Ingeniería De Petroleo

Well Completion Overview


1. Introduction


There are many important aspects related to the production of oil and gas from a petroleum reservoir, but probably none is more important than the actual completion of the well. It has been stated that after a well has been drilled, there is only one opportunity to complete a well properly. No other event in the history of the well is moreimportant. It affects all other the subsequent events related to the well during its entire producing life.


Well completion design is a complex engineering skill, requiring a careful evaluation of the specific well, the producing field and area. This evaluation leads to decisions on how to complete the well. There are many factors that must be considered in the completion of the well.Several important considerations include profitability, simplicity, reliability, safety and anticipated needs. In addition, other basic considerations that must be evaluated include the presence of a reservoir drive, any stimulation requirements, service and workover requirements, and the necessity of secondary and enhanced recovery. There may also be special completion problems, such as water,corrosion, scale, paraffin and erosion. The ideal completion is the lowest cost completion that will meet, or most nearly meet, the demands and requirements placed upon it for most of its producing life.


The evaluation and design procedures, equipment, tools, and processes involved in completing a well are described in this chapter. A detailed description of completion and workover fluidswill then be presented in a subsequent chapter.


Completion activities begin while the well is still being drilled. These activities include a series of pre-completion well evaluations that assist in determining if the well is going to be produced or not. Testing and evaluating a well are probably two of the most important operations conducted during drilling operations. These proceduresbecome increasingly important as drilling proceeds to the target formation(s).


Refer to Figure 1-1: Basic Single Zone Completion Alternatives for an overview of this chapter.

F1-1: Basic Single Zone Completion Alternatives


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2. Well Evaluations


A variety of logs and formation evaluations are conducted to identify and locate potential productionformations.


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Figure 1-2: Logs


2.1 Mud Log


The mud log provides information indicating the sequence of formations and the presence of oil or gas as determined from analyzing cuttings sampled from the shale shaker. It also records the rate of penetration and other drilling variables.


2.2 DST (Drill Stem Test) ReportsThe DST Report provides a pressure and production record of the well prior to its completion. It provides direct evidence about the quality and quantity of any hydrocarbons in the well.


2.3 Core Analysis


At the surface, core samples are initially examined and sent to a central laboratory to be examined by a geologist. A core analysis is then prepared and reported back tothe operator.


2.4 Electric Logs


Electric logs record the conductivity of the interstitial (formation) water contained in the encountered formations. Electric logs can be correlated with other data to develop a more accurate reading of the structure of the formations below.



2.5 Drilling Time Log


The drilling time log provides a record ofthe penetration rate through the formations encountered. They can then be compared with the cuttings evaluations to verify formation thickness, composition, and other pertinent information.


2.6 Other Logs


Many other types of logs are used to provide data, such as radioactivity or radiation logs and acoustic or sonic logs, which help determine the porosity, density, and...