This paper presents the incorporation of microproppant (MP) in stimulation treatment designs and its effects on well production in the liquids-rich South Central Oklahoma Oil Province (SCOOP) Woodford play. During production, MP can enter and prop open secondary fractures that are too narrow and restricted for even conventional small proppant, such as 100-mesh sand. Descriptions of the MP, area formation, numerical modeling, production results, and offset comparisons are presented.
In unconventional formations, communication between the wellbore and the secondary fracture network, which includes natural fractures and secondary fractures propagated during stimulation, is crucial for improved well production. Perhaps the most difficult objective to accomplish when treating unconventional formations is not just enhancing the number of secondary fractures opened, but increasing the number of those secondary fractures that remain open over a long period of time. During stimulation treatments, MP is pumped during the initial pad stages so it can enter the secondary fractures that are propagated and keep them open when pressure on the formation is relieved during production.
An analysis of treatments and associated numerical modeling conducted within the Woodford play demonstrated the presence of pressure dependent leakoff (PDL), low stress anisotropy, and high net pressures as indications of reservoir complexity. Because of the predicted fracture complexity, a smaller proppant was necessary to prop the narrower secondary fractures. As a result, a series of field trials were conducted to examine the effectiveness of MP for enhancing well production. Comparisons were made between well production where MP was used and offset well production to demonstrate the impact. Production was normalized by pressure and analyzed using square-root time plots. A description of treatment designs used is presented for comparison. The wells in which MP was pumped during the initial pad stages of stimulation treatments demonstrated significant production uplift compared to offset wells.
Additionally, MP demonstrated a secondary benefit, which indirectly manifested in net treating pressure. PDL was believed to be a major contributor to excessively high treating pressures and screenouts in the area. Because the particle size of the MP helped enable better access to the narrower secondary fracture network, it also reduced entry friction associated with PDL. Such a reduction led to lower treating pressures, which subsequently improved placement efficiency of stimulation treatments.