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When drilling challenging formations such as very thick highly fractured sour reservoirs or carbonate/karst formations, a lost-circulation zone can be encountered. This causes mud to be lost and gas kick to take place, making the drilling process uncontrollable. Blocking or plugging wide fractures is impossible in many cases, which results in severe safety issues associated with toxic gases.
This study investigates an application of mud cap drilling by injecting foam mixture into the annulus for well control in such harsh conditions. An annular fluid column with foam mixture can be used to prevent kicks and push the toxic gas back into the formation down along the annulus. This foam-assisted mud cap drilling process has been proved to reduce non-productive time and fluid expenses.
This study presents how to model and simulate the process with accurate foam characteristics when foams are used to suppress gas kicks under certain well and fluid conditions. More specifically, this study deals with three scenarios: Base Scenario with a relatively short response time such that the injected foams do not contact the formation gas, and Scenario 1 and 2 with a relatively long response time such that the injected foams interact with the gas, with and without foam coalescence respectively, at the foam/gas interface. The results show how mud-cap drilling parameters (such as pressure, foam density (or, equivalent mud weight), foam velocity, and foam quality) change at different operating conditions and scenarios. Non-Newtonian foam rheology, depending on bubble size and bubble size distribution as modeled by
Gu, Qifan (The University of Texas at Austin) | Fallah, AmirHossein (The University of Texas at Austin) | Gul, Sercan (The University of Texas at Austin) | Ashok, Pradeepkumar (The University of Texas at Austin) | Chen, Dongmei (The University of Texas at Austin) | van Oort, Eric (The University of Texas at Austin) | Moore, Dennis (Marathon Oil Corporation)
Non-aqueous drilling fluids used in deepwater drilling operations are conducive to the dissolution of formation gas during wellbore influx events, increasing the risk of gas kicks going unnoticed. This can lead to hazardous riser gas unloading events if kicks are allowed to pass the subsea BOPs and come out of solution at the bubble point at shallow riser depth. One possible solution to handle and even prevent these events is to generate enough backpressure using Managed Pressure Drilling (MPD) with a Rotating Control Device (RCD) to keep the dissolved gas in solution. However, for large kicks, the required backpressure may exceed riser pressure limits.
A novel kick handling procedure using a dilution control strategy (DCS) is proposed here to handle gas influxes and subsequent gas unloading events. The idea behind this DCS is to inject mud into the riser through the boost line while simultaneously slowing down the circulation rate through the drillstring as the dissolved kick passes the open subsea BOPs. The kick will then get diluted and will be distributed across a larger annular space leading to a significantly decreased gas concentration that can be more easily handled by the MPD system with lower backpressure.
The feasibility of the DCS is investigated in this paper using a multi-phase flow model which is validated against experimental data for a gas kick in oil-based mud. Simulation results for a demonstration case show that a kick entering the well at 18,500 ft with 2,250 kg gas can be thoroughly eliminated with a 3:1 dilution ratio (which is the ratio of riser boost rate to drillstring circulation rate) with approximately 620 psi backpressure when using an MPD system. To improve the applicability of the proposed DCS procedure in field practice, a data-driven approach is implemented using simulated data points to provide a fast estimation of the optimum dilution ratio (DR) to control the kick in real-time.
Noviaris, Ahmad Burhan (PT Pertamina EP) | Syarif, Mustafa (PT Pertamina EP) | Murdiansyah, Warnandes Ambar (PT Pertamina EP) | Pramono, Reza Yudha (PT Pertamina EP) | Nugroho, Sapto Edi (PT Pertamina EP)
Pertamina EP with North Kedung Tuban structure is located in East Java Indonesia. The drilling target is to produce gas from "Kujung" carbonate formation. The characteristic of this carbonate are vugular rock which caused total loss circulation, contain high concentration H2S and 20% CO2. Conventional curing loss methods such pump Lost Circulation Material (LCM) with various type, carbonate cementing and blind drilling, were not the good option since after loss circulation occur, gas kick immediately come up.
To encounter this situation, Floating Mud Cap Drilling (FMCD) technique with sandwich system was applied. This method used Rotating Control Device (RCD) as surface barrier and multiple treating line tied to the annulus casing valve to pump down sandwich. While blind drilling performed, water pumped down through drill string and sandwich system fluid pumped through annulus. Sandwich is a combination of water + kill mud + water and so on. Volume, Kill Mud Weight and time delay for pumping were obtained from previous well data and observations until effective parameters were obtained during blind drilling.
