Michael L. Wiggins

Analytical modeling of gas recovery from in situ hydrates dissociation

Exploration activities around the world have confirmed that in situ hydrates are widely available in permafrost and oceanic sediments. These hydrocarbon deposits have stimulated worldwide efforts to understand gas production from hydrate dissociation in a porous media. This work is a contribution towards these efforts. The present study uses depressurization-driven in situ hydrate dissociation, incorporates decomposition kinetics into the radial diffusivity equation, and develops a model to predict the performance of naturally occurring hydrates. The proposed model is simple yet useful and it does not require any empirical correlation. The model-predicted performance compares well with the published experimental studies on the hydrate dissociation in porous media.

A Review of Downhole Separation Technology

Downhole oil/water separation (DOWS) allows water to be separated in the wellbore and injected into a suitable injection zone downhole while oil, with traces of water, is produced to the surface. After introduction of DOWS in the 1990s, several trial applications were undertaken to test the technology. These trials allowed information to be collected on DOWS feasibility. The full-length paper reviews the status of downhole separation technology and presents an extensive list of references.

An Approach to the Optimum Design of Sucker-Rod Pumping Systems

Sucker-rod pumping system design is often a trial and error process. Many simplifying assumptions are used which may not be consistent with the well conditions. This paper presents a new methodology for the optimum design of pumping unit systems. In this approach, plunger diameter, polished rod stroke length, pumping speed and pump intake pressure are chosen as basic design variables. Production rate and rod string taper are determined by an iteration algorithm which systematically couples well inflow performance and vertical flow effects into the design process. Polished rod load, peak gear box torque, polished rod horse power and counterbalance effect are also determined at the end of the iteration calculation. Different design objective functions can be used to rate the pumping modes. Thus, the optimum design of pumping unit systems becomes a matter of solving for the combination of the four basic design variables which maximize or minimize an objective function within the limitations of available equipment by a mathematical programming method.

Optimizing Plunger Lift Operations in Oil and Gas Wells

Many low volume oil and gas wells produce at suboptimum rates due to liquid loading. This situation is caused by an accumulation of liquids in the wellbore that creates additional backpressure on the reservoir and decreases production. Plunger lift is an artificial lift technique characterized by the use of reservoir energy stored in the gas phase which is used to lift liquids to the surface and has proven to enhance the performance of these wells Unfortunately, the lack of a thorough understanding of plunger lift systems has often led to disappointing results in actual applications. This paper presents a discussion of plunger lift and the dynamic interaction of the mechanical plunger lift system coupled with the reservoir behavior In this study, a dynamic plunger lift simulator is used to investigate various operating scenarios for both oil and gas wells. Analysis of the results provides improved insight into the efficient operation of plunger lift systems.