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

Drilling fluid filtration has long been recognized as a factor affecting well productivity. The filtrate can interact with the formations in a number of ways to cause damage. Knowledge of filtration rate (as an indication of depth of filtrate invasion) is important, therefore, in controlling a drilling fluid to minimize productivity damage. productivity damage. This paper presents data for filtration of drilling fluids under simulated downhole conditions, with confining pressures as high as 10,000 psi and temperatures up to 400 F. Depth of filtrate invasion for a particular porosity is calculated from filtration rates of various muds tested at 5000 psi and 300 F.The API high-temperature filtration test is considered as to adequacy for field control in limiting productivity damage. Data are presented comparing paper, steel mesh, and a presented comparing paper, steel mesh, and a porous disc as filter media in the API test. porous disc as filter media in the API test

Introduction

Drilling of a potentially productive formation can be expected to cause some skin damage. The seriousness of that damage depends upon the nature of the formation, the composition and properties of the drilling fluid, and the drilling conditions. Usually the drilling fluid pressure is greater than the formation pore pressure. As a result there may be pore pressure. As a result there may be invasion by whole drilling fluid and solids from the drilling fluid, as well as invasion by drilling fluid filtrate. Various investigations have considered the problem of drilling fluid particle invasion. Attention has also been given particle invasion. Attention has also been given to interaction of drilling fluid filtrate with formation solids and liquids. Generally, these studies have shown that severe damage can be caused by particle and filtrate invasion.

Most of the factors known to affect particle and filtrate invasion are not readily subject to control. For example, high differential pressure often must be tolerated. Scrapping pressure often must be tolerated. Scrapping action of bit and drill string cannot be eliminated.

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