In cost-constrained market, holistic approach to cementing is essential
New-generation spacer system enables successful cement jobs on Colombia’s Guatiquia field and in Gulf of Mexico well with presence of salt and H2S
By Linda Hsieh, Editor & Publisher; and Sarah Junek, Associate Editor
In a market characterized by continuing price fluctuations and cost constraints, Baker Hughes, a GE company, has identified standardization, simplification and efficiency as the three cornerstones driving its cementing strategy. This means that it’s more important than ever to take a holistic approach to cement jobs, said Deepak Khatri, BHGE Director of Cementing.
“When you look at something from only one angle or two, it’s very easy to miss something,” Mr Khatri said. “But when you look at a cement job holistically, you look at everything from simulations to providing the right spacer to slurry system customization. And we do evaluation after the job so that we capture lessons learned.”
To optimize the removal of drilling fluids and placement of cement, BHGE introduced a new version of its SealBond cement spacer system in 2018. Compared with the previous generation, the new SealBond Ultra can provide nearly double the sealing and plugging capability, according to BHGE.
The system is based on the company’s ultra-low invasion fluid technology; it forms a barrier at the wellbore wall to strengthen the wellbore, minimizing filtrate invasion and damage, as well as induced losses. The technology can seal natural fractures as large as 1 mm. “Our goal is to make sure that when we pump our fluid system, that will seal any permeable zones, so the objective of complete returns of fluids is accomplished,” Mr Khatri said.
In wells with low fracture gradients, using the system also means that the operator can deploy standard slurry designs and densities, instead of having to switch to lightweight slurries.
One of the first field implementations of the new system was conducted last year in a highly permeable onshore formation in Colombia’s Guatiquia field.
“The challenge was the operator was not able to lift the cement to the desired depth in previous wells,” Mr Khatri said.
To minimize the risks of downhole losses before running the production liner on the next well, BHGE reviewed cement evaluation logs on previous wells and determined that cementing was affected in front of a highly permeable formation. It then used the CemFACTS software for pre-job design, real-time simulation and post-job analysis.
“The latest version of this software takes into consideration depth, hole size, deviation, desired pump rate, bottomhole temperatures and pressures, and other inputs, and then it simulates in a holistic way to ensure that the cementing spacers and slurry are placed at the right rate and depth,” Mr Khatri said.
The simulation resulting from this software also factors in fluid complexity, so “we’ll take compressibility into consideration so we can compensate with the right volume and ensure that displacements are accurate.”
The first job in Colombia was a success, with the production liner operation executed as planned and excellent fluid returns achieved. Proper cementing was verified with cement logs.
Because of this success, the operator then awarded BHGE with all of its production liner cementing jobs in all future wells on this field; 11 wells have been completed to date. “Since then, we’ve had tremendous success in the UAE, Indonesia, Kuwait, Mexico, Bolivia and, most recently, in the Gulf of Mexico (GOM).”
Early this year, the new spacer system was used in a GOM project that ultimately saved the operator three days of rig time, or approximately $1.7 million.
While running a 7-in. production casing, the operator drilled through a salt formation and weak sand, resulting in pack-off, mud losses and wellbore erosion. A total of 473 barrels of synthetic-based mud was lost while drilling through this salt zone, after lost-circulation material was run and returns were established.
Then, while running the casing, an additional 119 barrels of mud were lost.
The operator had encountered a similar situation on an offset well, and a remediation block squeeze had to be performed in that case. To prevent the need for such remediation on this well, BHGE deployed SealBond Ultra to minimize fluid leak-off to the formation.
Because of the mud properties of the well and the presence of salt and H2S in the target hydrocarbon interval, a spacer design using 18 lb/bbl of Sealbond Ultra concentrate with 7 lb/bbl KCl was selected. A total of 60 bbl of the spacer, with KCl at 12.5 ppg, was used to attain the minimum 1,000 ft of fill while being pumped through the open-hole interval.
At this point, BHGE also deployed proprietary software to determine optimal displacement rates for equivalent circulating densities below the fracture gradient.
Cement bond logs were run to verify top of cement and isolation of the hydrocarbon-bearing sands.
BHGE is now planning for jobs with the new cement spacer system in Thailand and Saudi Arabia. DC
