Drilling activity has increased rapidly in Iraq over the last few years. With the lack of reliable downhole data to develop a solid strategy to optimize drilling operations, the drilling performance has been inconsistent with frequent failures of drill stem components. Without the aid of quality downhole data it is very difficult to identify the root cause of these failures, and more importantly, provide a means to identify a solution to improve performance. This paper showcases a project in South Iraq where modeling of the drilling BHA's using a unique Finite Element Analysis software package identified critical natural frequencies of the drillstring. The integration of high frequency downhole vibration data collected in multiple positions of the string provided the evidence to validate the vibration road map delivered by the BHA analysis.The objective of the project was to identify the primary vibration mode, evaluate the vibrations severity, cause and source in the 12 !" vertical section and provide recommendations to achieve performance improvement through controlled step changes in bit & BHA design, drilling parameters and operational procedures. The pre-well BHA model analysis identified that the premature bit failure was a direct result of lateral vibrations induced by operating in a critical lateral harmonic zone. This was validated with the downhole vibration data.A well-established optimization process including expert detailed analysis of the high frequency downhole vibration data provided a clear understanding of the relationship between the pre-well BHA model, the drilling parameters planed and the associated downhole drilling dynamics.The impact on performance was clear. Implementation of the new recommended drilling parameters derived from the BHA analysis applied to the same bit and BHA used in Well #1 resulted on a 26% increase in drilling performance in well 2. 2-IntroductionThere are multiple drillstring dynamics modeling software packages available in the industry that enable any drilling team to do a pre-well analysis of each BHA design and model the downhole behavior of the system. Most these packages provide the similar approach of using Finite Element Analysis of the entire string to calculate the combination of drilling parameters based on a proven, scientific approach that will most likely initiate downhole vibration and high impact loading that leads to premature bit and/or downhole tool failures.It should be a requirement to run such modeling analysis for every BHA for two main reasons. First it allows the drilling engineer to twick the BHA design to minimize the impact of the natural resonant frequencies on the system performance. And second, and in case the BHA design remains the same, it ensures that the drilling parameter combination selected (weight and surface RPM) will not initiate disruptive harmonics generated from the natural frequencies of the system itself.

Drilling hard, abrasive volcanic rock has presented significant technical challenges to bit manufacturers over the years, creating a dilemma for operators designing a strategy to efficiently drill difficult volcanic intervals. This paper will focus on the development of a unique concentric two-stage, dual-diameter PDC bit coupled with a low-speed, high-torque motor, providing an alternative solution for drilling a challenging section featuring a hard volcanic layer for a major international operator in a remote location West of Shetland. The paper reviews the design concepts of the bit that allows an initial smaller pilot hole to be drilled, relieving the stress of the surrounding rock. The larger reamer section subsequently enlarges the hole to the desired diameter through stress-relieved rock, thus requiring less energy to remove a comparative volume of rock. The unique design concept was tested in an in-house pressurized drilling laboratory with basalt samples of varying compressive strengths to evaluate its performance in these challenging rock types. Alternate bit designs with a variety of cutter geometries and cutter layouts were also evaluated and an optimum design was selected for the field test to deliver lower vibrations and increased ROP. A strategy was formulated to drill the interval in a single run with the optimal dual diameter PDC bit and a low-speed, high-torque mud motor. Downhole dynamics data recorders were placed in the BHA to capture downhole dynamic activity to evaluate performance and provide information to help further optimize performance through the interval. On the subject well, the new dual-diameter PDC design successfully drilled the entire 12 ¼-in hole section in a single run, including 67 m of volcanics. The design achieved a record ROP for the section, saving five days of drilling time and resulting in significant cost savings for the operator. In addition to providing measurable stability and drilling efficiency benefits in conventional applications, the unique concentric dual-diameter PDC bit also provides a technical solution to operators looking at more cost-effective means of drilling these challenging formations in a high-cost drilling environment.

