Start-up of a TSO Fracturing Campaign in a Shallow, Heavy Oil Steamflood
Authors: Malone B.P. , Moran J.H. , Nasution R. Dj. , Putra P.H. , Thurston F.K. 
Published: December 2007

This paper describes the steps taken in the last five month period to implement the full scale use of tip screenout (TSO) fracturing in the Duri Steamflood (DSF) Field of Central Sumatra, Indonesia. The goals of this re-completion project are to maximize productivity of a cased hole completion and to provide sand control. A stable, high conductivity proppant pack, is designed to act as an "external screen" in this unconsolidated formation.

High proppant concentrations of 18 pounds of proppant added per gallon of fluid (ppa) are being utilized. Curable Resin Coated sand (RCS) slurries and 180 degrees perforation phasing are showing good results in preventing sand/proppant production in this sand formation.

This paper will report the early successes and observations that have been seen in the first 30 re-completions of a planned 1000.

Introduction

Screenless TSO completions are a new alternative technology to re-complete wells in DSF to add the Rindu formation. These completions consist of a TSO fracturing, utilizing RCS as the proppant. These treatments are performed without a gravel pack screen in the well.

The Rindu formation consists of four sand/shale groups. Total Sand and shale thickness varies across the recompletion area from 20 – 80 feet. This formation had not been previously developed as a steamflood zone because it was a secondary target. The initiation of steam injection occurred in the deeper primary zones, Pertama and Kedua (PK) Sands in 1985. The depth of the Rindu Sands vary between 300 to 500 ft (Figure 1). Porosity's and permeability's vary from 30 to 35% and 1300 to 3000 md, respectively. The oil is 22 API gravity and 160 cps at initial conditions. Current pore pressures range from 85 to 136 psig. Treatment pressure matching indicates the Young's Modulus is 200.000 psi or less.

TSO fracturing technology was successfully tested on four cased hole wells in the Rindu Steam Injection Pilot area during December 1995 and January 1996. Post-fracture production tests in the pilot wells demonstrated fluid productivity increases of 28% to 162%.

TSO Fracturing Full Scope Implementation

The DSF Field currently has 4000 wells. The Rindu Sand is the main target of the vertical expansion project of the steamflood which will involve re-completions in over 1000 wells. Based on the results of TSO pilot project, fracturing stimulation is the planned completion for approximately 60% of these wells. Eight wells have been fracture stimulated with gravel pack screens in place using conventional gravel (Frac & Pack). This is a planned alternative completion and these eight wells are also being evaluated.

The majority of the PK producers are completed with 10 3/4 inch casing to accommodate large diameter screens and high volume rod pumps. In many of the PK open hole gravel pack (OHGP) completions, the top of the gravel pack screen overlaps the Rindu interval. The top of the liners are revised to expose the Rindu completion interval. The liner top of the lower PK completion is then isolated to allow a screenless fracture completion of the Rindu Formation. The Rindu production is then co-mingled with the PK's. Separate Rindu, slim hole, steam injectors are being drilled within the existing production patterns to provide steam. These injectors will be drilled and made operational during 1997.

Completion Selection

Three cost analyses were done for the completion:a screenless fracture completion (TSO) using RCS sand;-a fracture stimulation with a gravel pack screen in place using locally obtained gravel (Frac & Pack) and;

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