fax 01-972-952-9435. AbstractSince their introduction in 1997, rotary steerable drilling systems have delivered significant gains in drilling efficiency. In addition to this fundamental benefit, these systems have enabled more challenging wells to be drilled at low risk with a wide range of other advantages, including improved well placement, etc.Continuous rotary drilling operations do however bring with them certain challenges which must be considered before rotary steering is selected for use. These include instantaneous penetration rate, specifications of rig rotary equipment, casing or drillpipe wear, stress on the drillstring, loss of drilling power through wellbore friction and drilling dynamics.Using high powered drilling motors, traditional performance drilling has been applied since the early 1990's to improve penetration rates by applying high power and consistent operating parameters directly to the drillbit. This has however been limited to straight holes or the most basic of directional profiles.A system has been developed which integrates a specially designed high power drilling motor within a high speed rotary steering assembly. By using this new system: • many of the challenges of continuous rotary drilling are mitigated, • more complex wells benefit from the advantages of traditional performance drilling, • existing drilling envelopes can be extended to further improve field recovery. This paper discusses the engineering design of the complete system, including the specially designed motor and high speed rotary steering system. The paper then goes on to discuss specific applications where the system should be considered for use, illustrated with results from real examples.

fax 01-972-952-9435. AbstractDuring the past 7 years, rotary steerable drilling technology has emerged from prototype status to a standard application world wide. This paper focuses on the latest generation integrated Rotary Closed-Loop System which now enables the industry to benefit from this technology in hole sizes from 5 7/8"-18 ¼". The paper discusses the integrated BHA concept and the sequential implementation of additional BHA components. Modular positive displacement motors placed immediately above the steering device simultaneously gives another step change in drilling performance while reducing casing wear and extends the drilling envelope. The paper provides an insight into applications where the integration into the rotary closed-loop BHA, of real-time Logging While Drilling (LWD) formation pressure measurements and real time acoustic property services has complimented, or indeed eliminated the need for, wireline logging runs.Using such an integrated Rotary Closed-Loop System in the Norwegian Troll Field created incremental production revenue of 6 Billion USD.

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractThe Iron Duke Field, offshore Brunei, Borneo is operated by the Brunei Shell Petroleum Company. Fourteen wells have been drilled in the Iron Duke area over the life of the field, with a high degree of local experience having been gained. One area of operations which has consistently been troublesome is that of performing controlled directional drilling. Following the recent introduction of Rotary Closed Loop System (RCLS) drilling technology, an in depth-study of offset well data was carried out to determine whether application of this technology was a solution to any of the common problems encountered. The results of the study showed that all of the identified problems could be eliminated through use of a Rotary Closed Loop Drilling System. A suitable well was identified as a trial for the system and tools were mobilised from Europe for use in the 8½" hole section. The results of the well clearly demonstrated many of the advantages in using this new technology, with the resultant hole section being of higher quality and delivered with a time saving of 55%. This paper outlines the common problem areas identified from the offset data study. It shows how application of the new technology eliminated these problems and resulted in a step change in both drilling performance and wellbore quality.

