Successful Sand Control Design for High Rate Oil and Water Wells
Authors: Schwartz David H. 
Published: December 2007

Successful sand control in high rate oil and water wells can be achieved by following this procedure: define the sand, design the gravel, control the placement, and stabilize the pack once it is in place.

Introduction

A key factor affecting the profitability of waterflooding heavy-oil, unconsolidated-sand reservoirs is the ability to achieve effective sand control completions in response and injection wells. Effective sand control reduces liner failures, simplifies individual well operating problems, and protects expensive pumping equipment required for high producing rates.

A survey of the literature and current completion practices indicates that the gravel flow packed liner practices indicates that the gravel flow packed liner completion is the best method currently available for controlling sand in unconsolidated sand reservoirs subjected to high rate waterflooding. However, to be effective over the life of a typical waterflood (10 years or more), the gravel flow packed completion must be carefully designed and properly installed.

Presented here is a method for designing a gravel flow packed liner completion, based on the following considerations:formation analysis,gravel-to-sand ratio,formation sand uniformity, andvelocity through slots.

The technique is developed from the technology and experience of the water-well and petroleum industries, noting that continual improvement in well completions is necessary to achieve or maintain profitable secondary recovery projects.

Literature Survey

For over 30 years a number of investigators looked for a way to control sand. Laboratory experiments with sand, bridging over rectangular perforations, brought about the designed slotted liner. But even with reasonable empirical formulas and factors of safety, only a measure of control was possible in unconsolidated sand reservoirs. The problem increased when secondary recovery operations made possible the production of relatively large volumes possible the production of relatively large volumes of fluid.

How was it, then, that water wells could produce thousands of barrels of sand-free fluid through small intervals? The water-well industry had been using the gravel flow pack completion method with such success that, in many areas, the technique was a standard completion practice as early as 1916. The oil industry rapidly began to research the gravel flow pack. By the mid-forties there were enough field data pack. By the mid-forties there were enough field data to confirm the investigators' theoretical conclusions. Once the basic design requirements were established, completion techniques were improved so that today practically every aspect of a well designed flow pack is practically every aspect of a well designed flow pack is defined in the literature.

Basic Design Considerations

The function of the gravel flow pack is to act as a filter, allowing natural fluid movement but preventing formation sand grains and other solids from entering the wellbore. Bridging of the formation against the gravel pack is the key to the control of sand movement.

When effective bridging is achieved, sand and other solid particles carried by the formation fluids are deposited at the pack's periphery, allowing clean fluids to be produced.

JPT

P. 1193