Objectives/Scope

Raageshwari Deep Gas field located in southern Barmer Basin, in the state of Rajasthan (India), consists of a laminated reservoir where conventional fracturing treatments with a single set of perforations are not economical. In order to improve the project economics, limited entry treatment design (Lagrone, 1963) selected for fracturing. The effectiveness of fluid diversion during limited entry fracture treatment in a laminated reservoir was validated using post injection temperature surveys.

Methods, Procedures, Process

The Limited entry design relies on the pressure drop across the perforations to balance the flow between the various perforation clusters. The treatment design was based on achieving a minimum of 700 psi of perforation friction for adequate diversion between the zones. The perforation friction and number of active perforations was determined using Step Rate/Step Down Tests (SRT/SDT). Post injection temperature surveys were used to confirm fluid entry into the various perforation clusters.

Results, Observations, Conclusions

The following process was applied to more than 90 fracture stages in 15 wells. The fracturing treatments were modeled using log derived mechanical properties and stress contrasts. Diversion into all the clusters was insured by distributing the available perforations based on the predicted fracturing pressure for each zone. Post injection temperature surveys were used to validate the fracturing models. While somewhat qualitative, the post injection surveys did provide valuable insite in some cases, the fracturing simulator predicted fracture growth out of the desired stage area. The post injection temperature survey helped to validate predictions of:

  1. Fracture growth out of the zone of interest

  2. Merging of of the fractures from different clusters.

  3. Separation of fractures from different clusters.

  4. Fractures isolated from perforation clusters

In some cases, post SRT temperature surveys helped justify decisions addition of holes to minimize perforation friction or addition of extra cluster(s) to maximize pay coverage.

Novel/Additive Information

While the use of temperature surveys to estimate fracture height is not new, we believe that this is the most extensive use of temperature surveys in a medium size project incorporating limited entry.

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