Maximising the Opportunity in Multi-Layered Tight Sand Reservoirs in a Mature Field by Hydraulic Fracturing: A Case Study of Tight Sand Development Project in Thailand
Authors: Suppachokniun Theerapat , Wantawin Marut , Kiatrabile Thanita 
Published: October 2018

After decades of conventional oil production from multi-layered reservoirs of Phisanulok basin in Thailand, the streamlined implementation of hydraulic fracturing following the successful pilot has recently made production from tight resources economically viable. This paper presents the strategic expansion of hydraulic fracturing activities that has evolved to full field implementation for the first time in Thailand. The adopted practices and improved oil production associated with the project ultimately delivers sustainable development of tight oil reservoirs.

The pilot fracturing campaign implemented after years of subsurface and geomechanics studies have been evaluated. The attractive outcome indicates the oil gain almost eight times the Estimated Ultimate Recovery according to decline curve analysis, leading to the asset scheme strategically developed for unlocking tight oil potentials from multi-layered reservoirs by hydraulic fracturing applications. The development strategies including (1) the continual fracturing activities in the proven areas, (2) the implementation in new formations, and (3) the revival of the existing non-productive wells are comprehensively discussed, followed by the fundamental considerations for design and implementation of hydraulic fracturing along the actual process.

As a result, hydraulic fracturing have becomes the key technique serving tight sand development scheme and will be continuously implemented in larger scale to facilitate the target oil production, making the project a dynamic operation. Prudent subsurface management model and deliberate project planning and execution are inevitable. Oil gain was estimated from tight reservoirs mainly in the area where technology has been proven, and from the unproven areas and formations. Available geomechanical model in the proven area has been revisited, and updated to enhance the engineering design of fractures. Additional data acquisition approaches, including acoustic logs, have been proposed to obtain more understanding in unfamiliar areas and formations. Asset drilling schedule and hydraulic fracturing plan have been optimally arranged in a way that the dedicated wells maximize overall asset production. Essentially, the selection of candidate wells becomes the critical part of the project. Many existing wells encountered tight formation, but they are no longer economically viable due to rapid production decline. Based on geological evidences, production data, and well integrity status, the selected candidates were strategically included in the project scope, which also supports idle well restoration program.

Key elements of the hydraulic fracturing project in Thailand from the success of pilot campaign to the first-ever full-scale implementation in effectively and sustainably developing tight, multi-layered reservoirs of Phitsanulok basin are captured. Subsurface management scheme; operation plan and execution; fracture design and treatment technique optimization being applied fieldwide presented can be practical model useful for the operators to maximize the opportunity in tight reservoir portions, on the steps toward the sustainable future.