Summary Laboratory and field results show that the Capillary Suction Time (CST) filtration device can be used to characterize the colloidal nature of shale particles, to determine optimal salinity for inhibition, and to analyze drilling-fluid filtrate effect on cuttings dispersion at the wellsite. The concept of potential energy developed between particles is advanced to improve the understanding of borehole stability. Introduction Selection of a drilling fluid to minimize hole problems and to maintain mud stability is a complex problem that requires technical expertise. Generally, drilling operators make mud selections and find solutions to problems on the basis of previous experience in a geologic area. Shale formations are the primary culprits responsible for wellbore and mud stability problems. The time-dependent change and in the filtration and rheological properties of a slurry provides a clue to the nature of a properties of a slurry provides a clue to the nature of a formation problem. The field-adaptable CST filtration device can be used to predict clay behavior and to improve mud selection by measuring the hydrating and dispersion properties of shales. properties of shales. Clays, the active components of shales, have dispersive characteristics that are unique among all other minerals. The silicate matrix of clays develops bond strength between particles from various cations, pressure, temperature, and water present during deposition. Shear and chemical forces present during drilling act on the aggregrated clay bond, causing dispersion of the shales. The dispersive forces acting on the shale can be classified as mechanical and chemical. Mechanical dispersion results from drag forces related to fluid flow and from particles that collide with the rotating pipe, bit, and each other. Chemical dispersion, which causes clay swelling, results from repulsive and attractive forces between the clay and various polar and ionic materials present in the drilling fluid. Aggregation/Dispersion Aggregation/dispersion of drilling muds has been used to describe the size, concentration, and net interaction of particles in a system. Aggregation occurs when particle particles in a system. Aggregation occurs when particle attraction is high and fluid particle interaction is weak, resulting in high gel strengths and filtration rates. Dispersion, or deflocculation, on the other hand, occurs when particle attraction is weak and fluid particle interaction particle attraction is weak and fluid particle interaction is high, resulting in lower gel strengths and filtration rates. Dispersion in fresh water can be compared with deflocculation of clays in salt solutions. Deflocculation is process of breaking down larger aggregates into smaller process of breaking down larger aggregates into smaller aggregates and forming good fluid-particle interaction. Because the CST value reflects the state of aggregation/dispersion of shale slurries, it is necessary to review the fundamental concepts governing aggregation/ dispersion between particles.

Compd. 7-Benzylidenebutyryl peroxide r(p-Ch1orobenzylidene)butyric acid 7-(p-Chlorobenzy1idene)butyryl peroxide a-(p-Fluoropheny1)allyl alcohol p-Fluorocinnamyl bromide y-(p-F1uorobenzylidene)butyric acid 7-( pFluorobenzy1idene)butyryl peroxide y-(p-Methylbenzy1idene)butyric acid 7-(p-MethyIbenzy1idene)butyryl peroxide 7-( p-Methoxybenzy1idene)butyric acid 6-(pMethoxyphenyl)valeryl peroxide Wave length region, w 0.0-3.0 5.5-6.0 6.0-7.0 8.0-10.0 5.55-5.64 (s) 9.38 (s)6.82 (s) 6.67 (s) (doublet) 5.50-5.60 (9) 6.70 (5) 9.13-9.40 (s) (doublet) (doublet) 2.30 (m) 6.22 (s) 8.13 (s) 3.40 (s) 6.62 (s) 8.63 (s) 6.22 (s) 8.11 (s) 6.62 (s) 8.31 (s) 8.61 (s) 5.61 (s) 6.20 (m) 8 . 1 0 (s) 6.60 (s) 8.60 (s) 5.5-5.59 (s) 6.22 (m) 8.21 ( 8 ) (doublet) 6.62 (9) 8.62 (m) 5.86 (s) 7.10 (m) 5.51-5.61 (s) 9.43 (m) 5.98 (s) 6.28 (m) 8.07 (s) 5.54-5.61 (s) 6.64 (s) 8.04 (s) (doublet) (donblet) 6.22 (m) 8.56 (m) 6.86 (m) 9.67 (m)acid separated as a white, creamy solid. It was extracted into ether; the latter was washed with water and dried over magnesium sulfate, and the ether was removed. The resulting solid was recrystallized from toluene. The over-all yield of y -( p methoxybenzylidene)butyric acid from the ethyl ester of the keto acid was 67%. Some chemical and physical properties of this acid are listed in Table VI; its infrared spectrum is described in Table VII.

Methyl radicals are formed in solution by photolysis of methylmercuric iodide with light of wavelength 3130 A. Several aromatic solvents have

Several aromatic solvents have been alkylated using the photolysis of methyl-, ethyl-, and n-butyl-mercuric iodide as the sources of alkyl radicals. The relative proportions of nuclear and side-chain attack on toluene and on isopropylbenzene, and the distribution of the isomeric products of nuclear alkylation of toluene and of chlorobenzene are in agreement with the postulate that alkyl radicals are more nucleophilic than aryl radicals. The mechanism of formation of a-methylstyrene, as well as bicumyl, by side-chain attack on cumene is discussed.

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