Enhanced Oil Recovery. Chemical Flooding. ENHANCED OIL RECOVERY Cairn India Limited.

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1 Enhanced Oil Recovery Chemical Flooding.

2 2 3 Enhanced Oil Recovery (EOR) is a term for special techniques to increase the amount of crude oil that can be extracted from a field, over and above conventional primary depletion or basic waterflooding which typically will recover 20-40% of the stock tank oil initially in place (STOIIP). Using typical EOR methods, an additional 10-20% of STOIIP can be extracted from a field. For example, polymers can be used to increase the viscosity of injected water, forcing it to move into regions of the reservoir that would not be contacted by plain water; resulting in a more efficient flood and sweeping more oil to the producers. Additionally, small amounts of detergent-like surfactants can also be Oil Rate Initial targeted plateau production Q EOR Opportunity in Rajasthan Schematic MBA Water Flood Left: Water fingers through the oil as it moves from injection (I) to production (P) well due to adverse viscosity effects Right: With polymer or ASP, little or no fingering is evident as viscosities are similar, improving sweep efficiency and oil recovery injected with water and polymer; these soaps help scrub more oil out of the rock wherever the water goes; further enhancing oil recovery. 10 Years EOR Potential to extend and enhance plateau The importance of EOR for the Mangala field (and subsequently for Bhagyam and Aishwariya) was realized soon after its discovery in The field is expected to produce around 35% of STOIIP over thirty years of conventional waterflood operations. In part, due to its moderate oil viscosity, this oil production will be accompanied by large volumes of associated water production, as the less viscous injected water tends to finger or channel through the oil, arriving at the production wells prematurely. Because of this, under conventional waterflooding, the field can be expected to show moderate to steep oil production decline once it comes off its maximum production plateau. EOR screening studies by reputable international consultants suggested that aqueous-based chemical flooding EOR processes are the most suitable, based on the Mangala rock and fluid characteristics. These chemical processes are aimed at improving the sweep and oil displacement efficiency in the fields. That is, by adding oilfield polymer chemicals, it is possible to make injection water just as viscous as oil, thereby minimizing the tendency to finger through the oil. Thus, more oil will be displaced by the injected water, resulting in increased sweep efficiency. Through the use of alkali and surfactant chemicals, injected water acts almost as soap, helping to wash more oil off the reservoir rock surface, resulting in increased displacement efficiency. Depending on the combination of chemicals used, these processes are called Polymer Flooding or Alkaline Surfactant Polymer (ASP) Flooding. Successful application of these processes should result in significantly increased oil reserves; arrest of production decline; and even less water production as premature arrival of water at production wells is curtailed. All of this is intended to optimize and maximize oil production. Expected impact of successful EOR implementation is schematically depicted in the figure titled EOR Opportunity in Rajasthan. LABORATORY WORK Beginning in 2006 and continuing to date, detailed laboratory studies have been conducted at Surtek Laboratories (USA) and at the Petroleum Engineering Department of the University of Texas (Austin, Texas, USA), to quantify the potential of the various chemical flood processes. The laboratory programmes were developed to evaluate the potential of chemical flood processes for Mangala. Their main objectives were to screen and select chemicals that are suitable for application in Mangala and then to use the best of those in reservoir corefloods to understand process mechanisms; quantify incremental gains over waterflood; and recommend a chemical formulation for pilot testing of the process in the field. Another important objective was to generate parameters specifically required by commercial chemical flood simulators. Results confirm that these processes could significantly increase Mangala s oil reserves. In the laboratory,

