Relationship between reservoir mineralogy and optimum sandstone acid treatment

E. P. da Motta, Benjamin Plavnik, R. S. Schechter, A. D. Hill

Research output: Contribution to conferencePaper

2 Citations (Scopus)

Abstract

Mud acid treatments are normally designed by approximating the complex mineralogy of a sandstone using a 'lumping' procedure. Minerals are classified as either fast reacting or slow reacting and the rates of their reaction with hydrofluoric acid are determined by analyzing the acid effluent from acidized core plugs. For most treatments carried out at modest temperatures and at reasonable rates, this approach is satisfactory. In this paper, we show that at higher reaction temperatures, the simple two-mineral dissolution model does not apply because an intermediate product of the HF reaction with quartz, feldspars, and clays (H2SiF6) begins to react further with both clays and feldspars. This new reaction must be included to model the data. The additional reaction, not observed at lower temperatures, has important consequences when it does occur. For example, the acid injection rate is no longer a critical factor. In fact, slow rates in deep formations are preferred. The analysis presented here shows that retarded acids are unnecessary. Contrary to previous concepts, mud acid itself provides a deep penetrating capability. This surprising result may account for the high percentage of successful treatments even when carried out under a wide range of differing conditions.

Original languageEnglish
Pages323-336
Number of pages14
Publication statusPublished - 1 Jan 1992
EventProceedings of the International Symposium on Formation Damage Control - Lafayette, LA, USA
Duration: 26 Feb 199227 Feb 1992

Other

OtherProceedings of the International Symposium on Formation Damage Control
CityLafayette, LA, USA
Period26/2/9227/2/92

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ASJC Scopus subject areas

  • Engineering(all)

Cite this

da Motta, E. P., Plavnik, B., Schechter, R. S., & Hill, A. D. (1992). Relationship between reservoir mineralogy and optimum sandstone acid treatment. 323-336. Paper presented at Proceedings of the International Symposium on Formation Damage Control, Lafayette, LA, USA, .