Abstract

Due to the development of new tooling and the use of sound engineering coil tubing deployed thru-tubing gravel packs have become an economical and efficient means for the control of sand production.

The authors of this paper have been involved with over forty such jobs in the past two years. The goal of this paper will be to convey the experiences gained in both newly developed component technologies and applications engineering that has been responsible for their overall success.

Introduction

Coil tubing deployed thru-tubing gravel packs have become a common practice in the oil and gas fields of the Louisiana and Texas gulf coast. These non rig workovers allow for cost savings of ten to twenty percent of comparable rig workovers necessary to repair or install cased hole gravel pack systems. However, because of a relatively low level of reliability often these cost savings have not been realized. Through the author's experiences this reliability problem is a result of two major sources,

  1. inadequate component technologies

  2. poor applications engineering related to job planning and supervision.

Component technologies involved with thru-tubing and slim hole gravel packing have until recently been very limited. Over the past two years a new coiled tubing deployed gravel pack system, (one trip circulating thru-tubing gravel pack system), has been development and first employed on offshore Louisiana oil and gas wells. All of the cases listed and discussed in this paper have utilized this system. Due to the similarities between this system and today's current cased hole gravel pack systems many techniques and practices developed for cased hole gravel packing can easily be applied or modified for thru-tubing operations.

Several types of CT deployed Thru-tubing gravel packs have been listed in this study (Table 1). The most frequently experienced has been the installation of a thru-tubing gravel pack in wells that contain no means for sand control. Over fifty percent of the jobs listed in this study are of this type. The second most commonly experienced job type has been for the repair of failed cased hole gravel packs. This job type comprises about thirty-five percent of the total listed in this study. A variety of other types of thru-tubing and slim hole gravel packs were experienced during this study however only the most common are discussed.

Component Technologies

Until recently component systems used for thru-tubing or slim hole gravel packs have been limited to two basic types (1) the over the top squeeze type and (2) the wash down method.1

Over the Top Squeeze.

The over the top squeeze method of thru-tubing gravel packing has been used for several years. This technique however is limited to applications involving short production intervals, usually less than thirty feet in length and low angles of well bore deviation under, forty-five degrees.1

Over the Top Squeeze.

The over the top squeeze method of thru-tubing gravel packing has been used for several years. This technique however is limited to applications involving short production intervals, usually less than thirty feet in length and low angles of well bore deviation under, forty-five degrees.1

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