Parent-child well spacing and completion design optimization are critical in maximizing returns while minimizing capital expenditures for any projects to develop unconventional reservoirs. The objective of this paper is to present a comprehensive study on the optimization of child-well spacing and completion design through advanced reservoir characterization, complex fracture modeling, and robust reservoir simulation. Finally, an optimal child-well spacing is presented for each parent-well depletion time by considering various completion intensities.
The study began with creating a geological model for the study section, where contains one grand-parent well, a parent-well, and two child wells. Based on the geological model, hydraulic fracturing and reservoir performance models were created and calibrated with well competition and production history spanning three generations of those wells. With the calibrated geological model, intensive simulations consisting of geomechanics analysis, complex hydraulic fracture modeling, and reservoir simulation were conducted to forecast production for 30 years. This process was executed for scenarios involving varying parent well depletion times and child well spacings. Finally, an economic analysis was conducted to assess each scenario. Thus, optimal parent-child well spacings were recommended.
The comprehensive study in this paper indicates that economic performance is maximized by having more producing wells within the shortest period. As parent-well depletion time increases, the optimal child well spacing also increases. Since child-well fracture geometry depends on the production duration of the parent wells, child wells should be spaced further away to mitigate the effects of depletion-induced in-situ stress changes. Additionally, increasing completion intensity does not offset the production enhancements achieved by producing from a greater number of wells. The NPV10 gained from augmenting completion intensity for 2 wells spaced at 1,500 feet in a half-section is $2.1 million (MM), while 4 wells spaced at 660 feet with reduced completion intensity achieved $21.47 MM.
The optimal parent-child well spacings are recommended for different parent well depletion durations. In addition to demonstrating our comprehensive workflow, the results of this paper provide valuable insights into the interactions between parent well depletion, child well spacing, and completion design. By identifying the optimal combination of well spacing and completion parameters to deal with parent-child well situations, operators can enhance recovery, mitigate production interference, and reduce ineffective capitalization. Moreover, the study offers a robust guideline for decision-making that integrates subsurface data, reservoir modeling, and production analysis to advise field development and planning.