NEW DRILLING FLUID TECHNOLOGY 钻井液体系新进展

Principles of Drilling Fluids 钻井液工艺原理 Chapter10 NEW DRILLING FLUID TECHNOLOGY 钻井液体系新进展 Prof. Dr. XiuhuaZheng E-mail: Xiuhuazh@cugb.edu.cn Exploration Dept. School of Engineering and Technology, China University of Geosciences(Beijing) 中国地质大学(北京)工程技术学院勘查教研室

硅氧四面体 • 八面体晶片方钻杆 • 单元晶层 • 氢键 • 晶层间距 • 晶格取代 • 吸附阳离子 • 可交换阳离子 • 蒙脱石 • 高岭石 Test for §9 • Silica-Oxygen tetrahedron • octahedral sheet • 2:1-Type unit layer • hydrogen bonding • c-spacing • Isomorphous substitutions • Adsorption of a cation • exchangeable cations • Montmorillonite • Kaolinite

硅酸盐 正电胶聚合醇微泡甲酸盐钻井液无侵害钻井液聚胺钻井液 Glossary of §10 Silicate-based Mixed Metal Hydroxide Polyol Micro-bubble Formate Non-invasive Polymeric Amine Cloud point"（浊点）

Contents 1 Silicate-based Drilling Fluid（硅酸盐钻井液） 2 Mixed Metal Hydroxide Drilling fluid（正电胶钻井液） 3Polyol Technology System（聚合醇钻井液） 4 Micro-bubble Drilling Fluid（微泡钻井液） 5Formate Drilling Fluid（甲酸盐钻井液） 6 Non-invasive Drilling Fluid（无侵害钻井液） 7 Polymeric Amine Drill Fluid（聚胺钻井液）

1.Silicate-based Drilling Fluid • Introduction • silicate-based drilling fluids using sodium and potassium silicate（硅酸钠或硅酸钾）is a lower cost and effective drilling fluid with very good shale inhibitive capacity, reduced formation damage and environmental safety. • silicate-based drilling fluids offers the flexibility and versatility to design a mud system for almost any drilling environment and provides.

Molar of silicate is the weight ratio of SiO2:Na2O (重量比）, being the key parameter that determines the properties of drilling fluid. liquid silicates with higher ratios will contain proportionately greater levels of condensed, complex species with higher molecular weights. the low and mid ratio liquids will contain significant levels of low molecular weightchains andcyclics as well as free mono-silicate. • Characteristics

Mechanism In-gauge holes are achieved through a unique combination of versatile chemical reactions; most notablygelation(胶凝) and/or precipitation（沉淀）on shale surfaces. These reactions also lead to the sealing of micro-fracture, cracks and rubble giving a silicate drilling fluid a decided advantage over any oil mud, significantly reducing potential mud losses and costs. silicate drilling fluids provide a thin, tough, ultra low permeable filter cake reducing drilling problems such as differential sticking or torque & drag, while providing improved cementing.

Advantages Superior Well Bore Stability ExcellentShale Inhibitive Capacity ExcellentROP Runnability Safety Cost Environment

2.Mixed Metal Hydroxide Drilling Fluid (MMH)正电胶钻井液 Mixed metal layered hydroxide compounds are inorganic materials which are made up of discreet layers, consisting of two or more metal ions surrounded by hydroxide ions. • Characteristics

When added to pre-hydrated bentonite, the positively charged MMH particles interact with the negatively charged clays forming a strong complex that behaves like an elastic solid when at rest. • Characteristics

the sheets are electron deficient and a crystallographic positive charge is generated, The surface interacts with these anions through an ion exchange mechanism, similar to that of anion exchange resin or clay mineral. • Mechanism

Advantages MMH has unusual rheology: excellent hole-cleaning properties MMH has great gel strength at rest, the structure is easily broken. MMH also provides chemical shale inhibition. MMH is a special fluid sensitive to many traditional mud additives and some drilling contaminants.

Application horizontal and short-radius wells unconsolidated or depleted sandstone high-temperature, unstable shale wells with severe lost circulation

3.Polymerized-Alcohols Drilling Fluids聚合醇钻井液 • Characteristics Polyol is the generic name for a wide class of chemicals including glycerol(丙三醇),polyglycerol(聚丙三醇),glycols（乙二醇）and propylene glycol（丙二醇). The water solubility of glycol decreases as temperature increases. The temperature at which glycol and water separate is known as the "cloud point"（浊点） Polyol drilling fluid has the capability of excellent borehole stability, upgraded lubrication on the mud itself and the borehole wall, reduced formation damage and lowered dilution rate.

