Oil and gas production from unconsolidated/weakly-consolidated sands requires a production screen in the hole to inhibit the movement of formation sand and keep the hole open. For open hole completions where the sand control screen directly retains the formation sand, proper screen selection is necessary to provide optimum life and minimum sand passing. Several screen sizing selection criteria are available in the literature such as Saucier, Coberly, Schwartz and others. However, these rules may not always be applicable, especially when premium screens, with metal meshes are used. These screens may use multi layers of wire mesh and its complex shaped pore opening may result in retention performance quite different from wire wrap screen slots.
Experimental work has been done on a very fine (d50=115–130 µm) uniform (uniformity coefficient=d40/d90=3) and a non-uniform (uniformity coefficient=ca 7) sands on a series of commercial screens segments. These screens include standard wire wrap and also premium grade screens. The testing consisted of pressure drop measurements and sand retention while the screen is subjected to a fluidized stream of sand. Analysis of the data provides a method of measuring screen performance during and after filter cake bridging/building. Utilizing this data, screen performance, i.e. comparative lifetime and sand passing can be projected based on a maximum a pressure drop across the screen assembly. This analysis method is applicable for any type of screen and formation.
Where possible, the results from the experimental tests are compared to prior literature screen selection methods. Graphs of the normalized data allow for a logical selection of the appropriate screen for a given formation sand.
A new procedure for the selection of production screens applicable to any formation
A comparison of the new method with prior literature methods
A comparison of performance of wire wrapped screens and premium screens.
Open hole completions in oil/gas wells have been common practice for the past several years. These wells have generally been long horizontal wells. The many problems and difficulties to get successful completions has been well documented, as many operators have been disappointed with the results.
It is now recognized that a successful horizontal open hole completion requires careful analysis of many factors. These are often dependent variables since a selection of a technology or method for either the drilling or completion may limit the use to only a few other interrelated products and services.
One of the key factors is to evaluate what type of screen technology may be necessary for sand control. The reservoir conditions usually dictate whether sand control is needed and greatly influence whether the applied technology can be successful.
When direct retention of reservoir sands is the likely completion scenario, a good understanding of the capabilities of the various types of screen technology is required. This includes the screen's capabilities to retain the formation sands, and its sensitivity to drill-in-solids based on the optimum drilling fluids, and well completion cleaning additives and methods that may be utilized.