As the demand for natural gas continuously increases to meet electricity production needs, more alternative natural gas sources are usually required to cope with the increased demand in the summer months. In South Iraq, this situation is the main driver for exploiting economically feasible and efficient solutions in finding additional natural gas resources. As a result, the Iraqi government embraces the challenge by drilling deeper formations which are gas bearing, with limited experience in such fields. In the most recent appraisal campaign for these gas fields, performed in 2015 and 2016, one of the main challenges were bits and bottom hole assembly (BHA) failures while drilling through different interbedded and abrasive formations. Changing the bits type, BHA centralization, drive system and drilling parameters did not result in significant benefits. For the 17 ½" section, up to six (6) independent runs were required to successfully drill the entire section. The success was limited due to severe shocks and vibrations, high axial forces and high torque that caused failures on downhole mud motors and bits, leading to fishing operation and severe non-productive time. Other problems like unstable drilling parameters, extremely low rate of penetration (ROP) and poor wellbore quality were observed, leading to excessive reaming and backreaming as well as stuck pipe events and difficulties to maintain well verticality. To avoid and minimize the impact of these challenges, a comprehensive engineering team performed various finite element analysis on the interaction between BHA, drilling bit and formations drilled. The conditions on which the wellbore was maintained in the offset wells with its drilling fluids strategy and drilling parameters were reanalyzed. The bits selections were revised, identifying areas of opportunity to introduce fit for purpose technologies on cutters and bits profile. The ultimate challenge was to drill the full 1800 m of the section in one run avoiding any BHA related failure. The results exceeded expectations in the fourth well, where no BHA related failures were observed, and the drilling bit was able to drill the full 1800 m. Connection practices were also optimized. This enabled an improvement in the wellbore quality based on caliper logs. Improved wellbore conditions allowed a smooth casing run and consecutive cement job. This paper will discuss the engineering methodology followed to achieve this important milestone in one of the few gas fields in Iraq. It will go through the details of the technologies implemented on BHA analysis, bit selection, drilling parameters optimization and drilling fluids strategy implemented. The objective of this paper is to share with the oil and gas industry a methodical approach for efficient drilling, and how to address drilling challenges with technology introduction and engineering design.
Downhole tool failures induced by drill string vibrations was one of the leading causes of non-productive time in a deep exploratory field in southern Iraq. To improve drilling efficiency, it was paramount to understand the primary source of potential drilling dysfunction before commencing field development phase. To overcome the challenge, a finite element analysis (FEA) study was developed to simulate the drillstring transient dynamic behavior from bit back to surface. The model has been utilized to quantify the potential vibration, contact force, torque, displacement and other high-interest parameters of every drillstring component in the wellbore. To fully exploit the modeling algorithms, it is required to input a comprehensive dataset including mechanical rock properties, cutting structure design, bit drive mechanism, drillstring physical characteristics, 3D well profile and expected drilling parameters. Using offset well data, surface and downhole measurements, and a thorough knowledge of drilling equipment, the model creates a virtual drilling environment simulating the downhole drilling conditions enabling the evaluation of the source of inefficiency. Finally, the model is validated for its accuracy by comparing its outcomes with actual field acquired data. By accurately modeling the drillsting interaction with the drilling environment, the operating company was able to evaluate different BHA options to safely drill the wells and by reducing harmful vibrations, minimizing tool failures, increasing ROP, this translates to a reduction of drilling time by 24%. This paper will share with the industry a case study demonstrating the value of the utilization of the advanced dynamic modeling which has been able to save over 500 K$ per well to the operating company by an efficient selection and placement of drill string components. This approach has enabled to outperform past drilling performance and has become the norm in similar fields in southern Iraq.
