Mitchell

A Progress Report

In the March 2008 edition of the SPE Drilling & Completion Journal, we described the problems with the journal-review process and how we hoped to resolve them. While we have not yet met the goals we set, there has been significant progress. The first problem was the backlog of papers accepted for publication. In the March 2008 issue, a total of 9 papers were published, in the current issue there are 20 papers. The second problem was to exercise more control on the papers submitted from conferences. In 2007, there were 509 manuscripts submitted for review, and in 2008, there were 295 manuscripts submitted. The third problem was papers that had been in the system for more than 12 months. In 2007, there were 88 papers that were in review for more than 12 months, and in 2008, there were 5 (though our goal is zero). We have increased the size of the editorial review committee--associate editors from 5 to 6, and reviewers from 71 to 104. Expect further improvement for 2009.

This month there are twelve drilling papers and eight completion papers for a total of twenty papers.

Drilling Papers

Human-Factors Implications of Remote Drilling Operations: A Case Study From the North Sea. Real-time data transfer has given rise to remote monitoring, reducing personnel on board and cost. The real challenge lies not with the technical feasibility, but with the impact on work processes, which is poorly understood. For example, onshore teams generally approved of the concept, but the offshore response was mixed, with both strong support for its innovative potential and critical voices about system reliability, contractual concerns and the impact on work-life balance. This is an important and highly recommended paper. Drilling and Completing High-Angle Wells in High Density Cesium Formate Brine--The Kvitebjørn Experience, 2004–2006. Drilling and completion fluids based on cesium formate brines were selected by Statoil for the high-pressure/high-temperature (HP/HT) Kvitebjørn field. Cesium formate brine was selected primarily to minimize well-control problems and maximize well productivity, but the use of the same fluid system for both drilling and completion also gave the benefits of simplified operations, reduced waste, and elimination of fluid-incompatibility problems. Optimization of Deep-Drilling Performance--Benchmark Testing Drives ROP Improvements for Bits and Drilling Fluids. This paper describes benchmark testing of advanced diamond bits and HP/HT drilling fluids at high pressures. PDC bits and drilling-fluid compositions with properties that promote invasion, without causing formation damage, both showed promise for improving drilling efficiency in hard rock at high bottomhole pressures. Hydraulic Predictions of Polymer-Thickened Foam Flow in Horizontal and Directional Wells. Foam has proven to be effective and economical in underbalanced operations, and it is gaining wider applications in many areas. This paper summarizes the significant effects of polymer on foam rheology and presents a hydraulic model that simulates aqueous- and polymer-based foam flow in directional and horizontal wellbores. A Novel Approach for Determining, Evaluating, and Applying Stress-Concentration Factors for Rotary-Shouldered Connections. In recent years, drilling programs have become significantly more aggressive, and as a result, rotary-shouldered connections often experience exceptionally elevated stress conditions. This paper presents a series of evaluations to find a logical and conservative approach to evaluate the maximum peak-stress behavior in rotary-shouldered connections in response to operation loads. How Good Is the Torque/Drag Model? The torque/drag model is a simplified drillstring analysis that has been almost universally adopted by the industry. In general, this model has agreed well with field experience, but occasionally it has failed. This paper reviews the torque/drag-model assumptions in depth, with many surprising discoveries. Both strong and weak points of the model are discussed, with suggestions for model improvement and tests to evaluate model performance for specific cases. Defining the Limits of Tubular-Handling Equipment at Extreme Tension Loadings. While landing string designs have progressed, the design of the handling equipment, until recently, has been based upon conventional slip technology. Because of the increasing loads being placed on landing strings and the associated handling equipment, an array of tests were performed to better understand the handling equipment currently in use for landing heavy loads. Five different sets of handling equipment were tested, including four conventional slips and an unconventional slipless system. This paper gives complete details of the experimental procedures and the results of the tests. Special Issues in the Stress Analysis of Casing Strings in Steam-Injection Wells: Mathematical Development and Design. The design of tubulars for steam-injection wells is complex. Because the tubulars in these wells invariably experience inelastic loading, issues such as the effects of temperature on the static and cyclic (fatigue) material properties become important. This paper presents a mathematical model of casing strings subjected to thermal loads in steam-injection wells. The model includes the effects of temperature on material properties and the effects of wellbore curvature and prestress during the heating cycle. Sealing Capacity of API Connections--Theoretical and Experimental Results. Hydraulic fracturing has become a state-of-the-art stimulation technique. However, the high pressures that are achieved during the pumping phase require the understanding of leak resistance of API connections. This paper presents the experimental results of the tests carried out on four different thread compounds using the improved "grooved-plate" method. From these tests, a chart is presented that gives the real connection resistance based on its initial makeup torque. Cement-Shrinkage Measurement in Oilwell Cementing--A Comparative Study of Laboratory Methods and Procedures. The main purpose of a primary cementing job is to provide effective zonal isolation for the life of the well. A path for fluid migration could be created if the cement sheath fails either because of shrinkage and/or because of loss of structural integrity from its lack of capacity to withstand stresses from well operations. This paper focuses on the contribution to near-term cement-sheath failure from shrinkage. The results presented in this work can be used to test shrinkage characteristics of cement slurries in the laboratory, under downhole conditions, and, by using these results, select the right cement system. Evaluation of the Potential for Gas and CO2 Leakage Along Wellbores. CO2 storage in geological media requires a proper assessment of the risk of CO2 leakage. In this paper, the important factors for predicting which wellbores are most likely to leak were determined. The analysis was based on a survey of data from more than 315,000 wells drilled up to the end of 2004 in the province of Alberta, Canada. Finite-Element Studies of Near-Wellbore Region During Cementing Operations: Part I. As stated before, a wellbore cement sheath is expected to provide zonal isolation and borehole integrity during well construction and well life. Cement sheaths mechanically interact with other elements in the wellbore region to stresses from geological processes and operational activities. Quantifying these interacting physical components and processes has technical, economic, and environmental significance. A staged finite-element approach is proposed that allows one to follow the development of stress and strain state during all stages of the well life.

