Innovative Use of Sea Water in Drilling Fluid Development
This work focuses on leveraging sea water as an alternative to inorganic salts in drilling fluid formulations, reducing logistical costs and enhancing offshore operations. The development process involved scaling down additives to nano-size, aiming to create a product that not only replaces Lime in mud composition but also enhances fluid loss control and emulsion strength. By strategically including inorganic and water-soluble components, the product ensures minimal damage to rock permeability, offering a cost-effective and sustainable solution for the oil and gas industry.
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New additive creates additional value for drilling fluid Non-aqueous mud formulations use aqueous solution of various inorganic salts as internal brine phase. The present work focuses on using sea water as an alternative to these salts and thus facilitate the use of naturally available seemingly never-ending resource in off-shore environment. This concept has expanded the horizon of drilling fluid role by eliminating all logistic and transportation cost of shifting brine from shore as well as created additional storage facility for various fluids as there is no need to block and storage place for sea water. The foundation of this work was laid thoughtfully after carefully understanding the role of each component of mud and the chemistry as well as its mechanism of their action to explore the inclusion of sea water without compromising with any of the features of non-aqueous mud and thus not only make off-shore operations less dependent on shore base, but also offer huge cost saving on logistic, transportation ,cost of mud with the added advantage of reduced HSE incidents, often associated with the use of Calcium Chloride solution, most commonly used inorganic salt as internal brine phase
New additive creates additional value for drilling fluid The product development started with the concept of scaling down a part of the newly short-listed additive to Nano-size and thereby increase its effectiveness many folds. This provides leverage to reduce the dose of new additive and thus create room for blending other essential compounds to provide a chemical environment conducive to use of sea water. The newly developed product was aimed first to replace Lime from non-aqueous mud composition, which acts as an activator to emulsifier. The replacement of Lime was finalized after exhaustive testing in lab with all types of formulation to ensure its complete compatibility as well as ability to function with equal effectiveness in all ranges of mud formulations. In order to match the alkalinity level of Lime in new product, another high alkalinity additive was also included in the blend to provide the same level of activation to emulsifier as provided by Lime. To provide the same type of ionic atmosphere as calcium Chloride solution. This required enormous testing on various formulations and the target activity level was +/- 0.87 The number was chosen on the basis of the activity of rock matrix at shallow depth in off- shore environment while ensuring that hole-stability was not compromised.
New additive creates additional value for drilling fluid The focus of using sea water and not compromising with any feature of mud was always in fore- front during all these experiments to ensure that there is no drift from the objective. It was purposely planned to include only inorganic and water soluble components as various component of the final product, as the important role of not damaging the rock and help retain its native permeability as much as possible, was always emphasized. With the advent of product development few pleasant surprises further increased the utility of the product and ability of providing Fluid loss control to a reasonable extent without adding any fluid loss control additive is one important factor worth sharing as it directly further reduces the per barrel cost of formulation! The feature of fluid loss control got imbibed in the product by virtue of increased surface area as a result of pulverizing one of the component of the product to sub-micron size. In addition to it, the product also offers better emulsion strength when compared to Lime. With the presence of varied sized particles it was natural to expect that the product would further aid in formulation of effective filter cake around wall of open hole. However, this feature will accrue to the extent that the product is also able to mimic the role of Non-invasive fluid was not thought of. Here also the product surpassed expectations by acting as a NIF in its own individual capacity, thereby minimizing dependence on sized calcium carbonate and / or Graphite to resist down-hole dynamic losses.
New additive creates additional value for drilling fluid In terms of chemical composition the product is best described as a blend of alkali and alkaline earth metal compounds in a specific ratio with sizes ranging widely to provide adequate filtrate invasion and ratios facilitating complete activation of emulsifier as well as imparting the feature of increased activity level to allow use of sea water as internal brine phase. Being inorganic in nature the product does not suffer from the limitation of degradation at higher temperature and has a long shelf life with no specialized requirement for storage. When compared with Lime and calcium Chloride, the product is intrinsically safer to handle. By virtue of its inorganic origin and miscibility with water, the product does not require and specialized shearing / mixing and extra time to yield to its optimum capacity. The best feature of the product is its complete compatibility with all the products used in mud preparation. Whenever strict fluid loss control is required, all we need is addition of fluid loss control agent in the same circulating mud at a dose reasonably lower than normally added, as part of the fluid loss control is already provided by the product. Changing over to a mud of different parameters for different phases is just a matter of treating the same mud to tweak the parameters, a feature much desired when compared to changing the entire system.
