| Description |
Drilling and completion designs have advanced drastically over the last two decades, leading to improved hydraulic stimulation and well production. However, engineers still encounter difficulties addressing the effects of complex natural fractures during hydraulic fracture propagation. Natural fractures can cause unanticipated stress shadowing effects, complex fluid and proppant transport paths, and interactions with hydraulically induced fractures. Proof of concept simulations in this thesis demonstrate that a combination of commercial discrete fracture network (DFN) simulators can be used to qualitatively and quantitatively evaluate stage and cluster placement and improve well design in typical naturally fractured plays. This was possible by 1) analyzing well logging data to develop a discrete fracture network model, 2) simulating fracture network variations resulting from specific design conditions using DFN software packages in tandem, and 3) verifying stimulation and completion design by matching pressure treatment history and evaluating production data acquired from test wells. Three horizontal test wells were used to analyze the effects of different stimulation and completion strategies on accessing pre-existing natural fractures. Formation microimager (FMI) data acquired from one of the wells were used to represent conductive natural fractures intersected by each lateral. The control well contained a four cluster 120 shot per foot (spf) design. The new cluster design consisted of 10 clusters and 10 spf per stage. Following hydraulic fracturing, pressure treatment history matching using as-pumped pumping schedules were used to simulate the effectiveness of various completion and stimulation designs. Simulations for a revised cluster design showed a 15% increase in propped fracture area using the same pump schedule. Simulations results were verified by comparing production data between the three wells over a three-month period. The cumulative BOE production of the limited entry well was similar to the standard wells, but produced 20% less water. Results suggest the new cluster design in this geologic setting has value. The study performed has (1) served as a benchmark for developing an improved understanding of the effects of cluster design complex natural fracture systems and (2) empirically verified that complex fracture modeling simulations can be used in fracture effectiveness for a proposed well. |
