Executive SummaryCarl Thaemlitz, Aramco Services Company
Greetings and welcome to the March edition of SPE Drilling & Completion. This first edition of 2014 introduces the new online-only format of our journal. I hope that you enjoy the access to historical volumes of SPE Drill & Compl and take advantage of our new iPad application for reading while on-the-go.
Our first paper, Real-Time Evaluation of Hole-Cleaning Conditions With a Transient Cuttings-Transport Model, presents theory and applications of a quantitative method for addressing poor hole cleaning conditions during the drilling process. The model accounts for fluid transport and drill string mechanics that when calibrated against actual well data, results in guidance as to what adjustments are needed in drilling parameters to avoid the formation of cuttings beds. The two applications investigated are North Sea operations involving a cement drill-out and a managed pressure-drilling operation.
Analogies between our industry and others such as medical or aerospace abound; but just how relevant are they? Our author takes a fresh look at the topic within Industry Analogies for Successful Implementation of Drilling-Systems Automation and Real-Time Operating Centers. A summary of analogies, assessments of their relevancy and thoughts on the future state of work flows are presented herein.
Drill bits having good hydraulic design help to guarantee the proper removal of the cuttings generated during drilling within the bottomhole section of the wellbore. Study of the Hydraulic Performance of Drill Bits Using a Computational Particle-Tracking Method discusses the current computational fluid-dynamics models often employed, while introducing a model that incorporates particle tracking. The result is improved representation of the multiphase nature of drilling fluids, which leads to better modeling of cuttings transport.
Although the geosteering technique for well positioning has been applied in various forms for many years, the authors of our next paper propose that there has not been a clear demonstration by the industry of a logically consistent approach for making geosteering decisions. A Decision Analytic Approach to Geosteering Operations presents us with a review of 40+ papers on the topic of geosteering, a framework by which to make geosteering decisions, and techniques by which to consistently update the anticipated formation uncertainties located ahead of the drill bit.
In certain offshore applications, riserless drilling during the top section of the wellbore has shown benefits through reducing drilling fluid costs while increasing the rates of penetration through salt intervals. Cost-Effective Ultralarge-Diameter Polycrystalline-Diamond-Compact-Bit Drilling in Deepwater Gulf of Mexico presents the application of Polycrystalline-Diamond Compact drill bits with rotary steerable drilling systems with the advantages and the challenges in mind. Case studies of field applications are addressed in detail, while clear recommendations are presented.
The evolution of a Canadian tight-carbonate formation’s drilling and production practices over the past 3 decades is addressed by the authors of Evolution of Drilling and Completions in the Slave Point To Optimize Economics. We are walked through the developments of vertical wells, single lateral wells, and multilateral wells, along with the evolutionary learning that has brought the operations to their current state. Economic evaluations of cemented liners and openhole completions are also discussed.
The authors of our next paper propose suitable knowledge to operators for the design of well completions and fracture treatments to maximize reservoir drainage and increase the estimated ultimate recoveries of resources, which is achieved through an increase in fracture complexity. Impact of Completion Design on Fracture Complexity in Horizontal Shale Wells presents the use of a 3D geomechanical model to simulate the stress reorientation caused by opening fractures and to illustrate the horizontal stresses through contour mapping. Improved conductivity within zones having low contrasts in horizontal stresses and potential interactions with natural fracture networks are addressed in detail.
Engineering Cementing Solution for Hutubi Underground-Gas-Storage Project presents the unique challenges for cementing such storage areas, and how the solutions were achieved. Pressure- and temperature-related stresses anticipated during injection and withdrawals were simulated through a model, which provided the basis for the design of the cement system. Case histories from field applications on 17 wells are cited to demonstrate the success of the process.
The authors of our third completions paper present compelling reasons for considering chemistries other than inorganic salts for reducing the hardening time for cements in certain applications. Nanosilicas as Accelerators in Oilwell Cementing at Low Temperatures presents a novel investigation of the effects of silica particle shape upon cement hydration kinetics. Lower permeabilities and greater compressive strengths for lightweight cements are advantages observed using nanosilicas in place of such salts as calcium chloride. Morphologies of the most effective nanosilica accelerators are also presented within the manuscript.
Effective drilling-fluids displacement and zonal isolation are greatly enhanced by proper centralization of casing within the wellbore. Comparing Soft-String and Stiff-String Methods Used to Compute Casing Centralization takes an in-depth look at the current API Specification 10D (soft-string) model for calculating casing centralization along with comparative illustrations of benefits that may be realized by using stiff-string methods based upon finite elemental analyses. Results for both types of calculation models are compared in several field cases.
Studies into the understanding of seabed subsidence during methane hydrate production are at the heart of our next paper Evaluation of Frictional Properties for Methane-Hydrate-Well Completion and Production. Settlement of seabeds can cause a host of wellbore-integrity issues if zonal isolation and casing support are compromised. Triaxial testing procedures are used to evaluate the frictional interaction of steel with sand and with cement. Insightful conclusions are presented from the experimentation.
A variety of chemical blocking agents, often referred to as fluid-loss pills, are used during various well workover operations to prevent the loss of wellbore fluids to the producing formation. Natural polymers cross-linked by boron are one common choice, but thermal stability is often poor. Solids-Free Fluid Loss Pill for High Temperature Reservoirs introduces us to thermally stable, synthetic polymers as next-generation solutions for formation friendly temporary shutoff events. Thorough laboratory investigations are reported and discussed.
Our final paper, Assessing Wellbore Integrity in Sustained-Casing-Pressure Annulus, presents an analytical solution to an earlier model for gas migrating through the cement sheath and up the annular fluid column. Validation of the model is presented with field examples from gas wells and oil wells. The current diagnostic procedures for sustained casing pressure are discussed along with their potential shortcomings. The modeling discussed is presented as a candidate basis for standardization of sustained casing pressure testing.