Stable invert emulsion with oil wet solids is achieved using invert emulsifiers and wetting agents. This paper reviews the chemistry and performance criteria of traditional invert emulsifiers and wetting agents utilized in formulating stable invert emulsion drilling fluids. However, occasionally such stable invert emulsion drilling fluids can be destabilized due to various hostile conditions encountered during drilling operation, and can adversely impact the drilling cost. Extreme preventive measures cannot avoid such hostile conditions such as sudden water influx, excessive solids and salt contaminations during drilling. Upon solids becoming extremely water wet with "flipped emulsion", it becomes impossible to fix the drilling fluid, resulting in expensive maneuver. Often situation cannot be corrected with traditional wetting agents and emulsifiers even at high level of treatments. New innovative chemistry addresses the severe water-wetting and emulsion instability of invert emulsion under extreme challenging and hostile situations. The unique water soluble oil mud conditioner (OMC) synergistically enhances the performances of traditional oil-wetting agents and emulsifiers at very low, as little as 0.5 ppb levels of treatment. This OMC improves and extends the efficacy of the traditional invert emulsifiers and oil wetting agents resulting in reduced usage of these additives with excellent economic advantages. The 15.0 ppg, invert emulsion drilling fluids were prepared using 2-3 ppb of primary and secondary emulsifiers, and these fluids were destabilized using high shear mixer for 7-8 hours. The destabilized fluids had severe water wet solids and ES value of less than 5. These destabilized fluids, upon treating with 0.5 ppb of newly developed OMC instantly became oil-wet and shiny and ES was increased to greater than 500. To demonstrate the effectiveness of OMC in pre-treatment situation, the base fluids treated with 0.5 −1.0 ppb of OMC showed superior mud stability compared to base fluid when contaminated with sea water, fine solids, barite and high salt contaminations. The OMC is flexible in its application and can be used as pre-treatment to improve the overall performance of drilling fluids and can also be used for post-treatment to recover the drilling fluids, which have been rendered unusable.

Exploration and Production Operators prefer a non-damaging non-aqueous fluid (NAF) for drilling Reservoir. One of the requirements of non-damaging system is a clay free system and it should perform as good as any NAF Fluid. For drilling in deep water environment, it is necessary to have flat rheology of NAF over a wide range of temperatures. An innovative polymeric rheology modifier was used to develop Clay Free Invert Drilling Fluid (CFIDF) which provides dual function to achieve a clay free system as well as flat rheology when measured over a wide range of temperatures from 40 to 150 °F. The flat rheology is required in offshore deep water drilling due to varying temperature profile from 4 °C at the bottom of sea to as high as 100 °C or even higher at bottom of hole. Lower temperatures increase the rheology leading to higher ECD and at higher temperatures the rheology is lowered leading to hole cleaning issues. Flat rheology profile minimizes or eliminates such adverse effects on ECD or hole cleaning activity. The newly developed clay free system utilizes a single rheology modifier component to provide dual functions of providing true clay free system and offers flat rheological profile without sacrificing the vital mud parameters such as emulsion stability, fluid loss control and rheology. In addition, the system uses a new rheology modifier that provides a temperature-independent rheology profile for hole cleaning, barite suspension, ECD management. The system can be formulated for deep-water applications with mud weights up to 18.0 lb/gal and bottom hole temperatures up to 350°F. Recent successful field trials as a clay free system for drilling reservoir indicated that the new system is easy to maintain and provides good fluid performance in terms of drilling rate, ECD management, lost circulation control and hole cleaning. The product provides an excellent rheological profile and was used in the field at a low dosage of 1 ppb. Even at this low dosage LSRV was above 10 in 8 ½″ Hole with yield point of greater than 15 lbs/100 sq.ft. When the system was contaminated with a severe saltwater flow, there were no fluid-related problems before the synthetic/water ratio was restored. The new fluid system exhibits flat rheology profiles and non-progressive gel structures. The system showed excellent hole cleaning with excellent thixotropic properties. This resulted in a noticeable reduction of lost circulation potential in lost circulation prone areas due to manageable ECD. An innovative rheology modifier which provides clay free system and offering flat rheology profile has been developed and successfully used in field. The rheology modifier can minimize or totally eliminate the organophilic clay to improve the quality of non-damaging reservoir drilling fluid.

