Integrated Cemented Inflow-Control-Device System Design
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Off-bottom-cementing (OBC) operations are unique to Saudi Arabia and represent a very challenging approach to drilling and workover operations when deployed in combination with inflow-control devices (ICDs) across horizontal sections. The multitasking-valve (MTV) feature in upgraded ICDs offers safe, simple, and cost-effective deployment operations. This paper discusses the first deployment of an ICD system combined with an OBC system for a workover operation in a mature producer well in the Kingdom of Saudi Arabia.
In wells where an OBC liner is required to cover nontargeted formations above the production zone, two methods of deployment can be used: the one-trip system and the two-trip system. These refer, respectively, to whether the OBC components are deployed in a single trip along with the ICD or in a second trip with string in the previously deployed ICD completion. The one-trip OBC ICD completion does not allow an inner-string application. Therefore, circulation while running in hole was ineffective in this producer, which caused deployment problems
The two-trip OBC ICD completion was then considered. The idea was to split the completion into a lower ICD completion, which is dropped off inside the openhole horizontal section with a setting sleeve. The earlier two-trip OBC ICD completion used an inner string, a circulating system, and an openhole-packer-setting tool. This allowed 100% circulation from the shoe during deployment of the lower ICD completion, although circulation rate is limited because of pumping through the small internal diameter (ID).
The upgraded ICD with an MTV allows the lower completion to be deployed without an inner string while achieving 100% circulation at the shoe, which smooths operations and saves up to 24 hours of rig time. The MTV temporarily blocks the communication between string and annulus while running in hole. Once reaching the setting depth, MTVs are actuated by hydraulic pressure. All hydraulically set equipment can also be set at this point.
Ultimately, in the case outlined in the complete paper, it was decided to combine once again the separated deployment into a single system by use of the MTV feature, which provides important functions for the one-trip OBC ICD completion—the ability to perform 100% circulation from the shoe and to set all hydraulic downhole tools with one setting ball.
As shown in Fig. 1, the integrated system eliminates the seal assembly and setting sleeve. The float collar is also removed to give passage for the setting ball to land on the wellbore-isolation valve (WIV) located near the end of the completion string, above the float shoe. The nonshear-ball-seat position is moved below the cementing valve, providing a cement barrier from inside after dropping a second ball. The nonshear-ball-seat ID was enlarged to accommodate the 1.25-in. setting ball passing through while still being able to hold the 1.5-in. ball for a cement barrier.
Field-Trial Summary and Result
The well chosen for deploying the first integrated one-trip OBC ICD completion is a somewhat historic one in Saudi Arabia. The discovery well of the world’s largest field was drilled in July 1948 as an exploration well with a 7-in. casing. After a successful perforation job, the well was converted to an oil producer and completed with 2⅞-in. tubing. A 7-in. downhole packer with 3½- and 4½-in. tubing was set during the first workover that took place in July 1973 to replace the corroded 2⅞-in. tubing. The well was kept in production until mid-2012, when high tubing/casing-annulus (TCA) pressure was observed along with a water-cut increase. A workover operation was proposed to contend with the high TCA pressure and sidetrack the well to restore its productivity.
Re-entering a well drilled approximately 65 years ago was a challenge, and deploying the integrated system for the first time worldwide made it an important job. In the last quarter of 2013, the workover operation was commenced by killing the well. The well was decompleted and the main bore was plugged back to the whipstock-setting depth. A window was opened, and a 6⅛-in. hole was drilled to target depth, with approximately 3,000 ft drilled horizontally. Before running the integrated downhole completion, a stiff reaming assembly was run to clean out any tight spots and a wiper trip was performed to confirm that the directional hole was in good condition. A lubricant pill was spotted, and the stiff reaming assembly was pulled out of the hole.
The proposed completion, which consisted of a WIV, nine ICDs with MTV, four mechanical openhole packers, and five small swell packers plus the OBC line system kit, was picked up, drifted, and labeled. Getting this completion to the target depth across more than 5,000 ft of open hole in an area known for differential sticking was a major concern because any delay could lead to a stuck completion. Reducing the connection time between stands, filling the string using a hose during running in hole, and using special centralizers that have a lower friction factor were the main steps in getting the completion to target depth.
Completion equipment reached target depth after 18 hours. The hole was circulated clean at 3 bbl/min at 450 psi, and was displaced to brine. A biochemical mud treatment was pumped to be spotted across the ICD completion. A 1.25‑in. setting ball was dropped and chased with a high-viscosity pill and brine.
The ball landed at the WIV, and pump pressure was increased to 1,600 psi to set the liner hanger. The hanger was set and confirmed with 20,000-lbf slackoff. Pressure was increased to 2,000 psi to set the inflatable packers. Pressure was then brought up to 2,800 psi to set the mechanical openhole packer, actuate the MTV, and release the hydraulic liner-hanger-setting tool. The liner-hanger-setting-tool release was confirmed by pickup. Running string was slacked off 20,000 lbf, and pressure was increased to 3,100 psi, opening the cementing valve. Circulation was regained through the cementing valve. A second ball (1.5‑in. outer diameter) was dropped and chased the high-viscosity pill as a marker. The hole was displaced back to mud, and the marker pill showed at the surface, confirming that circulation was coming through the cementing valve.
Before the cementing job, a surface cementing line was tested to 4,000 psi, while 60 bbl of cement was mixed. The cementing job began by pumping a spacer followed by cement slurry. A dart plug was dropped and displaced with a spacer, followed by mud, then by the spacer, and finally by mud. Once the plug landed on the cementing valve, pressure was increased to 1,000 psi above the 700‑psi flowing drillpipe pressure. There was no backflow, which confirmed that the cementing valve was closed. The liner-top packer was set, the running tool was strung out of the liner-top packer, and reverse circulation was performed to clean out the spacer and contaminated cement. The running tool was pulled out of hole, and the job was completed. After the cementing plug and nonshear ball seat were drilled out, 320 ft of contaminated cement was found below the nonshear ball seat. The first ICD was located 400 ft below the nonshear ball seat.
Comparison and Gained Value
Three wells were drilled and completed by the same rig. As detailed in Figs. 6 and 7 of the complete paper, the OBC single trip with MTV eliminated all the operating time required with regard to the inner string and the setting of the openhole packers with an inflation tool, and the run-in-hole time for the second-trip OBC. For the mud treatment, pumping time was reduced significantly.
To have the ability to seal the ICD completion from cement in the string, a dual-cementing valve is being developed. The lower port of the dual-cementing valve will be opened by pressure against the WIV. After regaining circulation through the port, the first plug will be dropped. This plug will close the lower port while providing positive isolation for the ICD completion against cement intrusion from inside the completion string. The dual-cementing-valve upper port will be opened by pressure against the first plug, which will provide the path for cementing. Once cement is pumped, a second plug will be dropped and the upper port will be closed.
- The integrated OBC ICD completion successfully optimized well delivery by eliminating almost 40 hours of rig operating time.
- The MTV on the ICD plays a major role, allowing all hydraulic actuation and setting at once.
- The current system has the limitation of not having a positive indication for the second ball to land on the nonshear ball seat as a second barrier, which could result in cement invading the lower completion.
- Future development of the dual-cementing valve will provide positive isolation for the ICD completion from the cement inside the completion string.
Integrated Cemented Inflow-Control-Device System Design
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