With the current low oil prices, Operators are under increasing financial pressure to look at new ways to safely maximize the value of their assets whilst operating within the constraints of the regulatory guidelines. Many operators have placed a greater emphasis on restoring existing wellbore integrity to develop their assets more efficiently instead of performing an expensive side-track or drilling costly new replacement wells. This paper will review the challenges faced by a major American Operator while drilling an unconventional well in the Marcellus Shale Basin where casing integrity issues arose. Solid expandable tubular technology has provided operators with a cost effective solution to remediate wellbores for a number of years. Since 2009 the High Performance (HP) solid expandable patch has been installed in over 170 wells, addressing completion / production issues, however, these systems had always been run on jointed pipe. The recent (2015) deployment of an HP expandable patch on coiled tubing for the operator provided a technical and more economically attractive solution over alternative options. The planning, procedures and execution of this first ground breaking installation will be discussed in this paper. The operator required a solution to seal off squeeze perforations which would have to withstand high pressure fracturing operations. The area regulatory agency had suspended their operations, not allowing completion of the well due to a poor cement bond behind the production casing. This required remediation using a perforation and squeeze operation. The cement squeeze alone would not hold up to the high pressures required to fracture the well. An HP patch provided the optimum solution that would meet the requirements to complete the well. Side-tracking or drilling a costly replacement well, did not provide an economic option. A coiled tubing unit was used to perform the required cement squeeze. Since the HP patch could be run on coiled-tubing, it eliminated the need to mobilize additional equipment saving the operator time and money. After squeezing cement, the 4-1/4in HP patch was successfully installed into the 5-1/2in casing covering the squeeze perforations and then tested to 9,900 psi, - more than enough to withstand the planned fracturing pressures. Careful planning and operational support gave the client the confidence to install the expandable HP patch on coiled tubing to fully restore their well integrity. Over the last few years the HP patch has been developed to be deployed by various methods, thus providing significant opportunity for operators to revitalize their wellbore with a more effective and economical outcome.

A 3 ¼" ultra slim rotary steerable system (US-RSS) has been developed for use in through tubing rotary drilling (TTRD), with the objective of extending the production profile of offshore maturing fields. The introduction of RSS increases the capability of enhanced reservoir development by extending the reach of TTRD, improving drilling performance, increasing production from precise directional control, and lowering overall drilling costs. This development project was a collaborative effort involving several major operators to partially fund production of this ultra slim RSS that could pass through 5" completion tubing. This paper provides an overview of the RSS tool development including system testing at a full scale rig. This testing clearly demonstrated the directional functionality as well as successful communication between the measurement tools and RSS. The testing also allowed design iterations to be made to the drill bit so that the stability, side cutting and hydraulics were optimized and specifically matched to the operating mechanism of the tool. Due to the success in testing, the RSS and bit was taken forward into field trial. Several runs were undertaken with the US-RSS for Dubai Petroleum. In an initial application, the assembly was utilized to drill a dual lateral oil producer / injector that traditionally would have been cost prohibitive due to time, or impossible due to torque and drag considerations. This lateral was achieved, including successful completion of the first ever ultra slim open-hole sidetrack. The objective of a recent application was to drill the horizontal drain of a re-entry well. Use of the US-RSS delivered a saving of 6 days in time and approximately $1.8million in cost. The assembly also achieved a world record for footage with a US-RSS, drilling over 2000' with ROP 30% higher than the average produced with downhole motors. Introduction The US-RSS is an essential tool in the quest to drill sub-5 ½ in. wells with complex profiles so commonly required in the crowded subsurface environment of a modern, mature field. A US-RSS enables significantly improved performance and flexibility over more standard slide drilling options by improving hole quality, ECD and weight transfer even in very high Dog Leg Severity (DLS) and long step out well plans. This was a critical component of the successful operations to drill the long step out drains in the application for Dubai Petroleum. The Advantages of Ultra Slim RSS are numerous;The control of hole quality and cuttings management is essential to effective Ultra Slim well development as this enables targets further away from the mother bore to be reached before the traditional limitations of ECD and stand pipe pressures limit the step out possible. A fully rotating RSS system will improve weight transfer and hole quality while reducing or preventing the cutting beds often seen to build up during slide drillingA high dog leg capability allows more complex well plans to be achieved and also enables kick off lower down in the reservoir allowing deeper, shorter sidetracks

fax 01-972-952-9435. AbstractDrilling the 12 ¼" and 8 ½" sections in offshore Abu Dhabi's Deep Khuff fields is very challenging due to an intricate geological sequence that consists of limestone, dolomite and shales that are highly interbedded with hard stringers. Historically, ADMA-OPCO, the operator, has attempted to efficiently drill the section using roller cone tungsten carbide inserts (TCI), natural diamond and polycrystalline diamond compact (PDC) technology.PDC bits yielded better performance in terms of rate of penetration (ROP) and bit life over TCI bits. However, it required several PDC bits to drill the sections. Further detailed analysis produced optimum PDC designs that successfully established new benchmarks in the fields.