Managed pressure drilling and annular flow background ...

In his early books Borehole Flow Modeling in Horizontal, Deviated and Vertical Wells (Gulf Publishing, 1992) and Computational Rheology for Pipeline and Annular Flow (Elsevier, 2001), Mr. Chin pioneered the use of boundary-conforming, curvilinear grid systems to model geometrically complicated borehole annular cross-sections with high eccentricity, cuttings beds, washouts and fractures.

These models, validated by lab and field experiments, and first to compute non-Newtonian power law flows in real boreholes, drive portions of key industry simulators, e.g., Halliburton's OptiCem, BakerHughes Inteq's Advantage, Brown and Root's pipeline debris models, Halliburton's recent Displace 3D transient, multiphase, cement-mud displacement simulator, and others.

We've licensed our drilling and cementing models worldwide. But innovation and progress require ongoing research commitment. So we stepped back and questioned every assumption and each line of computer code.

We'll share our findings with you right now.

Areas for improvement identified (and recently fully completed) ....

• Non-Newtonian viscosity. Our momentum equations modeled apparent viscosity, variable within the annulus, but for numerical stability, neglected its partial derivatives.

• Yield stress fluids. Shear flow exists above the yield stress, but below it, fluids move like solid plugs. While models exist for circular pipe and concentric flow, plug zone size and shape are unknowns for eccentric holes. Thus, the most important problems in drilling and cementing cannot be formulated, let alone solved.

• Drillpipe and casing rotation. Understanding rotation is important in hole cleaning and cement displacement efficiency. And because pipe rotation strongly affects annular pressure, its use provides a means for managed pressure drilling downhole flow control and safety monitoring ... but only if numerical stability, problematic until now, can be achieved.

• Transient conditions. Unsteady annular flow models are almost absent from the petroleum engineering literature. Yet, none can deny their importance, e.g., general pipe or casing reciprocation, arbitrary rotation, coupled actions, mudpump ramp-up and down, all useful in assessing bit-bounce, torsional stick-slip and transient stress effects.

• Multiphase effects. Recent three-dimensional, transient, multiphase models for cement-mud displacement solve the flow equations incorrectly. While "generalized Herschel-Bulkley" formulas improve curve-fitting, the computer logic needed to evolve embedded plug zone size and shape in eccentric holes was not available until recently. Thus, computed results for yield stress fluids in real annular geometries, even for steady flow, have not been accurate.

• Physical problem hierarchy. In "proof of concept" studies, the full three-dimensional, transient, multiphase formulation solved fully coupled convection and diffusion equations (developed by Nobel Prize winner L.D. Landau). But, the "brute force" method is slow and unstable. Scale arguments suggest we determine fluid interfaces kinematically from pump schedules, slug flow properties then from two-dimensional steady and transient solutions, and finally, mixing characteristics by "zooming" into transition zones using boundary layer theory ... such approaches allow rapid computations and improved accuracy.

• Real geometries, real answers. All of these limitations have been overcome with rigorous math and numerics. Importantly, our solutions apply to real annular geometries like those in (a) and (f) ... and we can model a fracture in a Texas-shaped well with the worst possible fluids without computing penalties. Automated mesh generation, equation setup and solution, plus three-dimensional color graphics displays, require mere seconds.

The final product ...

In 2009, StrataMagnetic Software, LLC, in competitive bidding, won a major half-million dollar contract with the United States Department of Energy to develop advanced annular flow models for managed pressure drilling job planning, rigsite machine control and cementing. The effort, with guidance from industry experts working with the Research Partnership to Secure Energy for America (RPSEA), allowed the developer to "tie up loose ends" while successfully addressing the above issues.

The Department of Energy has been pivotal in bringing our ideas to market. In addition to the RPSEA contract, we have won four prestigious Small Business Innovation Research (SBIR) grants over the past decade, all related to improving grid generation methodologies in petroleum engineering applications.

This work is summarized in the new book Managed Pressure Drilling: Modeling, Strategy and Planning scheduled for Elsevier publication in 2012 (this contains enhancements we can't discuss right now). The draft version below, developed from the final project report, is available to the general public. In it, flow problems are motivated and solved, with all computed results validated.

More than an academic exercise, the work demonstrates, for example, how drillpipe rotation can be used to control borehole pressures in managed pressure drilling, how helical flows with pipe reciprocation and rotation affect hole cleaning, and how non-Newtonian rheologies and pump schedules control cement-mud interface development during completions.

About the Author, click here. View Table of Contents now.

The definitive book on managed pressure drilling annular flow analysis is yours for $99 USD, plus $16 USD shipping and handling (total of $115 USD). Click "Add to Cart" to order directly from E&P Press at epPublishers@aol.com. Bulk discounts available.

Complete MPD_FS system, now available ...

Complimentary software. Contact the developer at wilsonchin@aol.com for your free fully functional copy of our MPD Flow Simulator system (you'll receive a private FTP link to download the 40 mb zip file). This trial is complimentary for fifteen (15) days, beyond which a registered license is required.

Unbeatable pricing. Can't wait? Unhappy with "proprietary" service company models? Purchase our comprehensive software system right now. You can obtain your individual license below or contact us to arrange for volume discounts and source code access.

Single-user licenses. Simply click "Add to Cart" and complete your online purchase through PayPal. Then advise us about your transaction, and send your UserName, e.g., John Smith, and Registration Number (see software sign-on screen from your computer) to wilsonchin@aol.com . We'll promptly send you the UnLock Code for your computer via email.