Exploration and Production operators prefer non-damaging non-aqueous fluid (NAF) for drill-in reservoirs. One of the requirements of non-damaging system is clay free system and it should perform as good as any conventional NAF. For deep water drilling, it is necessary to have flat rheology of NAF over a wide range of temperatures. An innovative rheology modifier which provides clay free system and also offers flat rheology profile has been developed and successfully used in field. The rheology modifier can minimize or totally eliminate the need of organophilic clay to improve the quality of non-damaging reservoir drilling fluid. The paper will discuss the chemistry of newly developed polyamide resin-based rheology modifier and compare it with other poly-amide resin chemistry currently used in industry. Also, the critical parameters which are required to synthesize cross-linked polyamide resin that provide thixotropic properties to NAF will also be discussed The newly developed clay free system utilizes a single rheology modifier component to provide dual functions of providing true clay free system and offers flat rheological profile over wide range of temperatures. The dual function is achieved without sacrificing the vital mud parameters, such as emulsion stability, fluid loss control and rheology. In fact, these mud parameters are enhanced due to surfactant characteristic incorporated in newly developed poly-amide resin-based rheology modifier. The clay free system can be formulated for deep-water applications with mud weights up to 18.0 lb/gal and temperatures up to 350°F. Recent successful field trials as a clay free system for drilling reservoir indicated that the new system is easy to maintain and provides good fluid performance in terms of drilling rate, ECD management, and hole cleaning. This product provides an excellent rheological profile at a low dosage of 1 ppb. Even at this low dosage, LSRV was above 10 in 8 ½" Hole with yield point of greater than 15 lbs/100 ft2. When the system was contaminated with a severe saltwater flow, there were no fluid-related problems before the synthetic oil/water ratio was restored.

A number of problems such as emulsion instability, environmental issues and cost, persist in current liquid invert emulsifier technology of non-aqueous drilling fluids (NADF). These short comings are mainly due to incorporation of required components, solvents and mutual solvents in formulating emulsifier package, however they can be mitigated through innovative powdered emulsifier technology. This paper will present concept, design and chemistry of novel powdered emulsifier technology and compare their performance against current liquid emulsifiers. New technology will include the development of solvent and mutual solvent free "solid state emulsifiers", and their applications in mitigating or eliminating the adverse effects of mutual solvents and other solvents which are incorporated in traditional liquid emulsifier technology. New technology in the form of advances made in emulsion technology, unique manufacturing technology of emulsifier additives and fluid formulations will be discussed. NADFs have been used since their early introduction in late 1930s1, primarily because of their performance benefits when compared to water-based drilling fluids. Despite the performance advantages, NADF technology has not been without challenges because the complexity of drilling operations has grown enormously. These new challenges have required that NADFs be environmentally friendly, stable and possess desirable mud properties over broad range of temperatures and pressures, effective in broad range of applications and be cost effective. Through the constant efforts of research scientists in drilling fluid industry, advances have been made in NADF formulations, particularly in base fluids and surfactant technology to overcome or mitigate these challenges 2. However, the problems still exist. Various test we conducted for performance comparison of conventional liquid emulsifier and new technology solid state emulsifiers. After analysing the results, it was concluded that mutual solvents used in formulating liquid emulsifiers resulted in reduction of emulsion stability as much as 30%. The laboratory assessment, comparison and field applications of the newly developed powdered emulsifier technology will be highlighted. The development of this innovative powdered emulsifier technology has mitigated or resolved many issues, such as pour point, toxicity and other logistic problems to keep the NADFs at the forefront of the drilling fluid industry. The paper will present newly developed concept and design of novel solid emulsifier technology to combat the associated challenges. These challenges include environmental issues, performance requirements, logistics and cost associated with current technology.