Abstract
Operator planned to develop the new low-permeable sandstone gas reservoir below the mature gas layer in Ordos basin. In terms of cost reduction the wellbore was designed to pass through the undeveloped resource locating in the upper mature reservoir to obtain dual-zone commingled production. According to the well logging, there was the indication of hole collapse, enlargement and an unforseen water bearing zone found in the deviated section locating in upper zone. Packers could fail in the irregular deviated wellbore.
Upon the modification of completion solution, the 4 1/2in open-hole packer-sleeve (OHPS) completion and fracturing system was deployed to treat the lower target zone. Top cementing operation using novel stage collar with swellable elements was performed to isolate the upper mature zone. "Plug and Perf" (PnP) via compact bridge plugs was carried out to enable efficient fracturing in deviated wellbore. The single-trip OHPS system employed water-swellable packers (WSPs) with corrugated packing element.
The WSP and compact bridge plug were successfully evaluated by bench test. In one gas well, the operator performed cementing job and the stage collar was opened by wiper plug once the tripping of the OHPS completion with five packers was made successfully. Three bridge plugs were pumped down to the target depth. Hydraulic fracturing operation was sequentially made with all packers and bridge plugs effectively set. It is shown from the field operation that the hybrid completion is able to meet the requirements of completion and stimulation in irregular wellbore with abnormal conditions for tight reservoirs.
