Achieving High-Rate Completions With Innovative Through-Tubing Sand Control
- Thomas A. Bell Jr. (Conoco Inc.) | Dan W. Morrison (Halliburton Energy Services) | William E. Martch Jr. (Halliburton Energy Services)
- Document ID
- Society of Petroleum Engineers
- SPE Drilling & Completion
- Publication Date
- March 2002
- Document Type
- Journal Paper
- 49 - 53
- 2002. Society of Petroleum Engineers
- 4.1.2 Separation and Treating, 2.2.2 Perforating, 3.3.1 Production Logging, 5.5 Reservoir Simulation, 1.10 Drilling Equipment, 5.7 Reserves Evaluation, 1.8 Formation Damage, 3 Production and Well Operations, 5.6.1 Open hole/cased hole log analysis, 5.2.1 Phase Behavior and PVT Measurements, 1.4.3 Fines Migration, 5.1.1 Exploration, Development, Structural Geology, 2.4.6 Frac and Pack, 2.4.5 Gravel pack design & evaluation, 3.2.5 Produced Sand / Solids Management and Control, 2 Well Completion, 2.4.3 Sand/Solids Control, 1.14 Casing and Cementing, 5.6.4 Drillstem/Well Testing, 2.5.2 Fracturing Materials (Fluids, Proppant), 4.1.5 Processing Equipment, 5.1.2 Faults and Fracture Characterisation, 1.6 Drilling Operations
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Recently, an improved through-tubing sand-control technique was used to enhance reservoir recovery and improve the life-cycle economics of an offshore well in the Gulf of Mexico. This coiled-tubing- conveyed method used several technical innovations to improve the reliability of the vent-screen sand-control completion. The two most important technologies in the system are a coiled-tubing wireless depth-correlation device and a new surface modification agent (SMA) for the proppant/sand. These innovations can improve reserve recovery rate and completion efficiency, reduce mechanical risk and completion costs, extend the economic life of the well, and control fines migration.
The Ewing Bank 305 field is located approximately 100 miles south-west of New Orleans. The current strategy for this field is to develop deep oil reserves and exploit shallow gas reservoirs. The hydrocarbons located in fault-trap reservoirs are normally pressured and produced by a waterdrive mechanism.
In the past, the wells were completed conventionally with circulating gravel packs, generally with a dual-completion configuration. In the mid-1990s, a single-completion strategy with 3 1/2-in. production tubing was adopted to increase production rates from new wells. The current program continues to employ gravel-packed completions with larger, 3 1/2-in., single-production strings. In addition, because many of the new wells cut multiple pays, a completion configuration is used to provide an initial conventional gravel-packed completion and through-tubing access so that future recompletions can be performed without rig intervention. For example, the packer and tubing do not need to be pulled from the well with a rig to perform the recompletion on the next zone of interest. Rather, coiled tubing and/or electric line can be used to perform the next zone change by means of a platform or jackup boat. Future recompletions can be executed with or without gravel packs, depending on the best economic value. If no screens are installed, production rates may be limited to prevent the onset of sand production by controlling the amount of pressure drop across the perforations. In the past, through-tubing screens were deployed in the tailpipe below the packer with a packoff or lock to suspend the screen assemblies. These methods, however, do not permit uphole recompletions because they are expensive and risky to recover from the well. The vent-screen method is effective for rigless sand control while providing future recompletion options for shallower zones without the need for a rig.
Extensive time and effort are devoted to optimizing each completion in the reservoir. Because of the rapid depletion of these faulted reservoirs, control of completion costs is critical to the economic success of each well. In considering which rigless completion method to use at Ewing Bank 305, it was critical that the process be economical compared to current rig rates, afford minimal mechanical risk, and not sacrifice the best practices developed for sand-control completions in the area.
Vent-Screen Completion Method
The vent-screen, or dual-screen, sand-control method has been used for many years in situations requiring remedial sand control. The vent-screen technique uses two screen assemblies separated by blank pipes that are placed and packed in casing. Production enters the lower screen section and exits the upper screen section.
The screen and blank assembly are run into the hole through the production tubing on electric line (e-line), slickline, or coiled tubing and set on the bottom. The sand-control treatment, consisting of a gravel pack or high-rate water pack, is placed at the desired rate. At the end of the treatment, gravel is allowed to pack in the screen and the blank annulus (see Fig. 1).
This method is generally applied only to low-reserve, costsensitive reservoirs, or as a last-ditch effort to control sand production in old wells. However, recent innovations in coiled-tubing and sand-control technologies enable rigless through-tubing, ventscreen, sand-control completions for both initial and alternative remedial completions.
Typical through-tubing completion candidates are identified as wells with 3 to 5 billion ft3 of reserves, stacked pays, high rig costs, and intervals with a 6- to 12-month productive life in each zone. This completion technique has two limitations - a lack of access to the zone and the production logs for future formation and the inability to selectively treat the perforated interval. The economic restraints of the individual zones in a well dictate the need for remedial work. Most of the wells that employ this completion method are plugged back to the next zone as soon as the completion fails, and production and/or formation logs are not needed because of the limited reserve size.
Table 1 illustrates 12 case histories, including production data, of wells in the Gulf of Mexico that met the previous criteria and were completed by the rigless sand-control method. This paper proposes three levels of rigless sand-control completion.
The most advanced level incorporates the technique in the initial completion design. Wells with multiple, stacked pays are ideal for this method because it allows multiple workovers without mobilization of a drilling or workover rig.
The second level is reserved for recompletion of pre-existing wellbores that have accessible pay below the production packer.
The last level is reserved for remedial sand control in currently existing wellbores in which no sand-control screens have been installed.
Any of these cases can use preferred fracture-enhanced, sandcontrol pumping methods; fracture-enhanced gravel pack (FEGP); or frac-pack.
Rigless Single-Trip Vent-Screen Completion
In the rigless, single-trip, vent-screen completion method, coiled tubing is used to perform all completion operations. In this case history, the coiled-tubing-conveyed casing collar locator (CTCCL) was used to correlate with an existing gamma ray (GR)/CCL for depth control. The lower depleted interval was plugged by setting a cement retainer and squeezing. The pipe and depth were marked before pulling out of the well.
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