Completion Papers

Evaluation of Sand-Control Completions in the Duri Steamflood, Sumatra, Indonesia. One of the biggest problems associated with the production of the crude oil in the Duri field in Sumatra, Indonesia was the production of massive amounts of solids. The results of an evaluation program showed the completion designs and sand-control screens were up to industry standards; however, several operational aspects were identified as opportunities for improvement. Lessons Learned on Sand-Control Failure and Subsequent Workover at Magnolia Deepwater Development. Because of the long lengths of the producing reservoirs and large variations in sand-grain sizes in the Magnolia field, premium screens with shunt tubes in conjunction with cased-hole frac packs have been used to complete the wells. The third well failed during initial unloading, allowing unacceptable rates of sand production. A detailed examination was conducted in conjunction with laboratory collapse and erosion testing of the premium screens. Revised operational procedures were used in six subsequent frac packs without any additional failures and zero-to-negative completion skins. Sand Exclusion and Management in the Okwori Subsea Oil Field, Nigeria. Several downhole sand-control failures in Okwori subsea oil producers resulted in a significant overhaul of the downhole sand-control method and a review of topside-sand management. A revised openhole sand control was designed, together with changes in drilling practices, reservoir drill-in fluid, and filter-cake cleanup techniques. Magnolia Deepwater Experience--Frac Packing Long, Perforated Intervals in Unconsolidated Silt Reservoirs. ConocoPhillips is developing the Magnolia field with wells producing primarily from massive, fine-grained, Pleistocene reservoirs that require sand control to prevent sand production. This paper discusses screen selection in silt/very-fine-sand reservoirs, carrier-fluid selection, perforation strategy, the ability to frac across shale intervals, and the effectiveness of achieving a frac pack with premium screens with shunt tubes. Challenges, Lessons Learned, and Successful Implementations of Multilateral Completion Technology Offshore Abu Dhabi. An integrated approach for the trial planning and implementation, and lessons learned, from a predesign trial led to reaching the final goals of independent coiled-tubing access to the upper and lower laterals, for performing effective stimulation and reservoir monitoring. Delivering a Fully Qualified HP/HT Production Packer Following Field Failure. The failure of a primary barrier on a completed HP/HT well resulted in a significant pressure increase in the production annulus, requiring a complex well-kill operation to resolve. The failure investigation found no clear cause, but a test demonstrated that very small irregularities in the internal-casing profile would cause the packer casing-seal to fail. A packer-seal system was successfully developed that could withstand the specified degree of casing irregularity. Quantification of Overbalance-Induced Invasive Damage and the Estimation of Equivalent-Skin Effect on Production. An important premise of underbalanced drilling (UBD) is the productivity improvement it delivers through mitigation of invasive damage. Characterization and quantification of such damage, therefore, becomes necessary for assessing the value delivered by UBD. This paper details a novel approach that combines dynamic microscale-reservoir simulations, calibrated to special core tests to model the extent of invasive damage, and its impact on flowback during production. Two field cases are discussed in detail. Qualifying Proppant Performance. To qualify proppant performance, specific quality-control procedures must be rigidly followed, consisting of representative sampling from a flowing stream, standardized testing with calibrated equipment, and sample retention for follow up evaluation. This paper addresses how to apply these principles to evaluate the performance characteristics of delivered proppant.