Dashti, Qasem M. (Kuwait Oil Company) | Al-anzi, Ealian H.D. (Kuwait Oil Company) | Al- Doheim, Aref (Kuwait Oil Company) | Kabir, Mir Md Rezaul (Kuwait Oil Company) | Acharya, Mihira Narayan (Kuwait Oil Company) | Al-Ajmi, Saad (Kuwait Oil Company)
Robustness of measurement while drilling (MWD) and logging while drilling (LWD) tools is laboratory-tested and rigorously field-tested for the expected operating and measurement specifications. Such tools have been used in the industry for decades with proven track record of stability. However, a typical tool string deployed as a part of bottom-hole assembly (BHA) has recently failed to withstand the unexpected BH conditions during drilling of the pilot hole using potassium formate mud (KFM), a heavy water based mud. The failure occurred within a deep-fractured calcareous kerogen section (CKS).
The tools had multiple surface communication failures; the first one was resolved as debris was found obstructing the rotor-starter part before drilling the CKS. The second failure occurred in the back-up tools, after drilling into the CKS and remained unexplained throughout drilling with the expectation of BH data recorded on memory. Inspection of the tool components, once the drilling was completed, revealed two major findings: First, some parts of the BHA, specifically the components of the CuBe tool had "vanished??. Secondly, the recovered tool parts had further damage due to corrosion and pitting. In addition, an unexpected color change in metal body parts was observed.
In the paper, the authors explain the unique mystery of tool eating "down-hole ghost??. Similar tools were previously used without an issue at comparable high pressure and temperature conditions and in geological sections alike in Kuwait in drilling with oil-based mud. The service provider's operational experience elsewhere has failed to explain the bizarre outcome, as they had not encountered similar incidents of vanishing tool parts and down-hole color change. The claim was that similar tools were successfully operated in water-based mud drilling including KFM. This claim was confirmed prior to the field execution with metallurgical compatibility tests carried out by the mud supplier.
Ozyurtkan, Mustafa Hakan (Istanbul Technical University) | Altun, Gursat (Istanbul Technical University) | Ettehadi Osgouei, Ali (Istanbul Technical University) | Aydilsiz, Eda (Istanbul Technical University)
Static filtration of drilling fluids has long been recognized as an important parameter for drilling operations. Since the standard laboratory testing procedures only consider static conditions, the filtration and cake properties under continuous circulation and dynamic borehole conditions are not usually well determined. Therefore, the measurement of dynamic filtration is particularly important in order to mimic actual downhole conditions.
An experimental study has been carried out by the ITU/PNGE research group to characterize the dynamic filtration properties of clay based drilling fluids. This study is an impressive attempt to figure out the dynamic filtration phenomena of clay based muds. The experimental results obtained from a dynamic filtration apparatus (Fann Model 90) are reported in this study.
Bentonite and sepiolite clays based muds formulated with commercial additives have been investigated throughout the study. Numerous dynamic filtration histories with test duration of 45 to 60 minutes at temperature conditions ranging from 150 to 400 oF, and a differential pressure of 100 psi have been applied to muds. Three key parameters namely spurt loss volume, dynamic filtration rate (DFR), and cake deposition index (CDI) have been determined to characterize the dynamic filtration properties of mud samples.
Results have revealed that bentonite based muds have better dynamic filtration properties than those of sepiolite muds at temperatures up to 250 oF. However, they have lost their stability over 250 oF. Furthermore, formulated sepiolite based muds have remarkable dynamic filtration rates and cake depositions above 300 oF. To sum up, the experimental results of this study point out that sepiolite based muds might be a good alternative to drill wells experiencing high temperatures, particularly in deep oil, gas and geothermal wells.
At Kuwait Oil Company (KOC) most of the ESP wells are running with downhole sensors to enhance the daily monitoring routine and for having a better knowledge of the pumps performances. However, one of the most important parameter of these ESP Wells is only known after a time period within 3-6 months: The Flow Rate. Production Tests are obtained using Multiphase Flow Testing Units which usually last between 4 and 6 hours that are also utilized to conduct some sensitivities such as choke size and motor speed changes. At Well Surveillance Group, a tailored fit model was developed from which the ESP flow rate can be estimated based on the downhole sensor data and basic fluid properties with an overall deviation below 2% (when they are compared to the results obtained from the Testing Unit). In this sense, flow rate monitoring can be performed at any time and flow testing time and associated cost can be reduced among other benefits. The method requires knowing the ESP model and total number of stages installed in the well, and then using the corresponding performance curve of the ESP model usually provided by the manufacturer, the data is processed and the calculation performed. This work aims to show how this model works, advantages, limitations, implementation status and future improvements.
The significance of exploring deep and ultra-deep wells is increasing rapidly to meet the increased global demands on oil and gas. Drilling at such depth introduces a wide range of difficult challenges and issues. One of the challenges is the negative impact on the drilling fluids rheological properties when exposed to high pressure high temperature (HPHT) conditions and/or becoming contaminated with salts, which are common in deep drilling or in offshore operations.
