Raageshwari Gas Terminal. Natural gas recovery- Zero Flaring During Milling Operations

Transcription

1 2018 Vedanta Limited Cairn Oil & Gas Raageshwari Gas Terminal Natural gas recovery- Zero Flaring During Milling Operations

2 2018 Vedanta Limited 2 INTRODUCTION RDG is Cairn India s gas field in Rajasthan. Tight gas reservoirs are hydraulically fractured to increase recovery rates. Plugs are installed in gas wells to isolate different sub surface reservoir units. In Raageshwari Deep Gas field development, 15 gas wells were hydraulically fractured and later had plug milling During milling, metallic debris comes back on surface with water, oil condensate and gas. Hence usually gas can t be taken straight in to production system. Produced gas has to be flared.

3 2018 Vedanta Limited 3 Problem Statement Gas produced during milling is flared or burnt. Produced gas cannot be taken into production system due to presence of metallic debris in flowback Objective ZERO FLARING DURING MILLING OPERATION

4 2018 Vedanta Limited 4 Initial setup during milling Flowback - Sand + Hydrocarbon Gas flare ~ 8 MMscf Emergency shut down 1. Gas + Debris 2. Gas + proppant GAS WELL Choke manifold to control gas rate Sand filter 3 phase separator Production Header to Processing plant On site condensate storage Waste water Pit

5 2018 Vedanta Limited 5 Challenges with initial setup Estimated gas burnt/flared per well during this operation is 8 MMSCF. Gas flaring GHG emissions / Revenue Loss. At the end of milling operation, the stored condensate is to be transferred from onsite storage tanks to production facility that takes another 3-4 days. Suboptimal use of associated resources during this transfer. Un-stabilized Condensate handling issues.

6 2018 Vedanta Limited 6 Final setup during milling Fluids in system - metallic debris + Sand + Hydrocarbon Emergency shut down Zero flaring Sand filter GAS WELL Choke manifold to control gas rate 3 phase separator Production Header to Processing plant Debris catcher Waste water Pit

7 2018 Vedanta Limited 7 Road map for final setup: Debris catcher was incorporated in setup to separate debris and proppant. Detailed risk assessment carried out for the amended plan among all stakeholders. Agreement to never bypass sand exclusion systems debris catcher and sand filter to ensure clean gas. Maintained the differential pressure across the test separator to allow the condensate flow into the production header. Amendment in SOP for handling surges back in production facility. PSIT introduced in the final setup for additional process safety. Frequent sampling ensured at well pad to check any presence of debris.

8 2018 Vedanta Limited 8 Challenges faced and action taken Challenge Big chunks of cast iron generated during milling could have damaged production system. Action A high pressure vessel was used as debris catcher to separate debris by virtue of centrifugal and gravitational forces. Metallic debris Debris catcher

9 2018 Vedanta Limited 9 Pictures of zero flare set up Coiled Tubing Unit engaged in bridge plug milling in a gas well. A debris catcher. Gas and condensate flowing into Production facility.

10 2018 Vedanta Limited 10 Achievements.. Established a new benchmark for future milling operations. Cost Overall Cost saving by Zero Flaring : ~ 0.96 MM USD. Improved Utilization of heavy rental well services units : 30% rental savings. Environment Reduction in Environment pollution: Tons of CO 2 Equivalent. Reduce impact on community and bio-diversity. Safety Handling of light condensate is avoided. Accomplished entire fracturing milling campaign with zero HSE incident.

11 2018 Vedanta Limited 11 Replicability & Repeatability REPLICABILITY Hydraulic fracturing in tight gas wells is a prevalent practice in oil and gas industry. The zero flare setup can serve as a role model to other oil and gas companies involved in similar operations. REPEATIBILITY Other companies can also use same set-up to conduct zero flaring milling operation. LIMITATION This technique might not be used during exploration phase of an oil and gas field as production facilities investments are not done at such early phases.

12 2018 Vedanta Limited 12 Thank You