Sodium sulfonated asphalt is a water soluble material made by a unique sulfonation process. It is a versatile, total mud conditioner that stabilizes shale formations, significantly increases lubricity, lowers high temperature high pressure fluid loss (HTHP) water loss and enhances filter cake properties in both oil and water-based drilling fluids. The product can be mixed in most water-based and all oil-based and synthetic muds. PROCESS
Sodium sulfonated asphalt is produced by reacting asphalt with SO3. The SO3 reacts with available double bonds. This creates chemically altered sulfonated material. It is then neutralized with sodium hydroxide.
asphalt + sulfonator --> sulfic acid asphalt,
sulfic acid asphalt + NaOH --> sodium sulfonated asphalt
This process gives a material that is highly anionic (has a negative charge). It is also partially soluble in water. Particle size ranges from very small to very large. This large variation in particle size range gives a high probability of having particles the correct size to plug holes in both rock and wall cake. The anionic character also gives it an affinity for broken rock and clay edges which are charged sites.
ADVANTAGES
Hard asphalt not helpful to reduce the high temperature and high pressure filter loss of drilling mud, and even will increase the high temperature and high pressure filter loss. Compared to that ,It has excellent filter loss control performance, especially the control of high temperature and high pressure (HTHP) filter loss. It is inhibitory to water-sensitive shale and drilling cuttings, and reduces its damage.
Sulphonated asphalt treated OBM gave much higher return permeability values (62% versus 27%) over the OBM sample containing conventional fluid loss additives. Also filter cake cleanup better with the SA – treated mud sample. It is shows sulphonated asphalt to oil base mud does not have a negative effect on the formation permeability,By lowering the fluid loss with asphalt under dynamic conditions, the fluid loss and filter cake integrity are greatly improved thereby reducing the invasion of solids into the formation.Also it reduces stick/slip by reducing excess wall cake as evidenced, and making the wall cake more compressible.
