Abstract

A discussion of the overall drilling program that is being used by Chevron U.S.A. in the False River Field is presented with particular emphasis on the various techniques and practices that are being used to accomplish an optimum drilling program.

Introduction

Chevron U.S.A. began drilling at False River, located approximately twenty miles west of Baton Rouge, Louisiana in August 1974, and completed the discovery well in June, 1975. The location is shown in Figures 1 and 2. Since then thirteen 20,000 foot wells have been drilled and drilling is in progress on four other wells.

This paper is presented to show some of the techniques that are being used in the drilling of these wells and to show how the drilling time has been reduced as a result.

Some potential problems that are encountered in this area include lost circulation in the "HET" limestone; sloughing in the Midway shale; abnormal pressures; high pressure shale gas; high bottom hole pressures; high pressure shale gas; high bottom hole temperatures; and CO2 contamination of the mud system. These problems are handled effectively by the mud system and casing program shown in Figure 3.

All of the wells drilled have had some form of data collection and monitoring equipment on the rig to monitor the various drilling parameters and three of the wells utilized an onsite computer. Through the use of the data collected, coupled with the increased ability to closely monitor the drilling operations, drilling times (cost per foot) have been significantly reduced. With the data collected, Chevron has been able to improve bit selection, pin point bit weights and rotary speeds, and improve the point bit weights and rotary speeds, and improve the mud program to minimize drilling times. In addition, the pressure-area method of calculating drill collar weight has been used effectively in the design of bottom hole assemblies to increase penetration, improve bit runs, minimize hole deviation and protect drill pipe.

A comparison of the drilling time is shown in Figure 6 of the first five completed wells to show how the drilling time has been reduced.

The wells were drilled in the following sequence: Number 1 - Alma Plantation #1Number 2 - L. Crochet Number 3 - Popular Grove Number 4 - W. E. Lorio Number 5 - Alma #3

The drilling time to 20,000 feet on Alma Plantation #1 was 150 days, whereas only 90 days were Plantation #1 was 150 days, whereas only 90 days were required to drill the W. E. Lorio to 20,000 feet. On Alma Plantation #1, 16,000 feet were drilled in 90 days while on Alma #3 only 36 days were required. Figure 7 is a plot of rotating time versus depth. It also shows a considerable reduction in rotating time from the first well.

BIT SELECTION

Bits are selected in the normal manner by using the data that has been collected on the previous wells and by close observation of dull bits. The optimum bit program at the present time is to run long tooth seal bearing bits to approximately 10,000 feet. Long insert journal bits are used from 10,000 feet to T.D.

On the first few wells diamond bits were run from 18,500 feet to T.D. because of the long trip times and high temperature which seemed to reduce the bearing life of the journal bits. Recently, however, advances in the manufacturing of journal bits have eliminated this problem and it is more economical to run the journal insert bits to T.D.

WEIGHT ON THE BIT AND RPM

The weight that is run on the bit is the major factor that is different in this drilling operation from most others in the industry in this area.

This content is only available via PDF.
You can access this article if you purchase or spend a download.