Bottom Hole Compression
Bottom Hole Compression or Conventional drill stem tests use compression-set packers set above the formation, with tail pipe (drill collars or hevi-wate drill pipe) below the packers to the bottom of the hole. Placing weight on the tool string compresses the packers creating a seal before hydraulic valve opens, allowing the formation to flow.
The formation is flowed for a specified time period, after which the drill pipe is rotated five turns to the right to close the shut-in tool for a specified shut-in period (build-up). Five more right-hand rotations opens the shut-in tool for a second flow. Five more rotations (total 15) closes the shut-in tool for a final build-up. The tubing/drill pipe contents can be reversed out of the string though the pump-out-sub before pulling up on the drill pipe to close the Downhole Sampler and release the compression packers.
Benefits
- Test on penetration while drilling – When oil or gas shows occur while drilling, pull the drilling BHA and run in hole to immediately test the formation with the DST BHA before mud invasion formation damage.
- Trip Dry – Run in hole with dry pipe or air gap to maximize underbalance for inflow testing Deliverables:
Deliverables
- Formation Pressure (P*) and temperature charts for Pressure Transient Analysis (PTA)
- PTA Deliverables: Permeability (k), damage/skin, Deliverability, Flow Regime, Reservoir Boundaries
- Production Rate - Gas and liquid
- Downhole reservoir fluid samples
Specifications
- Packer pressure differential: 5,000 PSI
- Absolute pressure: 8,000 PSI
- Temperature: 140 C / 284 F
- Hole sizes: 6.125” to 12.25”
- Wash-out: 15%
- Deviation: up to 45o
- Interval size: unlimited
Find information on any of our DST services.
Solutions recently used in geothermal
