Abstract
This paper presents the incorporation of microproppant (MP) in stimulation treatment designs in the liquids-rich South Central Oklahoma Oil Province (SCOOP) Woodford and its effects on well production. When MP is used, it can enter secondary fractures that are too narrow and restricted for even conventional small proppant, such as 100-mesh sand, to enter and prop them open during production. Descriptions of the MP, area formation, numerical modeling, production results, and offset comparisons are presented.
In unconventional formations, communication between the secondary fracture network, which includes natural fractures and secondary fractures propagated during stimulation, and the wellbore 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 conducted within the Woodford play, and associated numerical modeling, 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 is 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 are made between wells where MP was used and offset well production to demonstrate such impact. A description of treatment designs used is also presented for comparison. The wells where 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 manifests in net treating pressure. PDL is believed to be a major contributor to excessively high treating pressures and screenouts in the area. Because the particle size of the MP enables better access to the narrower secondary fracture network, it also reduces entry friction associated with PDL. Such reduction has led to lower treating pressures, which subsequently has improved placement efficiency of stimulation treatments.
