (XTO) | Joshi, Deep (Colorado School of Mines) | Yow, Stephen (Chevron) | McGowen, Kyle (Shell)
Drilling education must evolve continuously to keep up with the changes in the drilling industry. Part of that evolution includes the addition of data analytics in drilling operations. In addition, having a "hands on" experience of actual drilling operations is an important part of the drilling engineering educational process. At the Colorado School of Mines, both goals are achieved using a new coring rig equipped with a high-frequency data acquisition system.
A Sandvik DE 130 Diamond Coring Rig was acquired by the school through a grant from Apache Corporation that has proven to be an excellent analog to full-scale petroleum rigs. It has all drilling subsystems such as rotary, hoisting, power, and circulation. A data acquisition system has been added that tracks accelerations as well as various drilling operational parameters. During experiments, each student has an opportunity to operate the driller's controls and experience the complexities associated with drilling operations including the occasional error. The retrieved core helps the student correlate the formation with drilling data.
The inclusion of the drilling experience in the curriculum has benefited the students in several aspects. This experience has helped students visualize drilling operations and understand complexities and challenges associated with drilling. During the drilling operations, if any problems arise, the students have a chance to troubleshoot those problems in real-time and apply their theoretical knowledge. Operational safety and stop work authority are also a focus and demonstrated by students. This is likely to be the first experience most students have with high-frequency drilling data analysis. Monitoring, collecting, and handling real high-volume data gives a first glimpse into the complexities of data analytics. Noisy realtime data and errors are real and observed by the students. They also learn to handle and analyze high- frequency drilling data identifying normal trends and abnormalities. This coring rig has enhanced the drilling engineering education and data analysis skills of our students.
This work outlines a novel teaching methodology that combines the practical understanding of drilling and the application of data analytics. Getting out to the field and actually drilling rock has enhanced our drilling curriculum to align it with the latest industry practice and to educate future drilling engineers.
A mathematical model is developed to capture the dynamic features in the wellbore during drilling operations so that it could be used for real-time computations. The model comprises one-dimensional (1D) mud flow solvers, one for the drillpipe and the other for the wellbore annulus including the volume below the drill bit, integrated point models for the bell nipple, bottomhole assembly (BHA) nozzles, 1D shallow water model for the flowline, and point model for the bypass replicating the hydraulic circuit in the drilling rig. The model assumes compressibility of mud for the wellbore section along with its transient gel characteristics. The equations are solved using appropriate explicit numerical solvers and the results capturing the fast transients of the standpipe pressure, bottomhole equivalent circulating density (ECD), and the flow rates during dynamic drilling operations are presented to illustrate the performance of the model with field data.
An experimental study was conducted to measure the settling velocity of spherical particles in viscoplastic fluids. Using a mechanistic model based on the balance of the forces acting on the settling particle and detailed statistical analyses of the experimental results, a generalized model for predicting settling velocity of spherical particles in viscoplastic fluids was developed. The main objectives of the study were: i.) To measure the terminal settling velocity of particles in various viscoplastic fluids intending to expand the present database of experimental data ii.) To develop a new Drag coefficient-particle Reynolds number (CD-Rep) correlation that is applicable to both Newtonian and non-Newtonian viscoplastic fluids iii.) To present a general non-iterative approach for predicting settling velocities of particles in Newtonian and non-Newtonian viscoplastic fluids irrespective of their rheological models (Casson Model, Herschel Bulkley Model, and Bingham Model etc.).
The settling velocities of the spherical particles (Specific gravity ranging from 2.5 - 7.7; Diameters: ranging from 1.09 - 4.00 mm) in various Carbopol solutions were measured using Particle Image Shadowgraphy (PIS). The experimental results were combined with experimental data published in the literature to broaden the range and applicability of empirical analysis. Advanced statistical analysis programs (OriginPro 9.0 and MATLAB r2018b) were utilized together with extensive experimental data to develop a new CD-Rep correlation. In this study, a new modified shear Reynolds number (
We have shown that presented new model predicts settling velocity better and yielded relatively more accurate results than existing models with the lowest approximate Mean Absolute Error (MAE) of 0.1 m/s for all data points. In addition to enhanced prediction accuracy, this new model occludes application constraints and offers prediction versatility that is lacking in current existing models by being valid for diverse rheological models of non-Newtonian viscoplastic fluids. The paper is concluded by presenting an illustrative and pragmatic example to calculate the terminal velocity of a spherical particle in a non-Newtonian viscoplastic fluid using the presented generalized model.
The knowledge of particle settling velocity in viscoplastic fluids is indispensable for the design, analysis, and optimization of a wide spectrum of industrial processes such as cuttings transport in oil and gas well drilling and proppant transport in hydraulic fracturing operations. By augmenting the current corpus of experimental data; we have provided much-needed particle settling velocity database that can be used for modeling of relevant transport processes (i.e. cuttings and/or proppants transport). Finally, by combining a mechanistic model describing the forces acting on the settling particles with the newly developed CD-Rep correlation, we have presented a new generalized predictive model of particle settling velocity in viscoplastic fluids that can be used for the optimization of particle transport in oil and gas well drilling and hydraulic fracturing operations.
Successfully spotting an Off-Bottom Cement Plug (OBCP) has been problematic in the oilfield for decades. The use of high viscosity support spacers below the cement plug has been an attractive method to support the cement. These isolation spacers have traditionally been formulated with either biopolymers or bentonitic clays, but they too often fail to support the cement plug due to inadequate viscosity or poor placement. The result is that the cement slumps below the desired location in the wellbore, requiring some remedial action such as spotting an additional spacer and OBCP. One response to this challenge has been the use of a packer to support the plug, but this entails the additional cost of the packer plus the rig time required to place it. A better method was needed to increase OBCP success while reducing costs. A new isolation spacer technology was adapted to meet this challenge, and the resulting field applications are described in this paper. Developmental lab testing will be detailed along with an initial trial well where the spacer was used to isolate a retrievable packer from workover debris. After success there, the same spacer technology was used to successfully support an OBCP on a rigless well abandonment.