Wellbore tortuosity can be defined as any unwanted deviation from the planned well trajectory. As wells become more complex, oil companies increasingly perceive wellbore tortuosity as a concern in the process of drilling, completing and producing wells. Tortuosity is a potential source of additional torque/drag and can lead to problems while running casing, liners and completions. In specific applications, excessive tortuosity in horizontal wells can even impair productivity. Due to the conceptual difference in steering principle between conventional directional drilling systems, utilizing steerable bent housing motor technology, and rotary steerable systems, it has been claimed that rotary steerable systems produce a less tortuous wellbore. This effect has so far not been quantified, mainly due to the absence of a sufficient body of comparative data. In this paper, results of a tortuosity analysis of a number of North Sea wells drilled with rotary steerable systems, and offset wells drilled with steerable motors systems is presented. Various mathematical definitions of wellbore tortuosity and their implications are also discussed. The analysis shows that drilling with rotary steerable systems significantly reduces tortuosity. In tangent sections drilled with the rotary steerable system, superior inclination hold performance was observed and in areas of the wellbore where deviation changes were planned, more continuous curve sections were drilled. In order to illustrate potential benefits this may have with respect to drilling conditions, results from the evaluation were used to carry out torque/drag simulations. Levels of tortuosity produced by steerable motor systems and rotary steerable systems were calculated from the well data studied. These values were superimposed on a generic well profile. It was found that the torque reducing effect of the lower tortuosity delivered by the rotary steerable system is quantifiable and in some cases significant. Introduction The term wellbore tortuosity refers to the crookedness of an "as-drilled" wellpath. It is not a measure of the complexity of a three dimensional wellplan in itself - though the term is sometimes used incorrectly in this context - but a measure of the inevitable, unwanted undulations around it. As directional wells become longer, deeper and more complex, oil and service companies increasingly perceive tortuosity as a concern in the process of drilling, completing and producing wells. Tortuosity is a source of additional torque and drag while drilling and may result in problems while running casing, liners and completions. In addition, the increase in drillstring-casing contact can add to drillstring and casing wear. In specific applications, excessive tortuosity in horizontal wells can even impair productivity. In principle, wellbore tortuosity can be evaluated based on the directional wellplan and the survey of a well or section of a well. There is no industry standard for the numerical evaluation of wellbore tortuosity. In this paper, various mathematical expressions for tortuosity and their implications are discussed. In addition, the tortuosity of a number of North Sea wells has been evaluated in terms of these definitions, focusing in particular on differences in tortuosity levels of sections drilled with steerable bent housing motor technology as opposed to sections drilled with a rotary steerable system, the AutoTrak™ Rotary Closed Loop System. As an illustration of the impact of tortuosity on drilling efficiency, implications for torque/drag of the differences in tortuosity levels found have been further investigated and quantified.

Technology Focus Irrespective of industry or sector, the objectives of innovation are productivity and performance improvement and cost reduction. In the case of horizontal or complex geometry wells, innovation has delivered technologies targeting cost reduction and productivity improvement. While the advantages of these are realized in use, the true value is rarely calculated. As a result, the cycle of slow implementation of new technology continues and the pace of innovation is never optimized. As innovation delivers more technology choices, the well engineer’s work when forming technical recommendations and evaluating performance becomes more complex. Adding further complexity is the fact that combinations of technologies and associated services increasingly interact to deliver secondary benefits, not all of which are immediately obvious. Many of these benefits affect the productivity of a well over its entire life cycle. As a consequence, they become significant, but their overall value is challenging to confidently quantify for consideration. In a conventional operator/service-company relationship, the buyers are frequently cost managers. As a consequence, decisions tend to be biased toward unit cost. Beyond that, the value of a technology selection is normally determined more on the short-term cost saving than on the longer-term asset-added value. For example, saving 2 days of drilling time or eliminating a hole section is sometimes considered more important than a long-term incremental-production benefit over a well’s entire life, even though the cumulative value of the latter may be far greater. While there are exceptions, this is a roadblock to the take-up of new technology. As a consequence, the pace of innovation reduces, slowing productivity or performance improvement. As an industry, we need to consider factors that slow the pace of innovation. These scenarios indicate a need for new levels of competency to evaluate choices and optimize how we apply combinations of technologies. We must improve how technical recommendations are made by using risk-based, true return on investment and not deferring to unit cost or limiting justifications to immediate tangible gains. There is also a case to rethink the traditional cost-biased interfaces and business models between service suppliers and operators. The papers selected this year include examples in which the value of innovation is recognized and steps were taken to optimize application in horizontal wells. Recommended additional reading at OnePetro: www.onepetro.org. IPTC 16872 Production Transformation in Horizontal Wells’ Oil Recovery and Revival in Shallow Volcanic Fractured Reservoir by ICD’s OH Completions Success, Central Thailand by B. Edward, Pan Orient Energy, et al. SPE 164841 Using Real-Time High-Resolution LWD Images To Navigate and Optimize Multistage Completions in a Carbonate Reservoir by Sandeep Janwadkar, Baker Hughes, et al. SPE/IADC 163494 Successful Application of Concentric-Casing Nitrogen Injection To Overcome Drilling Challenges and Deliver a Record Horizontal Well in the Tecominoacan Field by Reginaldo Rodriguez, Pemex, et al.