Sandwich fluid purposed as hydro static barrier to overcome gas influx come up to surface during blind drilling. To help good hole cleaning, high viscosity mud pumped frequently through drill string. When TD reached, sandwich system continue applied until BHA pulled inside casing. To accommodate tripping inside casing, change of RCD rubber element and RIH completion string, Downhole Casing Valve is attached in previous casing as mechanical barrier. As a result, the well completed with no gas kick occur while blind drilling and completion string placed as purposed accordingly. Furthermore, good communication between all personnel involved are necessary.
This paper contains the Lesson Learned of FMCD application which is effective and efficient proven in NKT-001 and NKT-001TW well, with the drilling time and cost of hole section 8-1/2" 80% lower than conventional methods.
The current presentation date and time shown is a TENTATIVE schedule. The final/confirmed presentation schedule will be notified/available middle of October 2019. If we have learned anything from the North American experience, unconventional resources cannot be exploited by small incremental projects. If we are to be successful in developing these types of reservoirs, we have to make project scale operations work to bring these resources to market in a timely manner. A number of Eastern Hemisphere unconventional gas projects have raised interest, neared completion or are commencing deliveries.
David Semwogerere holds a BSc in electrical engineering (honors, 2012) from Makerere University in Uganda. In 2012, he started work as a junior well testing and completions engineer at Total. His work involved well test design and execution and working with well engineering modeling and drilling parameter software. He was also a nightshift well test supervisor for Total in the upper west Nile exploration and appraisal campaign on four workover rigs. Semwogerere later moved to the China National Offshore Oil Company in 2014 as a well completion engineer in the Kingfisher Albertine exploration region on Lake Albert.
Temitope Ajayi is a full time Graduate Student/Researcher at the Craft and Hawkins Department of Petroleum Engineering, Louisiana State University, Baton Rouge USA. He was born in Lagos, Nigeria where he studied for a bachelor's degree in Petroleum Engineering at the University of Lagos. Thereafter, he earned a master's degree in Petroleum Engineering at the Petroleum Institute (now Khalifa University of Science and Technology), United Arab Emirates (UAE). He has been an active member of SPE since 2014 and has served in various capacities in the student chapters of the institutions he has attended. He has research interests in a broad range of technical topics and has worked on topics ranging from carbon dioxide storage, enhanced oil recovery, reservoir simulation and well integrity.
Decisions in E&P ventures are affected by Bias, Blindness, and Illusions (BBI) which permeate our analyses, interpretations and decisions. This one-day course examines the influence of these cognitive pitfalls and presents techniques that can be used to mitigate their impact. Bias refers to errors in thinking whereby interpretations and judgments are drawn in an illogical fashion. Blindness is the condition where we fail to see an unexpected event in plain sight. Illusions refer to misleading beliefs based on a false impression of reality. All three can lead to poor decisions regarding which work to undertake, what issues to focus on, and whether to forge ahead or walk away from a project. Strategic thinking and planning are key elements in an organisation’s journey to maximise value to shareholders, customers, and employees. Through this workshop, attendees will go through the different processes involved in strategic planning including the elements of organisational SWOT, business scenario and options development, elaboration of strategic options and communication to stakeholders. Examples are provided including corporate, business unit and department case studies. This seminar will teach participants how to identify, evaluate, and quantify risk and uncertainty in everyday oil and gas economic situations. It reviews the development of pragmatic tools, methods, and understandings for professionals that are applicable to companies of all sizes. The seminar also briefly reviews statistics, the relationship between risk and return, and hedging and future markets.
SPE, through its Energy4me programme, will present a free one-day energy education workshop for science teachers (grades 8–12). A variety of free instructional materials will be available to take back to the classroom. Educators will receive comprehensive, objective information about the scientific concepts of energy and its importance while discovering the world of oil and natural gas exploration and production. Energy4me is an energy educational public outreach programme that highlights how energy works in our everyday lives and promote information about career opportunities in petroleum engineering and the upstream professions. SPE’s Energy4me programme values the role teachers and energy professionals play in educating young people about the importance of energy.