Effective elimination of unwanted solids from the production stream is a key element of production optimization, and one that requires an engineered approach.
PetSec Energy Inc., a large, growing independent in the Gulf of Mexico, recently developed three monobore wells in its West Cameron 352 field offshore Louisiana. This mature field with existing completions also containsnewly drilled secondary targets primarily consisting of high permeability gas formations. Hydrocarbons in this field are located in fault trap reservoirs and are pressurized and produced by a water-drive mechanism.
The challenge was to develop a cost-effective well system compatible with multiple, high-rate, sand-controlled completions for stacked pay intervals. Since the three prospects hadlimited reserve potential, conventional drilling and completion methods would not be feasible. At the same time, any rigless completion method ultimately selected would have to be economical compared to current rig rates. It would also need to involve minimal mechanical risk and maintain the best practices developed for sand-control completions in the area. A new service from Halliburton calledCrimson Vent Screen (VS) was chosen.
This service was developed to make bypassed reserves economically viable by matching the proper vent screen assembly design, conveyance mechanism and sand-control method with overall project coordination. As a total engineered rigless solution, the service would be able to withstand the maximum anticipated production rates which were determined through anadvanced modeling system that incorporates the well parameters and well deliverability to determine vent screen completion stability.
Traditional sand control
Vent screen or dual screen technology was introduced in the late 1980s and is now a commonly accepted completion strategy. Vent screen assemblies consist of a primary production screen long enough to cover the perforations, a length ofblank spacer pipe, and a short upper section of screen bull plugged on top. Using vent screens allows subsequent completions of payzones up hole to be performed more cheaply since no production tubing has to be removed to run additional sand control assemblies. Additionally, predicting and modeling vent screen completions through correlations and simulators developed in both field experience andlaboratory experiments have increased the success rate of vent screen completions to a level equivalent to other sand control/stimulation treatment strategies.
The technique typically employs two screen assemblies separated by blank pipes that are placed and packed in casing. The screen and blank assembly are then run into the hole through the production tubing, using electric line, slickline, orcoiled tubing and are set on bottom. Following that, the sand control treatment, consisting of a gravel pack or high-rate water pack, is emplaced at the desired rate. At the end of the treatment, proppant is allowed to pack into the screen and the blank annulus. Production enters the lower screen section and exits the upper screen section. This method is traditionally applied only to low-reserve,cost-sensitive reservoirs, or as a last-ditch effort to control sand and production in old wells.
A new chapter in sand control
Crimson VS completion service uses recent innovations in coiled-tubing and sand-control technologies to enable rigless through-tubing vent screen sand-control completions for both initial and alternative remedial completions. The service combines Antifluidization(AF) screen technology, real-time coiled tubing depth-measurement tools, and advanced proppant delivery systems. The results increase the operating envelope for vent screen through-tubing sand control technology, allowing wells to produce at rates higher than 50 MMcf/d of gas or 10,000 b/d of oil. Typical through-tubing completion candidates are identified as gas wells with three to five BCF of...