Characterization of clay scales forming in Philippine geothermal wells

Journal Article · Sat Dec 31 23:00:00 EST 1988 · Geothermics; (USA)

DOI:https://doi.org/10.1016/0375-6505(89)90067-9· OSTI ID:5385939

Reyes, A G ^[1]; Cardile, C M ^[2]

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1. Philippine National Oil Co., Geothermal Div., Fort Bonifacio, Metro Manila (PH)
2. Chemistry Div., Dept. of Scientific and Industrial Research, Private Bag, Petone (NZ)

Smectite scales occur in 24 out of the 36 blocked wells located in Tongonan, Palinpinon and Bacon-Manito. These comprise 2-85% of the well scales and form at depths of 33-2620 m, where measured and fluid inclusion temperatures are 40-320{sup 0}C. Most, however, occur below the production casing show where temperatures are {ge}230{sup 0}C, often at depths coinciding with aquifers. The clay scales are compositionally and structurally different from the bentonite used in drilling, which is essentially sodium-rich montmorillonite. The clay deposits are expanding, generally disordered, and combine the characteristics of a montmorillonite, saponite and vermiculite in terms of reaction to cationic exchange treatments, structure and composition. Six types of clay scales are identified, but the predominant one, comprising 60-100% of the clay deposits in a well, is Mg- and Fe-rich and referred to as a vermiculitic species. The crystallinity, degree of disorder, textures, optical characteristics, structure and relative amounts of structural Al, Mg and Fe vary with time, temperature and fluid composition, but not with depth and measured pressure. Despite its variance from bentonite characteristics, one of the dominant suggested mechanisms of clay scale formation uses the drilling mud in the well as a substrate, from which the Mg- and Fe-rich clay evolves.

• OSTI ID: 5385939
• Journal Information: Geothermics; (USA), Journal Name: Geothermics; (USA) Vol. 18:3; ISSN GTMCA; ISSN 0375-6505
• Country of Publication: United States
• Language: English

Related Subjects

15 GEOTHERMAL ENERGY
150200 -- Geology & Hydrology of Geothermal Systems
150903* -- Geothermal Engineering-- Corrosion
Scaling & Materials Development
152002 -- Geothermal Data & Theory-- Properties of Minerals & Rocks
ALKALINE EARTH METALS
ALUMINIUM
ALUMINIUM COMPOUNDS
ALUMINIUM SILICATES
ASIA
BENTONITE
CHEMICAL COMPOSITION
CLAYS
DEVELOPING COUNTRIES
ELEMENTS
ENERGY SYSTEMS
FLUIDS
GEOTHERMAL FLUIDS
GEOTHERMAL SYSTEMS
GEOTHERMAL WELLS
HYDROTHERMAL SYSTEMS
IRON
ISLANDS
MAGNESIUM
METALS
MINERALS
OXYGEN COMPOUNDS
PHILIPPINES
SCALING
SILICATE MINERALS
SILICATES
SILICON COMPOUNDS
SMECTITE
TRANSITION ELEMENTS
WELLS