Reservoirs which produce under active water drive offer a significant uncertainty towards implementation of Chemical EOR processes. This paper describes a successful pilot testing of ASP process in a clastic reservoir which is operating under strong aquifer drive. The field has ~ 30 years of production history. The objective of the pilot was to understand response of ASP process in a mature reservoir, which is operating under active edge water drive. The build-up permeability of the reservoir is 2-8 Darcy with viscosity~ 50 cP. Salient key observations like production performance, incremental oil gain, polymer breakthrough etc. are discussed in this paper after completion of the pilot.
On the basis of laboratory study and simulation, ASP pilot was implemented in the field in 2010.The pilot was designed with single inverted five spot pattern and one observation well. The pilot envisaged injection of 0.3 pore volume (PV) Alkali-Surfactant-Polymer (ASP) slug, 0.3 PV graded polymer buffer followed by 0.4PV chase water. The pilot was meticulously monitored for production performance and breakthrough of chemicals. All the pilot producers have more than 20 years of production history. Base oil rate and water cut were fixed before start of the pilot, on the basis of test data which was used to monitor pilot performance. Interwell Tracer Test (IWTT) was conducted before starting of ASP injection so as to understand sweep in the pilot area. In addition, quality of injection water and chemical concentration in ASP slug was checked regularly to ensure best quality.
Significant response of the pilot was observed within 15 months of the start of the pilot which was published in 2012. This paper aims to describe the learning and conclusion after successful completion of the pilot. ~40-50% jump in oil rate was observed during the ASP injection period which sustained for 12-18 months. However preferential breakthrough of ASP slug in one of the producer impacted the incremental oil gain. The preferential breakthrough of polymer was due to presence of high permeability streaks which was rectified by profile modification job. In addition, strong aquifer movement was experienced during ASP injection which leads to rise in water cut of a pilot well. However, the pilot well was restored through water shutoff jobs. After completion of ASP and mobility buffer, a cumulative incremental oil ~28000 m3 was obtained. Cumulative incremental oil gain is in line with simulation studies prediction. 12-14% decrease in water cut was observed which sustained for ~ 6-18 months. Regular monitoring of produced fluid indicated breakthrough of polymer and alkali in 2-3 producers. During the pilot, produced fluid handling issues like tough emulsion formation, lift malfunctioning etc. was not observed. These collective observation indicated success of the ASP pilot project.
There are very few case histories of successful ASP pilot implementation are available, in which the reservoirs has been operating under active aquifer drive. Learning of this ASP project can be taken forward for expansion of ASP flood and also designing of ASP pilot/commercial projects for analogous reservoirs.
Vajpayee, Mudit (Pandit Deendayal Petroleum University) | Martolia, Ramchandra Singh (Pandit Deendayal Petroleum University) | Chanchlani, Kuldeep (Pandit Deendayal Petroleum University) | Mehta, Mohit (Pandit Deendayal Petroleum University) | Chauhan, Arjun (Pandit Deendayal Petroleum University) | Sodani, Anurag (Pandit Deendayal Petroleum University)
Historically, the co-softhyphen;produced hot water has been an inconvenience and a disposal issue for oilfield operators. This paper focuses on brine or coproduced fluids (hot aqueous fluids produced during oil and gas production) as a potential source for electricity generation, which could be produced from the thermal energy available in the produced fluid. Oil and Gas (O&G) industry today is in possession of thousands of established wells with known temperatures and flows which can be used for producing emissions-free and cost-competitive electricity using binary cycle units.
Power generation from coproduced fluids using a binary-cycle power plant is underway at the Rocky Mountain Oilfield Testing Center in Wyoming and being considered in locations in Texas, Louisiana, Florida, and Arkansas. Although currently there is no electricity generated from coproduced fluids in India, various studies, suggest that the oil and gas fields in the Cambay Basin basin have a promising geothermal gradient of 35-40 °C/km, while (
In this paper, we studied and collated data of Jhalora Field in Mehsana asset of Cambay Basin for coproduction electricity generation and attempt to provide an estimate of the coproduced-water-electricity-generation potential of that field using two different approaches.
The most significant parameters to economic viability for such a project include reservoir temperature as well as total fluid production rate. The reservoir temperature of Jhalora Field is 90-100°C and with produced water flow rate of 5096m3/day, it is a suitable candidate for application of this technology.
Jhalora field, discovered in 1967, is located in the Ahmedabad-Mehsana tectonic block of Cambay basin in India. Reservoir and crude oil properties of all the three main producing sands K-III, K-IV and K-IX+X are quite different. Viscosity of K-IV sand is ~30-50 cp and permeability varies between 1.9 to 8.7 Darcy. Acid number of crude oil is quite high. Water cut is between 80-85%. The mature stage of the Jhalora K-IV with heterogeneous reservoir characteristics and unfavourable mobility ratio makes it an ideal choice for application of chemical EOR technique to enhance the recovery. Based on extensive laboratory and simulation studies one inverted 5-spot pilot was designed. The laboratory studies envisaged additional displacement efficiency of about 23% of Oil Initially in Place (OIIP). Pilot envisaged injection of 0.3 pore volume (PV) Alkali-Surfactant-Polymer (ASP) slug, 0.3PV graded polymer buffer followed by 0.4PV chase water. In order to check preferential movement in the pilot area, profile modification job was done before initiation of pilot. To monitor flood front movement, chemical tracer was also injected.
A meticulous monitoring schedule was drawn. Monitoring is done by measurements of pH, turbidity, Dissolved Oxygen, concentrations of alkali, surfactant & polymer of ASP slug being injected on regular basis. Monitoring schedule also involves fortnightly checking of production rates for each well & weekly testing of water cut. Well head samples from pilot wells are collected on weekly basis and analysis of produced water for presence of tracer & chemical breakthrough is carried out.
In this paper brief results of laboratory investigation leading to implementation of ASP pilot are given. Detailed results of monitoring, problems encountered along-with various steps taken to ensure smooth injection and performance analysis of this pilot so far are given.
Initial results of the ASP pilot are encouraging with additional oil gain of about 47000 bbls after injection of about 0.17 PV ASP slug and expansion of the pilot project is being planned.