Sand Control Mechanism Analysis of Metallic Wool Screen

Abstract A new sand control device, metallic wools screen, is developed to achieved a good effect on thermal and unconsolidated sand oil well. In this paper, an unique mechanism of sand prevention is explained according to its structure, this device is a filter pre-packed metallic wools in substance. A reliable "external cake" during production. The "external cake" is a key to control the particle exclusion of sand from production system, direct interception, hydrodynamic force are the primary capture mechanism of sand. Influence factors (particle characteristics, fluid properties, environmental conditions and filtering characteristics of metallic wools screen) on sand control are discussed. Based on the filtering equation, migration and deposition of sand grain invaded the device are modeled, too. Lastly, a part of experiment results are given, and effect of factors is briefly analyzed. These work provides a basis for correctly selecting parameters of sand control and designing the metallic wools screen. Introduction Well sanding is a phenomena of sand flowing through the formation, and it is a frequently encountered production problem in the thermal and unconsolidated sand reservoirs. Since oil is produced in large-scale, well sanding has become a difficult problem which puzzles the completion engineers & production engineers. All over the world, a great progress has been made by engineers' much efforts. Many technologies for sand control have applied in the oil fields, the main include slotted screen, gravel pack, chemical method, and so on[1]. They have a respective adaptability for sand control in oil fields. Therefore, they cannot completely meet the needs of the oil production, although they have played an enormous impetus role for the development of petroleum industry. With paying a great attention to exploitation of heavy oil reservoir in recent years, sand control becomes an outstanding problem. In the heavy oil well with steam injection, sand particle passes through and produced easily because the matrix is eroded and the asphalt or land paraffin is dissolved by the steam and the fluid with high viscosity flows through the formation. This brings about many complicated production problems, such as high cost associated with well servicing, considerable reduction of oil production due to unpredictable and serious formation damage[2]. Thus, sand prevention has become a emergency, but the previous methods cannot meet the needs of oil production very much. Therefore, a new sand control device, metallic wools screen, is developed, and it is composed of two pieces of filtration metallic clothes and a layer of metallic wool pre-packed into the clothes. Now, it has applied in oil fields successfully, it's specific properties are as follows:High mechanical strength, anti-high temperature & corrosion and long work life;High porosity and excellent permeabilitySimple structure, easy operation and good adaptabilityLowcost PRINCIPLE OF SAND CONTROL The principle of sand control for the metallic wools screen is quite different from the other devices. Sand is prevented from by filtration of outside screen cloth and adsorption of middle wools layer.