3 4 5 Oil Cut % 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Start of Chemical Injection Additional oil from ASP Mangala coreflood result along with pictures of produced effluent (Post waterflood result displayed) recovery of an additional 15% of the STOIIP, as compared to conventional waterflooding, was achieved under polymer flooding. With application of ASP, recoveries were increased by over 30% of the STOIIP. Of course, due to the more heterogeneous nature of the whole field as compared to the smaller samples tested in the laboratories, recoveries in a full-field application can be expected to be somewhat lower. Further studies for the refinement of chemical systems to achieve better results are continuing at the University of Texas, Austin. Results of a Mangala coreflood performed at University of Texas are shown where almost 95% of the total oil in core was recovered. Coreflood recovery nearly 95% of STOIIP EOR PILOT 100% 95% 90% 85% 80% 75% 70% 65% 60% 55% 50% Cumulative Oil % The next step in the evaluation process was to conduct a closely spaced polymer - ASP pilot to test the process under fieldscale conditions. Simulation studies were conducted to design an appropriate pilot to meet the objectives of the study. The company is currently conducting an EOR pilot in Mangala field. Eight wells, including four injectors; one central producer; and three observation wells were drilled for this test. The target zone for the pilot is the uppermost unit of the Mangala reservoir which contains around 45% of the total STOIIP. The pilot design involves conducting a waterflood followed by a polymer flood, and then later followed by ASP flood to help quantify the incremental recovery benefits from each process in the pilot area. Water injection in the pilot, which started in December 2010, was completed in July 2011 after the water-cut in the field rose to about 70-75% level. Polymer injection was then started through newly built facilities in August Polymer flood response was as per expectations with the watercut declining to 30% levels and staying at low levels for 4-5 months, indicating that the success of polymer injection is improving the sweep efficiency within the pilot and thereby enhancing oil recovery. In addition to continuous monitoring and evaluation of the production & injection parameters at the pilot wells which help in estimating the oil recovery, there are three logging observation wells inside the pilot area, where the changes in oil saturation as a result of flooding in the pilot are periodically measured providing a direct assessment of the in-situ conditions and the progression of the flood front. The next phase of the pilot operations EOR Pilot Schematic

4 6 7 EOR Pilot Result indicating increase in oil rate and decline in water-cut with start of polymer injection is to inject an ASP slug and evaluate the incremental recovery benefits over the polymer flood process. The pilot will conclude after the completion of the ASP phase. Preparations for next phase of ASP flooding are in progress currently. MANGALA FULLFIELD POLYMER APPLICATION Based on the positive response, a fullfield polymer flood development plan has been prepared for Mangala comprising more than 100 new injectors to be drilled from 15 existing well pads. The data and experience gained from the pilot has been used to model, plan and optimize the full-field development concept. A Central Polymer Preparation Facility (consuming about 190 tonnes of polymer per day) with an extensive distribution system is now planned on an existing, old well location (centrally located in the field) to provide each well pad with high concentrate polymer solution for dilution to the required level for each individual well on each well pad. The polymer will be transported in granular form in dedicated closed containers to the Barmer area by train. Strategic storage has been projected at the siding station approximately 30 km away from the field. It is expected that the facilities will be operational for first polymer injection in 2014/15. Following the implementation at Mangala, Cairn India intends to implement chemical flooding in Bhagyam and Aishwariya as well. The current assessment of the EOR resource base is more than 300 mmbbls The 3 MBA Fields Fatehgarh Reservoir >2 billion boe STOIIP under development Reserves and Resources >1.2 billion boe Rajasthan Basin Reserves and Resources Gross 2P reserves Chemical EOR resource potential 636 MMbb >270 MMbbl of incremental recoverable oil from the three MBA fields. The figure below shows the significant potential for EOR in the MBA field. Saraswati, Raageshwari Oil, Raageshwari Gas 22 Other Fields Ongoing work to monetize resource and reserves from MA Barmer Hill and remaining fields

5 CAIRN INDIA LIMITED Cairn India is one of the largest independent oil and gas exploration and production companies in India with a market capitalisation of ~ US$ 10 billion and the fastest-growing energy company in the world as adjudged by the Platts 2012 and 2013 Rankings. Cairn India operates more than 25 per cent of India s domestic crude oil production. Through its affiliates, Cairn India has been operating for more than 15 years playing an active role in developing India s oil and gas resources. To date, Cairn India has opened 4 frontier basins with over 40 discoveries, 28 in Rajasthan alone. The Mangala field in Barmer, Rajasthan, discovered in January 2004, is the largest onshore oil discovery in India in more than two decades. Mangala, Bhagyam and Aishwariya fields major discoveries in Rajasthan block have gross ultimate oil recovery of over 1 billion barrels from primary, secondary and enhanced oil recovery (EOR) methods. Cairn India has a portfolio of 9 blocks - one block in Rajasthan, two on the west coast and four on the east coast of India, and one each in Sri Lanka and South Africa. Oil and gas is currently being produced from Barmer, Ravva and Cambay. 3rd & 4th Floors, Vipul Plaza, Sun City, Sector 54, Gurgaon , India Follow us: Twitter LinkedIn - company/cairn-india-ltd YouTube - cairnindialtd SlideShare - cairnindia