The drilling engineer must have a good estimate for the values of rheological characteristics of a drilling fluid, such as viscosity, yield point and gel strength, and that is extremely important for a successful drilling operation. In this research work, experiments were conducted on water-based muds with different salinity contents, from ambient conditions up to very elevated pressures and temperatures.
In these experiments, water based drilling fluids containing different types of salt (NaCl and KCl) and at different concentrations were tested by a state-of-the-art high pressure high temperature viscometer. In this paper, the effect of different electrolysis (NaCl and KCl) at elevated pressures (up to 35,000 psi) and elevated temperatures (up to 450 ºF) on the viscosity of water based mud has been presented.
The high-profile blowout at Macondo well in the US Gulf of Mexico, brought the challenges and the risks of drilling into high-pressure, high-temperature (HPHT) fields increasingly into focus. Technology, HSE, new standards, such as new API procedures, and educating the crew seem to be vital in developing HPHT resources. High-pressure high-temperature fields broadly exist in Gulf of Mexico, North Sea, South East Asia, Africa, China and Middle East. Almost a quarter of HPHT operations worldwide is expected to happen in American continent and the majority of that solely in North America. Oil major companies have identified key challenges in HPHT development and production, and service providers have offered insights regarding current or planned technologies to meet these challenges. Drilling into some shale plays such as Haynesville or deep formations and producing oil and gas at HPHT condition, have been crucially challenging. Therefore, companies are compelled to meet or exceed a vast array of environmental, health and safety standards.
This paper, as a simplified summary of the current status of HPHT global market, clarifies the existing technological gaps in the field of HPHT drilling, cementing and completion. It also contains the necessary knowledge that every engineer or geoscientist might need to know about high pressure high temperature wells. This study, not only reviews the reports from the Bureau of Ocean Energy Management, Regulation and Enforcement (BOEMRE) and important case studies of HPHT operations around the globe but also compiles the technical solutions to better maneuver in the HPHT market. Finally, the HPHT related priorities of National Energy Technology Laboratories (NETL), operated by the US Department of Energy (DOE), and DeepStar, as a strong mix of large and mid-size operators are investigated.
Offshore exploration and production operations in sea ice conditions mustface the challenges of working in frontier environments. In the context of thecorresponding regulatory environment, operators will be expected to show thatnew technical and operational challenges have been addressed. Emergencyresponse in sea ice conditions is a case in point. In the event that marineevacuation of an installation is necessary, the lifeboat will have to becapable of being launched safely into ice, propelling itself away from thehazard area to some safe distance, and then affording a haven until personnelcan be recovered.
Some ideas are presented in this paper for improving the capabilities oflifeboats and for meeting the expectations embodied in regulations. The designand operational elements contemplated here are broadly based on model scaleexperiments and full-scale trials with conventional TEMPSC lifeboats that havebeen done over the course of a multi-year test program. Design considerationsinclude powering and propulsion, maneuvering, structural resistance to iceloads, and arrangement of the coxswain's cockpit (visibility). Operationalconsiderations include the coxswain's tactics in ice, simulator training forcoxswains, and ice management of evacuation routes. Finally, the use oftraining simulators for evaluating and demonstrating the efficacy of these andother improvements is discussed.
A program of model scale experiments and full-scale field trials has beenunderway for a period of several years to investigate the performancecapabilities and limitations of evacuation craft in sea ice. This paper focuseson a series of field trials with a small, conventional totally enclosed motorpropelled survival craft (TEMPSC). The lifeboat was tested in pack iceconditions in an ice channel cut in landfast ice on a freshwater lake. Thechannel was about 55m long and 32m wide and the ice was between 300mm and 400mmthick (with an average measured thickness of 340mm). The ice that was cut outof the level ice sheet to make the channel was further cut into floes of twobasic sizes, the smaller about 1.65m×2m and the larger about 3.2×2m. Thesecorresponded to floes that were about 30% and 50% the mass of the lifeboatitself. The ice concentration in the channel was controlled by removing some ofthe ice floes from the channel. Several ice channel transit tests werecompleted, starting with a pack concentration of 9/10ths. At the end of thetests in those conditions, more ice was removed from the channel until thegross concentration was 8/10ths and another set of transit trials was done.This process was repeated for consecutive concentrations of 7/10ths, 6/10ths,5/10ths, and 4/10ths. The same procedure was used in model scale tests reportedby the same authors (Simões Ré & Veitch 2003, Simões Ré et al. 2006).Indeed, the field tests replicated the model scale experiment conditions to theextent practicable. The field trials were done over a five-day period in March2010.
The paper provides information on a unique vehicle, the amphibiousHoverbarge which can be used for transporting heavy cargo, modules and drillingrigs over Arctic terrain, such as snow, ice and tundra. The paper draws uponexperience of Hoverbarge operations in Alaska back in the 1970s along withrecent technical developments of the Hoverbarge to make it more suitable forArctic operations, including skirt ice protection and selfpropulsion.
The paper also highlights important environmental advantages the Hoverbargecan bring, hovering cargo and equipment above the tundra whilst only exerting1psi ground pressure. In addition the paper explains how the Hoverbarge canmeet current demands to extend operating seasons and transport heavy loads suchas pre fabricated modules without building new infrastructure.
