Real-time downhole measurements and interpretation increase the stimulation coverage of a multilateral gas well
Challenge
To effectively stimulate a two-branch multilateral openhole completion in a naturally fractured dolomite formation.
Solution
ACTive Matrix to enable accurate depth placement of the coiled tubing (CT) in each lateral using real-time downhole measurements.
Results
Effective placement of the stimulation and diverting fluid systems and real-time verification of the treatment and lateral entry results.
Costly interventions in Western Canada
An operator needed to increase productivity of two openhole legs in an existing multilateral gas well in a naturally fractured dolomite formation in Western Canada. The well produced 21% H2S and 5% CO2.
Operators in this area face economic challenges in maximizing reservoir contact in these partially depleted carbonate reservoirs. By using a multilateral completion technique, the operators have been able to achieve greater reservoir contact and access isolated reservoir compartments with a minimal increase in well construction cost or complexity.
Coiled tubing, which has been used to access and treat the multilaterals, presents two challenges:
ensuring efficient access and treatment of all laterals during intervention
existing downhole tools to operate in a subhydrostatic environment.
Accurate depth and placement of downhole tools
ACTive Matrix uses downhole measurements and tools and chemical stimulation/diverting fluid systems to meet the challenges. These services enable accurate location and placement of downhole tools in the laterals to control stimulation of the individual legs.
CT was run in the hole to obtain downhole measurements, which were used to stimulate the openhole legs. Acid treatments temporarily diverted and treated the sections of the open hole that otherwise would not have been stimulated. Pre- and post-treatment distributed temperature survey (DTS) data were used to optimize acid placement.
Accuracy and effectiveness of acid stimulation confirmed
Using the more reliable real-time bottomhole pressure measurements rather than surface pressure measurements increased the accuracy and effectiveness of the stimulation treatments.
The initial acid treatment was confirmed and injectivity points and other zones to be opened were identified. Thermal analysis results were used to generate a revised pump schedule that provided details of the appropriate diverter and acid stages, which allowed temporary diversion of the initially stimulated zones and better overall treatment of the multilateral leg.
A final DTS survey confirmed that the treatment successfully diverted the acid and stimulated all the targeted zones.
