Page 66: of Offshore Engineer Magazine (Sep/Oct 2013)

65 67

Typically the SRCT will be opened infow control devices or preventing perforated sections below. when clean completion fuid is dis- effcient setting of completion pack- The annular BOP was then closed placed to above the tool and friction ers. The emulsifed fuids then need and 1,500psi applied to confrm suc- in the liner is at its peak and there is a to be shipped to shore for treatment or cessful setting of the packer and SRCT.

Drilling requirement for increased AV’s in the disposal, which can impact operations The test demonstrated that the well- larger casing sections. due to rig space and shipping. bore below the packer was isolated up

Weatherford was called upon to help to the required pressure of 1,500psi. the operator to develop a cost-effective The annulus was then bled off and the

Preventing losses in North Sea wells

A North Sea operator had a history well cleaning solution that would avoid annular BOP opened. The Weatherford of fuid losses during circulating in these possibilities. This began with operator then set down weight on the several wells. As a result, the operator a preplanning meeting in which the SRCT, which sheared the activation could not achieve the desired circula- operator provided all relevant informa- ring to collapse the tool, disengage an tion rates to fully displace the well, tion for the next well to be drilled and integral clutch and open the circulat- resulting in a buildup of a water-in-oil completed using the new well clean- ing ports, allowing the mud condition- emulsion created from the mixing of ing strategy. Located at a water depth ing and displacement to commence water with the oil-base mud, which of 103m, the well was to be drilled to by circulating out of the SRCT and contained an emulsifer package. a measured depth of 4,550m and total rotating the string, without placing any

The addition of more water into the vertical depth of 2,889m. The plug back torque through the packer. emulsifed fuid increased its viscosity, total depth for the well was 3,846m and The displacement stage consisted causing further displacement chal- the bottomhole temperature was 114 °F. of pumping base oil as a lead spacer, lenges. If this emulsifed fuid is not Both the mud provider and Weatherford followed by a viscous pill, then a wash fully displaced out of the wellbore, it engineers prepared a hydraulic simu- pill, and fnally, clean brine. Once clean may cause problems for the comple- lation for the well, which estimated brine was observed returning to the tion, such as plugging up valves and that the maximum allowable ECD surface to signal complete displace- (equivalent circulating density) would ment, the drillstring was picked up to be exceeded when pumping at the close the SRCT ports, The ball seat on required rate to effectively circulate and the ISO-MAX security packer was then condition the mud system, resulting in sheared to allow communication from the well going on losses. drill string to annulus in the event that

Based on the simulation, any well control situations arose. The

Weatherford recommended the packer was released with overpull, and combined deployment of the security the entire assembly was then POOH packer and SRCT to isolate above without incident. perforations in the 9-5/8-in. casing sec- The operator was pleased with the tion of the well to prevent losses when packer and SRCT’s performance in circulating and subsequent formation fully isolating the lower wellbore and damage. A full schematic of the drill- effciently cleaning the well ahead of string confguration with the tools was subsequent completion operations, and developed and agreed to by the opera- recorded a savings of one day in rig tor, and the deployment was planned. time, roughly US$500,000. This job

After perforating the casing in the validated the potential of using this planned locations, cleanup runs with combination of tools in any openhole scrapers and magnets were performed application where losses are likely, and to remove debris and prepare the well- conditioning of mud or displacements bore to accept the packer and SRCT, are required. and subsequent completion.

The confguration of the wellbore Michael Ronson is a cleaning assembly consisted of a project manager for ported bullnose placed at the bottom of Weatherford in the drillstring, followed by the ISO- Norway, situated in

MAX packer and SRCT, and fnally, the Well Construction more drillstring to surface. group. He came to

The wellbore cleaning string was Weatherford in then RIH to the desired setting depth. February 2011, and has 10 years’

The selective rotation and circulation tool

The ball was then dropped and pres- experience in the oil and gas industry. (SRCT) is available in sure applied to set the packer, once the He has served in numerous rolls, standard sizes suitable ball had landed on seat. The ball was working in completion fuids, displace- for casing ranging from left in place throughout the operation ment chemicals, and mechanical 589-/in.-diameter and to provide complete isolation for the downhole tools disciplines.

up.

OE | September 2013 oedigital.com 68 000_OE0913_D&C3-Weatherford_Interv.indd 68 8/18/13 8:33 PM