Extended Reach Wells in Unconsolidated Sands in Bolivia

Abstract

The objective of this Technical Paper is to show the experiences and challenges in the design and execution of an extended reach well in unconsolidated sands carried out by Pluspetrol Bolivia Corporation in the Tacobo-Curiche Area. Due to surface obstacles (bed of the Rio Grande river) was proposed the drilling of a directional well which trajectory had to pass through two objectives: 1570 m Horizontal Displacement (HD) at 770 mTVD and 2345 mHD at 1171 mTVD, with the following conditions: 1st.- unconsolidated sands, 2nd.- channel of the river and 3rd.- superficiality of the objectives. The main objectives set for this project were: Reach the targets in the required position.Provide well quality to obtain reservoir data.Provide a well capable of being tested and produced in multiple thin layers of reservoir. These objectives raised technical challenges in different areas of well construction, i) curve construction in the first section with significant Dog Leg Severity (DLS) in well of 17½" and in unconsolidated sands, ii) complex trajectory type "S" with HD/TVD ratio> 2; iii) collision with existing well; iv) well stability and v) cementing job for high angle well, with long areas of interest and interspersed water levels. To face these challenges, it was necessary to achieve a balance between hole cleaning, bit hydraulics, Rate of Penetration (ROP) and BHA directional response, being of vital importance for this, thixotropic mud, its density and the management of drilling parameters. The challenges and the way to face them will be developed in this Technical Paper together with the results obtained.