Expandable sand screens have been around for some time, but new designs feature mechanical integrity that is key to their post-expansion screenability benefits.

Mechanical integrity was the primary consideration in developing an expandable sand control system that could function as a viable alternative to gravel packing in horizontal openhole wells. The result was the EXPress Expandable Sand Control Screen from Baker Oil Tools, which has allowed zero sand production since its introduction in 2001.

The Express screen was designed to combine premium sand exclusion with downhole outside diameter and inside diameter expandability for enhanced wellbore stability. To accomplish this dual objective, a patented design founded on solid, perforated base pipe was used, along with a proprietary threaded connection and filter membrane construction (Figure 1). The mechanical structure of the perforated pipe design offers superior collapse resistance when compared to slotted configurations. Such collapse resistance is particularly advantageous in providing long-term wellbore stability in unconsolidated, dilatant (reactive clay/shale) formations and "dirty" (i.e., not clean and homogeneous) sand structures. The proprietary threaded connection provides superior torque and high tensile strength and compression resistance that protect the screen during installation. It also allows thread make-up in a timely manner.
Sand exclusion media are wrapped around the perforated blank pipe: a drainage layer, filter membrane and drainage enhancement layer. The filter membrane construction is the same as that used in Baker's EXCLUDER and EXCLUDER2000 sand screens. The filter membrane allows mud solids to be produced without plugging the screen. It provides an inflow area that is comparable to the formation face. The dual-weave filtration enhancement layer improves particle holding ability. The weave media is covered in a perforated, protective shroud for enhanced installation reliability.

Weave selection is based on sized solids-conditioned mud and formation sand flow tests, with hole pattern and size optimized for maximum opening area. The weave pore-through remains relatively constant throughout the entire range of expansion (Figure 2). This pore-through width determines the glass bead size that will pass through the filtration media. As part of Baker's expandable well services, onsite QA/QC testing is conducted to determine compatibility of fluid flowback through the expanded screens.

Expandable sand control completion system

Expandable screens feature a much larger external and internal diameter than other standard screen designs and reduce produced fluid pressure drop, resulting in enhanced inflow profiles along their lateral length. Field application and production history indicate significantly greater productivity indexes than with comparable offset wells in the same reservoir. Additionally, the resultant larger external and internal diameters provide opportunities to install flow control completion equipment and a host of improved remedial options not available in smaller tubing.

A top-down, hydraulic expansion system known as catEXX, is employed that enables systems to readily expand into extremely deviated and horizontal wells in a single trip. Hydraulic pressure anchors the expansion system in place and opens a piston, which progressively pushes an expansion cone through the completion assembly to set the liner hanger, expand the solid pipe, set the isolation packer and expand the screen. After the expansion process is complete, the catEXX system is retrieved from the well.
Expansion flexibility is enhanced by the option of using a fixed or adjustable cone. The adjustable cone provides additional expansion capabilities in order to expand through tight spots or overexpansion into out-of-gauge hole sections for improved borehole stability in very fine formations (Figure 3). The variable and fixed cone options bring additional benefit to an expandable sand control system designed to enhance productivity and reliability in challenging formations.

When the EXPress screen is expanded, "off-the-shelf" completion assemblies as well as multilateral and intelligent completion systems can be installed through it to provide closed-hole zonal isolation and selective production in open hole. Figure 4 shows the layout of the world's first completion set inside an expandable system. This project, in the Attaka field offshore East Kalimantan, Indonesia, created a single selective well that allowed the operator to selectively produce or commingle from different zones. The completion was configured using a combination of EXPress screens, EXPress blank pipe, CMD sliding sleeves, FORMpac XL openhole isolation packers and the FORMlock Express liner hanger.
EXPress expandable completion systems provide bottomhole assembly component modularity that can efficiently address unexpected openhole log issues such as longer productive intervals, dipping into a water zone, or extensive shale sections with appropriate space-out to match the log data analysis. Screen lengths can be extended to capture more interval or isolation packers and blank pipe rearranged to isolate water and/or shale sections.

An alternative to openhole gravel packs

The primary objective of any completion design is to deliver a well that will safely maximize productivity and longevity until the hydrocarbon resource is depleted. How the well is drilled and completed initially impacts its long-term performance. Drilling and completing horizontal openhole wells using state-of-the-art procedures and technologies such as expandables can have a significant positive effect on well profitability.

Maintaining borehole stability during the drilling and completion phase is an essential requirement for any openhole completion but particularly for openhole unconsolidated, dilatant formations. Fortunately, state-of-the art drill-in fluids and specialized procedures can help maintain borehole stability while drilling and completing in dilatant-type formations known to present problems.

For openhole completions that require sand control, properly displacing the well prior to running screen may mean the difference between a well that will produce at the reservoir capacity and one that is completion-limited as a consequence of premature plugging from dirty sand or unstable hole. Removing excess solids and filtrate from the open hole is believed to be vital to the success of the well. Openhole displacement procedures for gravel packs may be more complicated than expandable screen applications. Openhole gravel packs require that the drill-in fluid in the open hole be displaced to a fluid compatible with the gravel carrier fluid (generally brine based), whereas expanding screen applications may be run in a sized-solids-conditioned or solids-free drilling or drill-in fluid (oil based or water based mud).

Expandable systems have been successfully deployed in unconsolidated formations for horizontal openhole sand control completions. An important feature of these completions is their ability to provide improved zonal isolation by significantly reducing or eliminating the screen-to-openhole annulus axial flow component. Unlike stand-alone screens or gravel packs with incomplete pack placement, expandable sand control completions minimize dynamic sorting of mobilized formation and occurrences of premature screen plugging and/or erosion (Figure 5).

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