New additive creates additional value for drilling fluid Initial evidences indicate that the product does not cause any damage to the rock by virtue of its presence in the formulation as a substitute to Lime. This feature offers excellent advantage to the system formulated with this product as the same mud can be used as reservoir drill-in fluid also! Due to increased number of particles in mud with addition of new product the gelation feature of the mud can sometimes cause undesirable trait in mud formulation . In order to not to let that happen to the extent that it can be a bottle-neck to the performance of the mud, the ratio of various components has been carefully crafted and strictly adhered to, as a result of which, the product is capable of further increasing its utility in terms of an even stricter fluid loss control and thus reducing the addition of fluid loss control agent . The product helps in completely eliminating all contamination related issues arising out of use of calcium chloride brine, which is transferred from supply boat to rig by various lines that can accidentally contaminate each other. Contamination of brine with other fluids stored on rig is also eliminated as sea water does not requires to be separately stored in dedicated rig pits, thus more pit space is freed up on rig to facilitate sore higher volume of other fluids.
VARIOUS ADVANTAGES OFFERED BY THE PRODUCT The single biggest advantage is elimination of Calcium Chloride brine from non-aqueous mud formulation and replacing it with Sea Water. This drastically reduces the dependence on shore for mixing non-aqueous mud and completely eliminates all transport / logistics related issue arising out of shifting of Calcium Chloride. The contamination of two different chemicals/commodities with Calcium Chloride is now non-existent. The mud mixing process on rig becomes less cumbersome and faster. It makes non-aqueous mud preparation a more safe process and eliminates all hazards related to use of Calcium Chloride brine. Since the product frees us from use of Calcium Chloride brine and Lime, the per barrel cost of Non-aqueous mud is reduced by almost 10 % only in the formulation leave aside the cost saving of the entire drilling campaign by simplifying transportation and logistics related cost over-heads. It frees up pit storage space on rig by reducing the need of storing Calcium Chloride brine for drilling purposes. It speeds up Non-aqueous mud formulation by reducing the total number of additives to be used and thus saves rig time by facilitating quicker mixing of Non-aqueous mud, which is an direct saving in drilling campaign as this available time can be constructively utilized for other concurrent operations.
VARIOUS ADVANTAGES OFFERED BY THE PRODUCT Everything else remaining equals the new relaxed filtrate formulation can improve ROP. However this needs to be carefully monitored to ensure that relaxed filtrate does not induce any well-bore instability related issue. Since major component of the product is a waste bye-product from other industries which are available at a throw-away price and HTHP F/L as well as Calcium Chloride brine is not required any more for formulating non-aqueous mud with the new product, the overall per barrel cost of the Non-aqueous mud is considerably reduced and also it adds value to system by improving the overall efficiency. It converts the waste of one industry as a useful commodity for oil industry. The cost of bringing the product to a useful commodity is very low, which means there is no big capital investment. The only cost involved is in air jet milling the Knamp16 to sub-micron size. The technology is simple and it neither needs highly qualified staff nor any speciality equipment on board to run the system. It has no adverse effect on any of the other components of mud or the entire drilling process making it completely compatible to use
VARIOUS ADVANTAGES OFFERED BY THE PRODUCT The product is safe to handle and easily miscible in mud without requiring any specialized mixing system/process. The raw material being a bye-product of another industry - is available in abundance throughout the globe. The product does not require any specialized storage facility. By facilitating use of Sea water, the new product provides flexibility in rescheduling the sequence of operations to be carried out to focus on other time consuming jobs which can otherwise become bottle-neck to resume further drilling after installing BOP and running riser on deep water locations. Being inert to most of the storage conditions as well as chemicals it has a long shelf life. Regular use of the additive can free up the acetylene industry manufacturers from the burden of disposing /storing the waste and save on their working expenses. Another equally important fact is that use of sea water ensures that the component to mix Non-aqueous mud will never be in short-supply at any time, which cannot be the case with Calcium Chloride brine. The use of new product does not put any limitation on any of the products being currently used and also provides the comfort of adjusting the properties of non-aqueous mud with same additives, if required during any stage of operation .In short, there is no need to replace/change the entire mud, should there be a need to drastically change properties of mud for operational reasons.
