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Abstract

This paper compares sand control methods used in vertical oil and gas wells with a relatively new method used in the first horizontal well drilled in Bolivia. Even though production from the horizontal well has not exceeded that from nearby vertical wells by the expected margin, initial results are encouraging. Production from a zone previously considered low yield has been at previously considered low yield has been at an acceptable level and through a larger choke than normally used in the area. The sand control method utilized may be extended to vertical wells.

Introduction

Sand production in oil and gas wells is one of the greatest problems facing the National Oil Company, Yacimientos Petroliferos Fiscales Bolivianos, (YPFB) in Bolivia. The majority of wells produce from sandstone formations laid down in a continental environment. In this type of formation, sand grains are unconsolidated, or partially bonded to a clay medium similar to natural cement. Fluids introduced to the formation at the perforation stage, high flow perforation stage, high flow velocities and perforation stage, high flow velocities and the presence of formation water cause the wells to produce sand, and consequently, production levels in most of the fields are production levels in most of the fields are severely affected or restricted.

Practical experience in Bolivia has shown Practical experience in Bolivia has shown that without doubt, the mechanical (gravel packing) method of sand control has been packing) method of sand control has been the most successful in vertical wells. Nevertheless, use of perforated pre-packed filter screens as a liner in the first horizontal well has proved to be an effective and economical method to control sand production and could also be used in vertical wells.

Since the majority of Bolivia's reserves occur in unconsolidated formations, it is imperative to determine the best sand control method to optimize hydrocarbon production, extend the productive life of production, extend the productive life of the wells, and hence, substantially improve the profitability of development projects and operation of the fields.

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