Results, Observations and Conclusions
The paper also focuses on the potential of transporting cargo during summermonths when winter roads are not in use and the subsequent advantages that thisbrings.
Significance of Subject Matter
Although first developed over 35 years ago, the Hoverbarge remainsrelatively unknown to current day engineers. This paper seeks to increaseawareness of this technology which may solve a number of current logisticalissues.
As more attention is paid to the exploration of oil and gas resources in thehigh north, the settlement of the disputed area between Norway and Russia, andthe world's ever-rising demand for energy resources, more and more oilcompanies and suppliers are moving north. For most oil companies, rig and shipoperators and logistics providers, the Arctic represents a new frontier, whereexisting operational systems and technologies are tested to their limits. Thispaper outlines key challenges facing the development of sustainable and safemaritime offshore operation in Arctic waters. The Arctic offers challengesrelated to harsh weather conditions, long distances from bases, limited orabsent infrastructure, a sensitive ecosystem, ensuring safety at sea, potentialoil spills and operations in ice-infested waters. Arctic operations are thussignificantly different from operations in the North Sea. This state of affairsunderlines the need for new or improved organisational and business models forintegrated logistics operations, value chain management and technologicalsolutions that will ensure sustainable and safe maritime operations. It alsodemands optimised design of ships and structures for operation in the Arcticenvironment as well as improved communication infrastructure based onsatellite, terrestrial, ship-to-ship or ad-hoc systems, radar and opticalsatellites. Key features discussed will include ideas and concepts forarea-specific vessel design and multipurpose vessels, with integrated supportand logistics models and systems, base-to-base operation and tailored businessmodels for robust Arctic field operation. The aim is to ensure a holistic andintegrated transport and logistics infrastructure in sparsely populated areaswith extreme weather conditions (polar lows, darkness, fog, ice and icing),including the interplay between vessel technology and the operationalmanagement.
Blunt, J.D. (ExxonMobil Upstream Research) | Garas, V.Y. (ExxonMobil Upstream Research) | Matskevitch , D.G. (ExxonMobil Upstream Research) | Hamilton, J.M. (ExxonMobil Upstream Research) | Kumaran, K. (ExxonMobil Corporate Strategic Research)
Safe and economic hydrocarbon exploration, development and productionoperations in the high arctic deepwater require a nuanced understanding of thesea ice environment. Robust image analysis techniques provide methods bywhich this nuance can be more objectively characterized and used for decisionmaking while in operations. Morphological segmentation and windowedstatistical analysis are proposed as two approaches that provide usefulinformation on the tactical scale by rapidly characterizing floe fieldmorphology and relative surface roughness. Their use is demonstratedwithin the context of actual high arctic field program data. Results fromthe method application are shown and the benefits and limitations of their useare discussed.
Wang, Cynthia (Keppel Offshore & Marine Technology Centre) | Quah, Matthew (Keppel Offshore & Marine Technology Centre) | Noble, Peter G. (ConocoPhillips) | Shafer, Randall (ConocoPhillips) | Soofi, Khalid A. (ConocoPhillips) | Alvord, Chip (ConocoPhillips Alaska Inc.) | Brassfield, Tom (ConocoPhillips Alaska Inc.)
Jack-up drilling units have been used in Arctic open water seasons and areaswith icebergs. They have not been used in areas where significant sea ice canmove in with high concentrations. These areas have typically been drilled usinga floating mobile offshore drilling unit (MODU) although the water depths aretypically less than 50 meters. Floating MODUs in shallow water depths can havesignificant downtime due to the limited offset in shallow water and typicallyrequire placing the well control equipment in a seabed cellar. In these areas,jack-ups can improve both operational safety and efficiency as they havelimited weather related downtime.
Several studies were carried out to determine the feasibility of using amodern high capacity jack-up MODUs for exploratory drilling in these areas.This paper will review the studies including structural analysis, icemanagement approaches, and well control considerations. It will also review thefurther potential of jack-ups in the Arctic.
Studies showed that using a jack-up drilling unit is feasible in shallowArctic seas such as the Chukchi Sea when coupled with an effective icemanagement system. The jack-up unit has sufficient ice resistance to withstandinteraction with thin early winter ice. Specific designs of jack-ups arecapable of taking impact forces from thicker ice floes that may occur during anice incursion event during the open water season. The maximum floe size duringan ice incursion is limited and controlled by the associated icemanagement system.
An ice management system was developed using a combination of satelliteimagery, ice management vessels, and ice alert procedures. This system wasdetermined as effective in managing ice to allow the jack-up to operate in theChukchi Sea area.
Environmental and personnel safety is enhanced by the use of aPre-positioned Capping Device, an in place source control device. The device isindependent from the rig's well control system and provides another level ofprotection in additional to the jack-up's BOP.
The conclusion, based on structural and ice management studies, is thatmodern high capacity jack-up drilling units can be an effective way to drillwells during the open water season in shallow waters of Arctic seas includingareas in to which sea ice can move. The studies also show that there ispotential for use in other areas.