· the entire solution temperature has risen above the cloud point, two distinct phases become visible. When the solution cools, the glycol and water recombine to form a clear, single phase.The glycol drops out of solution and attaches to the “hot” shale. This protective layer prevents the shale from interacting with the water, minimizing swelling. • Mechanism

Advantages The high performances of the glycol system are: • superior lubricity • improved fluid hydraulics • ease-of-conversion • excellent borehole stability • enhanced shale inhibition.

4. Micro-bubble (Aphron) Drilling Fluid可循环微泡沫钻井液 The Structure ofa gas aphron at the molecular level: The aphron is composed of a gas core and a more complex soapy shell, which has an inner as well as an outer surface with a sheath of viscous water between them. Structure of a gas aphron • Features

·Energized Micro-Environment of Aphron Structure and Bubble Flow An aphron, which has a diameter of 96 microns at the 0.1 MPa surface pressures, is compressed into a smaller one with 16 micron diameter at 21.89 MPa. • Features

Bridging Mechanism in a Loss Zone pressure resists intrusion of hydrophobic micro-bubbles into capillary restrictions in the formation. • Features

Aphron drilling fluid possesses unique viscosity structure and viscosity size, forms a temporary blocking zone that deters or delays the drilling fluid to enter reservoir, and enjoys better leakage-proof and reservoir-protection. • Mechanism

5. Formate Drilling Fluid 甲酸盐钻井液 • Characteristics Formate is safe for the environment and crew. Recycling cuts fluid costs by reclaiming formate and using them in multiple wells. No weighting agent means no sag, and no sag means the elimination of a whole pile of problems, from additional hours circulating and conditioning muds to serious well control incidents.

Naturally weighted.Formate brine drilling fluids are naturally weighted, monovalent fluids with a maximum density of 2.30g/cm3 (19.10 ppg) for cesium formate, 1.57 g/cm3 (13.05 ppg) for potassium formate and 1.30 g/cm3 (10.85 ppg) for sodium formate. • characteristics

characteristics An adequate amount of viscosifier, FL control agent, lubricant and defoamer are concurrently used in the fluid for obtaining a system with satisfactory properties. This system is characterized by its excellent stabilizing capacity and evidently reduced formation damage. High cost and enormous quantity of formate required limit the application range of this system.

Advantages No weighting materials means no sag, improved ECD (Equivalent Circulating Densities) and better overall circulation rates High compatibility with reservoir fluids and minerals maximizes reservoir protection and improves well productivity Extremely versatile fluids used in all phases of drilling and completion eliminate the costs of fluid change Optimized hydraulic flow maximizes power transmission, facilitates hole cleaning and increases ROP (Rate of Penetration)

Advantages Alkaline properties give outstanding corrosion protection Stabilizes shale and enhances borehole stability Improves well control and allows faster tripping Excellent compatibility with elaptomers and polymers Facilitates faster and more accurate logging – even with extended reach drilling Best environmental and safety profile of all drilling and completion fluids

6. Non-invasive Drilling Fluid（无侵害钻井液） • Introduction Conventional drilling is conducted with an over-balanced pressure on the reservoir formation, which causes the drilling fluid to invade and damage the rock. In order to overcome the problem of formation while drilling, a method was developed to drill with a bottom-hole pressure below the pore pressure, called Under-balanced Drilling-UBD. The development and recent increase in UBD activity is due to the understanding that there will be no formation damage if a reservoir is drilled under-balanced. UBD is, most probably, still the best way to achieve no-damage drillingSM. However, the big problem associated with UBD is how to guarantee that no overbalance periods will happen while drilling or completing the well. Also, there are many situations in which technically it is not possible to have an under-balanced pressure kept at all times. Just a small period of overbalance may cause damaging filtrate invasion.

characteristics The NIFSM is a new class of drilling fluid, with ultra-low solids content, less than 10 ppb. The characteristics of this fluid are its capacity to build up a sealing membrane of certain strength into certain thickness of the formations around the borehole by addition of special polymer type additives into a water base or oil base drilling fluid.

