Camurlu Field Immiscible CO2 Huff and Puff Pilot Project

Abstract

Abstract A pilot project of enhanced oil recovery by CO2 injection has been carried out in Camurlu Field for the first time in Turkey. CO2 gas was injected without using a compressor into selected C-11 and C-22 wells for three consecutive cycles during two years. Five or six fold increases in daily oil production rates of the wells especially within the first few weeks of last cycles have been observed. Field-wide application was decided since it has been understood that better working conditions and better selection of equipment and materials could yield much better results. Introduction Heavy crude oil, 11-12API, produced from Camurlu field created major operational production problems in the past causing abandonment of many wells. Recovery ratio of less than one negatively affected the plans on wild cats and development wells in the field. This phenomena brought the discussion of which EOR project can be applied to increase the recovery. Immiscible CO2 huff n puff pilot project started in Dec. 1984 and continued till Dec. 1986 and applied on two wells. The pilot project was carried out mainly by Turkish Petroleum Corporation, an exploration, drilling and production company. IFP (Inst. Francais du Petrole) participated in the laboratory studies, the reservoir studies, the design of injection and production facilities, the follow-up and the interpretation of the tests. Due to lack of equipment and personnel the project became uneconomical from time to time. However, when the project applied truly, good results were obtained to look forward hopefully. I. GENERAL INFORMATION I.1 - Field Location and Regional Geology The Camurlu Field is located about 50 miles (80 km) south of the city of Mardin in Southeastern Turkey, and lies on the border with Syria. The field was discovered in 1975 and is operated by Turkish Petroleum Corp.(TPAO). Being a Northeast-Southwest anticline it is of interest by its dimensions 3.1 miles (5 km) by 0.62 miles (1 km). Average surface elevation is about 1515 ft (500 m). See Figs. 7 and 8. There are three separated productive formations:The uppermost one, which lies around 4264 - (1300 m) below surface is AltSinan, a light brown, cretaceous limestone. Gross thickness of the formation is about 492 ft (150 m) with top 197 ft (60 m) being heavy oilbearing zone below the gas cap.Approximately 4756 ft (1450 m) below surface, Beloka formation is also a limestone formation having local productive capabilities of heavy oil with a high water cut.The lowermost layer, around 7216 ft (2200 m) deep called Mus formation is a triassic limestone having quite good gas-condensate reserve which contains 73% CO2.The structure contour map of Alt Sinan formation is shown in Figure 2. I.2 - Estimated Reserves Oil in place has been estimated to be 377 × 10(6) STB (60 × 10(6) m) in the proven area for Alt Sinan formation only. Development wells which are newly drilled proved the oil bearing area is much more than the area taken into consideration. Oil in Beloka formation had not been considered in this amount. Original gas in place contained in primary gas cap of Alt Sinan formation found to be 49 × 10(9) SCF (1.38 × 10(9) m3) of CO2 gas.