630 imbt. CARBONATE POROSITY PROBLEMS [Ch. 33 



mental research regarding the nature and origin of carbonate porosity. 

 Chemical composition and relationship to other geologic phenomena 

 should include both common and uncommon characteristics of car- 

 bonate waters, with special emphasis on the measurements of sodium 

 and potassium, also organic acids, if present. 



PHYSICAL PROPERTIES OF CARBONATE SURFACES WITH SPECIAL 

 EMPHASIS ON WETTABILITY 



The recovery of the maximum amount of oil from a carbonate reser- 

 voir depends on a large number of factors, among which conditions of 

 porosity and permeability are important considerations. Of impor- 

 tance also are the physical and chemical make-up of the reservoir 

 rock and the fluid retention characteristics of the reservoir material. 

 The suggested study should consider the "wetting" effect of various 

 reservoir fluids, both oil and water, and also free gas in solution. 

 Equally important in such a study would be experimentation in the 

 reduction of surface tension by introduced chemicals or changes in the 

 physical characteristics of the reservoir rock. 



LABORATORY RESEARCH APPLIED TO FIELD PROBLEMS 



The ideal coordination of carbonate research would be the applica- 

 tion of the suggested procedures to the same reservoir material from 

 a producing field exhibiting as many variables as possible. Thus a 

 more or less complete picture could be formulated from various re- 

 search approaches. Conditions of carbonate deposition and porosity 

 formation vary widely over short distances even in the same forma- 

 tion. Data that cannot be correlated are of little value to the cor- 

 rect solution of a complicated problem. 



A well-organized program of carbonate research should investigate 

 the formation and development of porosity in the recently deposited 

 limestones as a pattern to be extended to the older rocks which have 

 suffered many postdepositional changes. Through a better under- 

 standing of the early characteristics of carbonates, we should find our- 

 selves in a better position to unravel the complicated history of the 

 older carbonates. 



These research approaches are suggested as methods to be used to 

 correlate chemical and physical characteristics of carbonates to the 

 development of porosity and permeability patterns. From such in- 

 vestigations, it should be possible to predict with reasonable certainty 



