Influence of Clays on the Production of Hydrocarbons

Abstract

This paper was prepared for the Society of Petroleum Engineers of AIME Symposium on Formation Damage Control, to be held in New Orleans, La., Feb. 7–8, 1974. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon requested to the Editor of the appropriate journal, provided agreement to give proper credit is made. provided agreement to give proper credit is made. Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussion may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines. Abstract Many hydrocarbon producing formations contain clays that can influence primary production as well as stimulation primary production as well as stimulation results. The clays that have frequently been found in these horizons are montmorillonite, mixed layer, illite, kaolinite and chlorite. A correlation has been developed that indicates the types of clays that may be expected in certain areas and depth of burial in the Gulf Coast region. All of the above noted clays are capable of migrating and causing permeability damage when a formation is permeability damage when a formation is contacted by a foreign water. Normally, waters foreign to a formation alter the ionic environment which is responsible for the clays being dislodged from their original positions. A change in the swelling or water retention of montmorillonite and mixed layer clays enhances their probability of migrating. Thus, any time a clay is present, it can be assumed that permeability damage may occur if the proper precautions are not observed. The degree of damage will depend upon the concentration and types of clays present, their relative position in the rock and the severity of the ionic environmental change. Clay problems should be considered by the well operator in the initial planning of the well. Muds and cement planning of the well. Muds and cement slurries can be treated with potassium chloride to minimize damage when fluid is lost to the formation. The selecting of the correct perforating fluid is also important. Stimulation treatments should be redesigned to fit formation conditions as nearly as possible. Chemicals such as potassium chloride or ammonium chloride may be added to water to minimize total environmental changes when water is used in fracturing procedures. Surfactants are present in most stimulation fluids and these chemicals are capable of being adsorbed by clays and other silicate surfaces which may influence the effectiveness of a treatment. The kind of surfactant to use in any stimulation procedure should be of the type that leaves all procedure should be of the type that leaves all silicate surfaces water wet. An oil wet formation can trap water in the pores to greatly reduce the flow of oil or gas.