CLAYSEAL PLUS shale stabilizer is used to inhibit hydration of reactive clays and shale formations. It iseffective in most water based drilling fluids from fresh water to high salinity brines and is suitable for use up to 400°F (204°C). CLAYSEAL PLUS shale stabilizer functions best at a pH range from 7 to 10, but is also effective in lime based fluids. CLAYSEAL PLUS shale stabilizer helps reduce the potential for bit balling and improves drill solids removal. When used with CLAYSEAL PLUS shale stabilizer, clay based viscosifiers should be prehydrated before addition to the active fluid system.
Applications / Functions
CLAYSEAL PLUS shale stabilizer can be used to inhibit clay and shale hydration
Advantages
- Helps reduce the potential for bit balling;
- Helps improve drill solids removal;
- Effective in fresh water, sea water, salt water, lime, and low solids systems;
- Is completely water soluble.
Typical Properties
Add 4-7 lb/bbl (11.4-20 kg/m3) of CLAYSEAL PLUS shale stabilizer.
Notes:
- For best results, a minimum of 4 lb/bbl (11.4 kg/m3) of CLAYSEAL PLUS shale stabilizer is required;
- Prehydrate all AQUAGEL? additions for viscosity and fluid loss before adding to system;
- Initial treatments in nondispersed systems may cause slight flocculation and may require a thinner.
Packaging
CLAYSEAL PLUS shale stabilizer is packaged in 5-gal (18.9-l) pails containing 41-lb (18.6-kg) net weight and in 55-gal (208-l) drums containing 459-lb (208-kg) net weight.
CLAYSEAL PLUS Shale Stabilizer Saves Operator US$150,000
OVERVIEW
While drilling in the Chichimene field, the operator continually encountered wellbore instability issues in the 12?-in. interval. The operator challenged the Halliburton Baroid team to provide a solution.
CHALLENGE
The operator’s wellbore instability issues included clay swelling, washout above shale intervals, and high MBT values (clay concentration) at the end of the section, resulting in prolonged tripping time, backreaming, and occasional stuck pipe incidents – adding up to 120 hours of nonproductive time.
SOLUTION
Before starting the project, Baroid engineers (including a Baroid Global Technical Advisor) performed in-depth analyses of information from offset wells, lab tests, operational practices, a geomechanical study, and operational results in prior drilling campaigns.
The Baroid team proposed and implemented a drilling fluid treated with CLAYSEAL PLUS shale stabilizer to provide effective inhibition. The team also worked with the operator to identify opportunities for improvement in operational practices.
RESULTS
The inhibitive CLAYSEAL PLUS water-based fluid delivered improvements in hole quality and better hole cleaning.
The operator observed a significant reduction in tripping time, down from 45 hours on previous wells. The estimated value in saved rig time was approximately US$150,000.
HYDRO-GUARD water-based drilling fluid system replaced competitor silicate mud, delivering stable wellbore through troublesome shale
Location: Namibia, Offshore West Africa
OPERATOR’S CHALLENGE
In planning an exploration well offshore West Africa, the operator specified use of an invert-emulsion drilling fluid. However, the requirement for an onshore mud plant and additional infrastructure needed, including transport to the remote location and special handling, caused challenges to deliver the fluids on time.
With the additional challenges involved in producing and transporting an invert emulsion fluid system in the required time, Baroid suggested the use of a high-performance water-based fluid system.
HALLIBURTON’S SOLUTION
Halliburton recommended use of HYDRO-GUARD? water-based fluid to deliver the rate of penetration (ROP) and the gauge hole the operator needed to drill the well successfully, while reducing nonproductive time (NPT).
After nearly four months of discussion covering every aspect of the project, the Halliburton team demonstrated HYDRO-GUARD fluid systems performance in previous offshore wells. Additionally, Halliburton demonstrated the infrastructure and logistical capability to deliver this solution within the tight project deadline.
To meet project requirements, the Baroid supply chain brought together the necessary chemicals from multiple global stock points and suppliers.
The HYDRO-GUARD fluid system was then used to drill a 17.5-inch section for 3,975 feet through a shale formation with outstanding results. The high-performance water-based fluid produced virtually no swelling in shale formation and, as a result, produced a gauge hole in the critical section with only 0.11% washout. Additionally, the section was drilled faster than the operator’s original time estimate based on the use of an invert-emulsion fluid.
ECONOMIC VALUE CREATED
By listening and responding to the customer’s needs, Baroid was able to deliver distinctive service quality with this successful debut of the HYDRO-GUARD water-based fluid system in West Africa. The system exceeded operators expectations, with no health, safety or environment incidents, ZERO NPT, and significant economic returns for the operator. Overall, the operator realized savings of about $700,000 in the cost of the mud, and an additional $2 million from not having to mobilize and pay rental on a mud plant.
In addition, Halliburton’s Supply Chain Manager and Logistics team successfully coordinated acquisition and timely delivery of all chemicals, cutting more than $500,000 from the original estimate through skillful management and attention to timing.
Environmental impact was reduced by utilizing this high performance water-based fluid system compared to an oil-based system. Waste treatment costs such as pit, tank, and rig cleaning, oil on cuttings treatment and waste discharge also helped further lower the operators liability and reduce costs by $1 million.
As a result of this success, the operator is now planning to use HYDRO-GUARD fluid in its upcoming offshore Angola campaign, in what will be the first use of a water-based fluid in the offshore Angola market.
Successful deepwater well drilled with high-performance HYDRO-GUARD? water-based mud avoids zero-discharge costs
Operator’s Challenge
The operator was concerned about the new zero-discharge regulation for offshore Angola and needed a high-performance water-based mud (WBM) to replace the oil-based muds (OBMs) traditionally used there. The challenges included reactive clay in the post-salt formation and extended lead times for materials. This operator had used the HYDRO-GUARD? WBM system in deepwater operations in Brazil.
Baroid technical personnel began testing formulations that could inhibit the shale in the post-salt formations, using also an offset well information in Namibia and a shale study run in the area. In order to meet the region’s toxicity testing requirements and zero-discharge specifications, the Baroid team replaced the CLAY GRABBER? shale stabilizer, a product normally used in HYDRO-GUARD systems, with the non-toxic EZ-MUD? DP clay encapsulator.
The proposed system was formulated using 3 wt%–6 wt% KCl as the base fluid, and CLAYSEAL? PLUS and CLAY SYNC II shale stabilizers for inhibition. The detailed formulation is shown at right.
Logistical arrangements were put in place to ensure that the system additives were available to support the well and future operations, if the HYDRO-GUARD application proved successful.
Economic Value Created
The well was drilled to total depth successfully within the projected time frame. No wellbore issues related to hole instability were experienced during the project.
The HYDRO-GUARD system provided excellent inhibition while drilling through the post-salt section and eliminated the environmental risks associated with OBMs. The projected savings include avoiding skip rentals, transportation, and disposal costs related to cuttings when the zero-discharge regulation is fully implemented. The cost per barrel of the HYDRO-GUARD system was lower than OBM options.
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