The expansion of unconventional resources development has placed emphasis on better understanding of hydraulic fracturing stimulation effectiveness and the area of pay affected by the fracture treatment to optimize well spacing and improve completion and stimulation effectiveness. Existing fracture diagnostic methods such as microseismic monitoring and tiltmeters do not provide information about fracture connectivity to the wellbore. In this paper, we present a chemical tracer flowback based fracture diagnostic and analysis methods to estimate the fractional contribution of each created fracture stage, which is open and connected to the wellbore to help improve field development strategies and provide valuable information on optimal well paths for future drilling and development. The findings out from the stage production contribution profiles using the chemical tracer technology allows engineers to improve stimulation efficiency in multistage hydraulic fracturing horizontal wells applications for completion optimization and production enhancement. Two case histories are presented in which the chemical tracer technology was applied to two horizontal wells. The results of the chemical tracer analysis were correlated to production data, reservoir parameter and other diagnostic tests. The resultant findings from the analysis help evaluate completion and stimulation effectiveness and determine the extent of inter-well connectivity of the fracture network and then used to optimize future completions in the region.
Ibrahim Mohamed, Mohamed (Colorado School of Mines) | Salah, Mohamed (Khalda Petroleum) | Coskuner, Yakup (Colorado School of Mines) | Ibrahim, Mazher (Apache Corp.) | Pieprzica, Chester (Apache Corp.) | Ozkan, Erdal (Colorado School of Mines)
A fracability model integrating the rock elastic properties, fracture toughness and confining pressure is presented in this paper. Tensile and compressive strength tests are conducted to define the rock-strength. Geomechanical rock properties derived from analysis of full-wave sonic logs and core samples are combined to develop models to verify the brittleness and fracability indices. An improved understanding of the brittleness and fracability indices and reservoir mechanical properties is offered and valuable insight into the optimization of completion and hydraulic fracturing design is provided. The process of screening hydraulic fracturing candidates, selecting desirable hydraulic fracturing intervals, and identifying sweet spots within each prospect reservoir are demonstrated.
Ibrahim Mohamed, Mohamed (Colorado School of Mines) | Coskuner, Yakup (Colorado School of Mines) | Salah Mohamed, Mohamed (Khalda Petroleum) | Ibrahim, Mazher (Apache Corporation) | Mahmoud, Omar (Apache Corporation) | Pieprzica, Chester (Apache Corporation)
Unconventional reservoirs have been defined as formations that cannot be produced at economic flow rates or that do not produce economic volumes of oil and gas without horizontal well with hydraulic fracture treatments. Horizontal well fracturing efficiency in unconventional reservoirs is the main factor for the success of developing unconventional reservoirs. The early focus of the industry was on the operational efficiency and during this period, the geometric spacing of perforation clusters adopted as the preferred completion method. Cipolla et al. (2011) presented a case study on the interpretation of production logs from hundreds of horizontal wells. The results indicated that 60% of perforation clusters contribute to production when completed geometrically and completion cost could reach more than 60% of the total well cost. Recently, numerous studies have been undertaken to understand this phenomenon. Increasing the stimulation effectiveness and maximizing the number of perforation clusters contributing to productivity was an obvious area for improvement to engineer the completion design. The uniform initiation and distribution of fractures in each frac stage is very complex because there are many factors affecting the fracture initiation such as stress orientation, heterogeneity, existing of natural fractures, and completion design. This paper presents sensitivity studies investigating the effect of the formation permeability, fracture spacing, fracture half-length, fracture conductivity, flowing bottom hole pressure, and outer reservoir permeability on the well ultimate recovery efficiency by using analytical simulator.