Advantages Totally friendly to the environment Effective sealing of hetergenneous permeable formation with the same fluid composition Allows increase of the leak-off pressure Widens a narrow mud weight window Seals permeable formation and micro-crack in shale Can drill the overburden and the reservoir with the same fluid, including completion Reduced transport and storage costs Reductionof differential stuck pipe risk Reductionof fluid losses, virtually eliminating them Reduction of well-bore instability problems Reduction formation damage

Formulation • DWC2000, a viscosifier; (max dosage 30 kg/m3) • FLC2000, a dynamic fluid loss reducer (routine dosage 6~12 kg/m3); • KFA2000(dosage range 20~300 kg/m3), a lubricant The three additives are of one-sack type and can be used individually or in combination and the formulation must be determined by pilot tests.

When added to a water-based fluid, some of the polymers in the blend dissolve to provide fluid loss control similar to many conventional additives. However, other species only partially solvate because of their oil-loving characteristics; these polymers organize into deformable aggregates or micelles. • Mechanism

these micelles have the ability to form rapidly a low permeability seal over pore throats and micro-fracture, thereby greatly limiting fluid invasion. • Mechanism

In some respects, the micelles act like the water droplets in invert emulsion oil mud; these water droplets are known to concentrate in the filter cake where they make a major contribution to the invasion control seen with oil mud. • Mechanism

By functioning as a very low permeability barrier, the additive has the ability to protect weak formations against pressure transmission and fracturing. This effective increase in fracture gradient widens the safe drilling window and has great potential for improving drilling performance, not only in micro-fractured formations but also in depleted zones, unconsolidated sands, etc. • Mechanism

Particle size analysis suggests that the micelles range from a few microns to close to 1000 microns in diameter (the d50 is around 60 microns, the d10 is 9 microns and the d90 340 microns). • Mechanism

Comparison with traditional drilling fluids Particles are calcium carbonate and salt, an acidification job or dissolution with water would eventually remove the damage created. Bridging approach requires the particles to penetrate into the rock, and find a suitable pore size, according to the particle size distribution. Maintenance of the NIFSM is extremely easy. Addition of the fluid loss controller additive, FLC2000, is enough to maintain the sealing effectively. And the amount required is dictated by a test conducted against a sand bed. If the sealing is not effective, addition of more FLC2000, is needed.

Application Reservoir inter-bedded with shale Reservoir with different pressure exposed in the same open hole section Severe well-bore instability problems due to mechanical causes ( high tectonic stresses, for example) Narrow mud weight window

7. Polymeric Amine Drill Fluid (聚胺钻井液) • Introduction A high performance water-based mud (HPWMB-also called amine base drilling fluid) containing clay and shale stabilizers, a ROP enhancer, and sealing agents was developed to drill the well and is taken as the substitution for oil base mud. The high performance drilling fluids use a new cationic polymer—ether/glycol polyamine as shale inhibitor。This amine salt has a high inhibitive and bit balling prevention capacity, and is environmentally friendly.

Evolution of nitrogen-based shale inhibitor Ammonium Chloride → Ammonium Salt mud Systems → Organic Cationic Materials → Quaternary Cationic Polymers → (PHPA-Partially Hydrolyzed Polyacrylamide) → Quaternary Alkyl-Amine →Quaternary Hydroxyl Amines) → Amphoteric Poly-amine Acids →Alkyl-Diamines→ Polyamine Glycols → Ether/Glycol Polyamines.

HPWBM drilling fluid system significantly reduces clay dispersion, hydration, and accretion outperforming previously developed inhibitive WBM systems and reaching into the performance territory of OBM. • characterictis

The CHS functions in mechanism similar to potassium chloiride in suppressing clay hydration, without being constrained by the performance and environmental issues associated with KCl. • mechanism

The data presented demonstrate how the CHS effectively reduces the hydration and dispersion of reconstituted shale wafers in laboratory tests. • mechanism

advantage shale stability through reduced or reversed pressure transmission effects suppression of reactive swelling clays improved cuttings encapsulation and solid removal efficiency minimizing differential sticking tendencies maximizing rate of penetration(ROP) minimizing torque and drag environmental compliance

Future development Extension of amine and oligomer performance to higher temperatures Economically tailor oligomer to optimum and consistent molecular weight and configuration for improved filtration control and membrane development. Source less expensive amines which meet performance expectations. Investigate of a broad range of organic and inorganic osmotic drivers which complement membrane development.

Discussion • Why and how are the new drilling fluids developed, and their applications.

NEW DRILLING FLUID TECHNOLOGY 钻井液体系新进展