DEVELOPMENT PRACTICES FOR OPTIMIZED MEOR IN SHALLOW HEAVY OIL RESERVOIRS

Abstract

The objective of this research project is to demonstrate an economically viable and sustainable method of producing shallow heavy oil reserves in western Missouri and southeastern Kansas, using an integrated approach including surface geochemical surveys, conventional MEOR treatments, horizontal fracturing in vertical wells, electrical resistivity tomography (ERT), and reservoir simulation to optimize the recovery process. The objective also includes transferring the knowledge gained from the project to other local landowners, to demonstrate how they may identify and develop their own heavy oil resources with little capital investment. The first year period was divided into two phases--Phase I and Phase II. Each phase was 6 months in duration. Tasks completed in first six month period included soil sampling, geochemical analysis, construction of ERT arrays, collection of background ERT surveys, and analysis of core samples to develop a geomechanical model for designing the hydraulic fracturing treatment. Five wells were to be drilled in phase I. However, weather and funding delays resulted in drilling shifting to the second phase of the project. During the second six month period, five vertical wells were drilled through the Bluejacket and Warner Sands. These wells were drilled with air and logged openhole. Drilling locations were selected after reviewing results of background ERT and geochemical surveys. Three ERT wells (2,3,4) were arranged in an equilateral triangle, spaced 70 feet apart and these wells were completed open hole. ERT arrays constructed during Phase I, were installed and background surveys were taken. Two wells (1,5) were drilled, cased, cemented and perforated. These wells were located north and south of the three ERT wells. Each well was stimulated with a linear guar gel and 20/40 mesh Brady sand. Tiltmeters were used with one fracture treatment to verify fracture morphology. Work performed during the first year of this research project demonstrates that surface geochemical methods can be used to differentiate between productive and non-productive areas of the Warner Sand and that ERT can be used to successfully image through the Warner Sand. ERT work also provided a background image for future MEOR treatments. Well logs from the five wells drilled were consistent with previous logs from historical coreholes, and the quality of the formation was found to be as expected. Hydraulic fracturing results demonstrated that fluid leakoff is inadequate for tip screenout (TSO) and that a horizontal fracture was generated. At this point it is not clear if the induced fracture remained in the Warner Sand, or propagated into another formation. MEOR treatments were originally expected to commence during Phase II. Due to weather delays, drilling and stimulation work was not completed until September, 2003. Microbial treatments therefore will commence in October, 2003. Phase III, the first 10 months of the second project year, will focus primarily on repeated cycles of MEOR treatments, ERT measurements and well pumping.