The Comalcalco Fault is a regional discontinuity that can present highly unstable zones when crossing it or its influence zone. This instability can lead to notorious increase in drag forces, cavings, stuck pipe events and ultimately loss of sections or the well. In the 12 ¼" hole of this exploratory well, this fault was present and despite some of the wells in the field managed to cross it without consequences, the influence was more notorious, and the problems lead to catastrophic results. While drilling the 12 ¼" section, the team was able to drill up to 4368 m without any relevant problems. The fault was intersected and drilled pass to section TD with the previous casing shoe at 2966 m. However, when a trip to surface was necessary, abnormal drag forces that avoided further movement of the string were experienced. This event led to the loss of the section and the need to perform a sidetrack, right across the influence zone of the fault at 3200 m. The risk was reassessed, and numerous preventive and mitigation measures were put in place, including drilling the section with a 12 ¼" pilot bit, enlarging the pilot hole to 13 ½" to cover the influence zone and having a contingency plan to run the 11 ¾" liner. Additionally, the formations were reinforced through drilling fluids design, and drilling and tripping strategies were optimized to minimize zonal invasion and influence zone disturbances that could lead to additional cavings. After the successful sidetrack, the section was drilled to 3600 m, 200 m below the fault’s influence zone. Good ROPs and low levels of stick and slip were observed despite several reaming runs while drilling. The contingency liner was run to TD, achieving the objective of isolating the influence zone of the Comalcalco Fault. With the problematic zone placed behind pipes, drilling the remaining of the original 12 ¼" sections with a 10 5/8" × 12 ¼" reamer resulted in the longest and fastest enlarged section to be realized in the field. With all the preventive measures put in place, the original 9 5/8" casing was set at its planned depth, avoiding an additional casing string and a change of the design of the completion.
Dado que es una necesidad mejorar constantemente la malla vial en la ciudad de Bogotá D.C., así como aprovechar adecuadamente los recursos dispuestos para las vías de carácter local e intermedia, se hace fundamental priorizar en una parte de la infraestructura urbana: la supervisión y mantenimiento detallado de la semaforización, dispositivo que regula el tráfico de vehículos y peatones en las intersecciones de las calles. En este sentido, se caracterizó, identificó y evaluó el despliegue de los contratos interadministrativos que se ejecutan actualmente, mediante visitas de campo que permitieron valorar el estado actual del sistema semafórico, lo que proporcionó una visión holística de su funcionamiento. Lo anterior permitió el planteamiento de alternativas de mejora desde la parte eléctrica, equipos de control, interconexión, postes y obras civiles, para reforzar la conformación del sistema de movilidad según las disposiciones del Plan de Gobierno de Bogotá para el área específica, periodo 2012-2015 y del Plan Maestro de Movilidad para Bogotá Distrito Capital.Motion for diagnosis and management of activities of maintenance system of Bogotá D.C. traffic lightsABSTRACTSince it is a necessity to constantly improve the road network in the city of Bogotá and benefit adequately prepared resources for local roads and intermediate character is therefore essential to prioritize a part of urban infrastructure such as the monitoring and detailed maintenance of traffic lights, device regulating vehicular traffic and pedestrians at intersections of streets. In this sense, was characterized, identified and evaluated the deployment of inter-administrative contracts that are currently running through field visits that allowed assess the current state of the traffic light system, and it provided a holistic view of their performance. This allowed the approach of improvement alternatives from the Electrical hand, control equipment, interconnection, poles and civil works to strengthen the conformation of the mobility system under the provisions of the Plan of Government of Bogotá for the specific area, period 2012- 2015 and Mobility Master Plan for Bogotá Distrito Capital.Keywords: auditing control equipment, electric auditing, mobility, supervision of civil works and posts, traffic lights.
Obtaining a good cement bond is a continuous challenge, especially if the well being cemented is a high-pressure exploration gas well, and it is one of the very few gas wells drilled in the country. Poor adherence to the casing and the formation, channeling due to gas migration and microannulus are some of the main risks that could result in a poor cement job. Achieving zonal isolation and a good cement sheath protecting the 7-inch liner turned out to be an objective missed for the first two wells of the campaign, compromising the long-term supply of gas to the South region of Iraq. To solve the situation, it was necessary to implement something more than a mere cementing additive; it required a multifactor analysis with an experienced multidisciplinary team. A set of good drilling practices, proper drilling fluids, proven cementing techniques and new technology slurries were combined to improve the precious results. To obtain a sound cement quality log, the well engineering department teamed up with cementing experts, drilling fluids specialists, liner hanger company representatives and operations personnel. With effective meetings, proper risk assessment and visible leadership, the team generated a series of initiatives that included: drilling hydraulics optimization, mud weight selection, drilling practices re-definition, liner hanger procedure adjustments and cementing slurry design. As a result, the borehole caliper was significantly improved, the liner hanger allowed full rotation while cementing, cement returns were observed above the liner top after the job, no evidence of gas migration was observed and the CBL-VDL-USIT log showed a remarkable improvement in the two jobs where the engineering initiatives were applied. Being able to achieve a positive proof on cementing integrity, one of the most important acceptance criteria for the National Oil Company (NOC) regulation entity, enhanced the trust on the technical experts of the engineering team to deliver solutions of complex problems.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.