Drilling Practices That Affect Formation Damage
Authors: Records L.R. 
Published: December 2007

American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc.
This paper was prepared for the Society of Petroleum Engineers of AIME Symposium on Formation Damage Control, to be held in Houston, Tx., Jan 29–30, 1976. Permission to copy is restricted to an abstract of not more then 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 request 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 time above meeting and, with the paper, may be considered for publication in one of the two SPE magazines.

Abstract
The causes of formation damage are many and varied, but generally are regarded as exposure of the sand to conditions that change the natural fluid content of the formation for some distance from the wellbore.
One of the problems deals with the hydrostatic pressure exerted by the drilling fluid against the. formation fluid pressure. For this reason, minimum mud weight drilling fluids are used as often as is practical. This infers that the static pressures of the drilling fluid column are at least equal to formation fluid pressures. This is necessary in most wells to keep them from pressures. This is necessary in most wells to keep them from blowing out. Another factor that adds mud weight is the swabbing effect caused by the withdrawal of the drillstring, and this means that the minimum mud weight is higher than that needed to contain the formation fluid pressure. Even so, the aim is to prevent high differential pressures from occurring from the hydrostatic pressure of the mud into the producing formation.

Introduction
These precautions are right and necessary, but there is another drilling condition that often nullifies our good intentions and that is the "stand per minute" with which we lower the drill pipe into the hole. Most of us concerned with drilling economics know that hole is being drilled only when the drill bit is on bottom, and the quicker a trip to change bits is made, the lower the cost of drilling. The data for this paper is from a well drilled in South Louisiana that reached a total depth of 15,000 ft, a depth at which trips take a considerable length of time.

DESCRIPTION
We examine the procedure for lowering the drill pipe into the hole as follows.Set slips on 93-ft joint or stand that has just been lowered into the hole.Unlatch the elevators and position them for the derrick man.Run the traveling blocks and elevators up the derrick to catch and pick up a 93-ft stand.Lower this stand into the box threads of the stand in the slips.Screw the two threads together with the chain.Tighten up the thread connection with the tongs - release the tongs.Pick up the stand from the slips - pull the slips.