Multiphase flow can be present in all aspects of underbalanced drilling. This paper outlines the ways in which multiphase flow pressure loss calculations can be used by drilling engineers in the design and optimization of underbalanced drilling operations. Then, detailed field measurements for several horizontal wells drilled underbalanced with coiled tubing are used to evaluate the application of existing pressure loss calculation methods to this unique application. Introduction Underbalanced drilling (UBD) is rapidly gaining popularity in the oil and gas industry. The Alberta Energy and Utilities Board ID94–3(1) defines underbalanced drilling as follows: "When the hydrostatic head of a drilling fluid is intentionally designed to be lower than the pressure of the formation being drilled, the operation will be considered underbalanced drilling. The hydrostatic head of the drilling fluid may be naturally less than the formation pressure or it can be induced. The induced state may be created by adding natural gas, nitrogen, or air to the liquid phase of the drilling fluid. Whether induced or natural, this may result in an influx of formation fluid which must be circulated from the well and controlled at surface." Benefits of Underbalanced Drilling Maintaining the pressure in the wellbore below the reservoir pressure allows reservoir fluids to enter the wellbore while UBD operations proceed, thus preventing flow of drilling fluids (and associated solids) into the formation, thereby minimizing or even eliminating formation damage. This is of particular importance in the drilling of horizontal wells as the formation is exposed to the drilling fluids for an extended period of time. Although formation damage reduction is the most widely recognized benefit of underbalanced drilling, several additional benefits are outlined below: Increased Penetration Rates Underbalanced drilling can achieve higher rates of penetration due to reduced "chip holdown" and decreased hydrostatic pressure at the bit face. Reduction in "chip holdown" refers to easier removal of drilled solids from the vicinity of the drill bit due to the flow of drilling and reservoir fluids, thus allowing the bit to drill into fresh rock continuously. The decreased hydrostatic pressure at the bit face reduces stress in the rock being drilled, allowing it to fail more easily. The experience of drilling engineers(2) familiar with UBD is that the rate of penetration can be increased by between three and ten times that of conventional drilling. Minimal Lost Circulation Underbalanced drilling gives better control in situations where fractured, low pressure, or high permeability formations may lead to the loss of drilling fluids and the associated problems that can cause. Evaluation While Drilling Data acquired in real time during underbalanced drilling operations allow for both the short term on site optimization of the UBD operation, and the longer term assessment of the well's potential. On site, the data acquired can be used to optimize drilling parameters such as the well's horizontal length, vertical depth, and orientation. Other data that can be obtained, useful both on site and long term, include fluid properties, productivity, and geological interpretations of the formation.
TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractStuck pipe incidents are one of the major operational challenges of the E&P industry and events usually lead to significant amount of lost time and associated costs. Various industry estimates claim that stuck pipe costs may exceed several hundred million US dollars per year. In Saudi Aramco, the recent increase in drilling activity, drilling in depleted and higher-risk reservoirs have led to an increased risk of stuck pipe. In 2010 Saudi Aramco formed a task force to focus on lowering its stuck pipe costs. In its campaign to reduce this cost, the task force selected key personnel from each of the Drilling & Workover (D&WO) operating departments.This paper summarizes the result of the Stuck Pipe Teams' findings and the best practice documents generated. For 2009, 69.5% of the total stuck pipes were due to mechanical sticking and 30.5% attributed to differential sticking. Furthermore, based on the team's findings, a customized training plan was formulated to certify key D&WO operations personnel every 2 years.
TX 75083-3836 U.S.A., fax 1.972.952.9435. AbstractSaudi Aramco planned to drill three horizontal wells underbalanced in the Uthmaniyah Field in Saudi Arabia but concern was raised because the large volume of fluid produced would also contain a high concentration of H 2 S. A detailed engineering study was conducted of the well parameters and it was recommended that a diesel-based fluid system be used initially for compatibility, cuttings carrying capacity and pressure control. Since the underbalanced operation was based on the flow drilling technique, the drilling fluid system was diluted and became a produced oil system as the underbalanced drilling operation progressed.An important part of the design and treatment program was the minimization of H 2 S exposure for personnel on the rig site. A preliminary review of the operation revealed the areas of greatest concern; and the equipment layout was designed to ensure efficient separation and permit fluid treatment at surface. Laboratory studies recommended a proprietary oilsoluble H 2 S scavenger to remove residual H 2 S in the circulating fluid, and treatment points were selected for optimal performance.All three wells were successfully drilled in an underbalanced condition. There were some minor H 2 S releases on the first well at several open points in the system, requiring a reassessment of the separation layout and design, particularly in the solids control equipment, and in the fluid treatment program.Once this was accomplished, the subsequent wells proceeded more smoothly. H 2 S levels in both the liquid and gas streams were monitored and showed very good removal efficiency despite the high production of both oil and gas from the wells. This paper describes the design of the fluid system and separation equipment for the three wells. It will also highlight results from all three wells, showing the learning experience and optimization of the drilling operation from a fluid engineering and treatment point of view, as well as recommendations for future wells.
With the increased environmental awareness about Naturally Occurring Radioactive Material (NORM), many companies are adopting policies to address the exposure and contamination issues associated with this material. In developing and implementing a NORM policy, every aspect of one's business must be thoroughly evaluated to determine at what point this material is encountered and what processes tend to concentrate this material. Once all areas having elevated levels of NORM or the potential for such are identified, then the intrarelationships between these areas must be evaluated. After identifying all possible problem areas, then the evaluation, interpretation, and clarification of existing and proposed regulations must begin.Locations and operations within a single country must be evaluated with respect to that country's regulations and in light of any other country's regulations which may affect their activities once outside of that country. The main areas evaluated were: employee exposure, environmental contamination, facility and equipment contamination, logistics of moving between facilities covered by different regulations, existing and proposed regulations, trends of proposed regulations, disposal of NORM, transportation of NORM, training, and survey equipment.In the final analysis, the corporate NORM policy should incorporate all the main areas _ discussed and implementation should integrate these areas into each component of the organization with standardization. BV doing so, the corporate NORM program provides the stability and means for accurate, reproducible data, yet allowing the program the flexibility to address new and proposed regulations and subsequent requirements. INTRODUCTION Radioactivity associated with nuclear power and nuclear weapons has received a lot of recognition and press. A lot more common and a lot less publicized type of radioactive material is Naturally Occurring Radioactive Material
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.
hi@scite.ai
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.