For Stand Alone Screen (SAS) completions in open hole oil/gas wells, the sand control screen must retain the formation sand effectively, and provide a conduit for fluids to flow into a producing well. The screen's performance and service life depends on the well's operating conditions. A failure may occur while completing the well, or at some time during the well's operating life. The root cause of the screen failure is often difficult to determine with absolute accuracy. Often, it is determined that screen failure occurs due to a combination of plugging and erosion resulting in the loss of sand control. A comprehensive test program was undertaken over a two year period to evaluate erosion of different screen types for open hole completions. Completions were simulated for wire wrap and metal mesh sand screens commonly used in open hole completions. Configurations of each screen type were installed in a test fixture, and several tests were conducted at different velocities and sand concentrations. The sand was sized to pass through the screen with minimal plugging, which would simulate fines production over time in a producing well. The specific wear rates and per cent of rate loss were determined for each test. Micro photos were used in the analysis of the wear patterns, along with pre and post test measurements of the wire wrap slots or metal mesh pore sizes. This paper will describe the test methods used, the test results and lessons learned, and will describe a model that can be used to predict a screen's service life based on a given set of well conditions in a SAS open hole completion. Introduction Sand screens are often used to provide sand control in open hole completions. A common completion method is a stand alone screen (SAS) where by the screen aperture is sized to directly retain the formation sand. A typical completion is shown in Figure 1.

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. Technical Contribution:A new procedure for the selection of production screens applicable to any formationA comparison of the new method with prior literature methodsA comparison of performance of wire wrapped screens and premium screens. Introduction 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.

Stand-alone screens are often a simple and cost-effective sand control solution for long, multi-zone openhole completions. A recent technology advancement is a self-mitigating MazeFlo™ screen for enhanced sand screen reliability. Redundant screens and compartment mazes are incorporated to capture local sand ingress caused by screen damage without interrupting the overall well production. A common screen damage mechanism is screen erosion. The new screen extends the production capacity by increasing erosion resistance and providing self-mitigating functionality. A self-mitigating screen includes an outer primary and an enclosed offset inner secondary screen. A maze compartment stands between the two screens to enable self-mitigation of screen damage. Without the primary screen damage, the secondary screen must withstand continuous fines production to maintain sand control capability in the well. If the primary screen is damaged, the erosive sand will enter the maze compartment and deposit on the secondary screen. The integrity of the maze compartment must be maintained until the compartment is fully packed and the well production is diverted to adjacent undamaged screens. This paper discusses a methodology to evaluate the erosion resistance with regard to operating conditions in a self-mitigating screen. The methodology includes a suite of laboratory tests to establish an erosion baseline for a wire-wrapped screen. The erosion baseline, along with fluid flow modeling will provide design guidelines for a given operating condition. A proper MazeFlo screen design sustains the self-mitigation capability throughout the life of the well. The design envelope can be further expanded when combined with other technologies such as zonal isolation and inflow control devices.

This paper describes challenges, test equipment, test program and results in the development of a screen product and contingency fluid-loss control (FLC) pill formulation to withstand 4,600-psi burst resistance pressure. In maturing deepwater fields, such as Shell Ursa/Princess where depleted reservoir pressures are significantly below the hydrostatic pressure of a seawater column, a modified screen design was required since screen products currently available were limited to <3,500 psi. FLC pill formulations also required modification because they were only validated to 1,000 psi in the current laboratory test apparatus. A series of burst tests were conducted on a wire-wrap screen design direct wrapped to 4-in. base pipe. The objective was to determine if the screen could withstand at least 4,600 psi without damage. The wire-wrap design selected to improve the pressure rating was substantially heavier than what has been used in traditional sand-control completions. Initial burst tests with available 316L material averaged 4,600 psi. Two sets of additional burst tests were conducted with Alloy 625 screens on 25 Chrome base pipe to meet injector material requirements. The FLC formulation was modified from conventional design to enhance the pressure response. The last test results averaged over 5,100 psi. Comprehensive before and after measurements and slot inspections were done; the data were used in Finite Element Analysis to finalize the detailed screen design. No traditional mechanical burst of the screen occurred. Most influential factors were slot size/geometry and pill formulation. Introduction Ursa-Princess Waterflood Development Overview The Ursa and Princess Fields, brought online in 1999 and 2003 respectively, are part of the Mars basin located in the Mississippi Canyon area, offshore Louisiana, Gulf of Mexico, in 3,850 ft of water (Figure 1). The primary producing interval in both fields consists of an unconsolidated, turbidite amalgamated sheet sand with evidence of pressure communication through the hydrocarbon leg. Aquifer support does not exist within this sand; instead the primary recovery mechanisms are depletion drive and compaction. This lack of pressure support led the operator to develop plans for four high-rate subsea water injection wells (two in the Princess field and two in the Ursa field) to enhance production in the main producing sand. Eight direct vertical access wells from the Ursa TLP and three subsea Princess Wells will directly benefit from the planned water flood. The current lack of pressure support in the reservoir sand results in relatively low recovery efficiencies. Under the proposed development plan, the four injectors are expected to maintain higher pressures and improve sweep efficiency, ultimately resulting in significant incremental recovery.

Sand screens subjected to increasingly complex and challenging environments are pushed to the limit of maintaining reliable sand control. Both preventive and reactive methods have considerably improved sand screen reliability, but the effectiveness of these methods in sustaining production is still limited by downhole uncertainties. Consequently, innovative sand screens are required to enhance sand control reliability, while maintaining operational simplicity. MazeFlo™ is one recent technology innovation from ExxonMobil designed to meet this challenge. MazeFlo technology takes a self-adapting approach to enhance sand screen reliability. The technology utilizes a redundant sand screen and compartment maze to self-mitigate sand breakthrough caused by screen damage. The sand ingress is restricted in a local compartment without interrupting the overall well production. A 2?" prototype screen has been designed, fabricated, tested, and qualified for field installations. This paper will highlight the qualification of this new screen through a series of mechanical tests and concludes with a field test designed to subject the screens to an extreme producing environment. The mechanical performance was evaluated under various load bearing conditions including collapse, burst, bending, torsion, tension, compression, and push-off. The results proved that there were no constraints to the self-mitigating capability of this new screen when subjected to this rigorous testing program. The field qualification test was conducted in an existing sand-prone well producing at high local flux to demonstrate screen functionality in an "uncertain" production environment versus a controlled, laboratory experiment. The field test demonstrated successful installation, downhole self-mitigating capability, and sustained sand-free production. This unique, self-adapting technology unlocks the limits of sand screen reliability and provides an innovative and unique option for sand control completions to sustain production. The dedicated collaboration between operator and service supplier delivers continued success in developing innovative technology from concept to field installation.