No abstract

The Choke Management has been one of the "hot topics" in Unconventional Reservoirs since the negative impact in using an accelerated flowback has been demonstrated in many documented cases. Modern production practices have migrated from a Choke Management to a Drawdown Management Strategy to improve the control on the effective net stress over the proppant in order to prevent hydraulic fracture conductivity damage and maximize ultimate recovery. The strategy optimization is a complex problem that reservoir engineers are still trying to solve using different tools from empirical observations up to complex reservoir simulators that includes reservoir physics and the most advanced rock mechanics. This work contributes introducing an innovative workflow using a state of the art non-coupled numerical simulator, with the addition of time-steps one-way coupled calculations. The methodology consists in using a commercial reservoir simulator to History Match Completion Treatment Pressures and then Production. Once this first step has been completed, a Pore Pressure Grid is extracted at different times and then used to calculate changes in the minimum stress according to the isotropic poroelastic equation. Finally, the effective net stress over the proppant is calculated. This process is repeated with different Drawdown Management Strategies until the optimization. The complete workflow is introduced in a real case example where a robust dataset was available for a horizontal well. Finally, some assumptions and considerations are discussed and conclusions are extracted from this study.

No abstract

Well spacing and stimulation design are amongst the highest impact design variables which can dictate the economics of an unconventional development. The objective of this paper is to showcase a numerical simulation workflow, with emphasis on the hydraulic fracture simulation methodology, which optimizes well spacing and completion design simultaneously. The workflow is deployed using Cloud Computing functionality, a step-change over past simulation methods. Workflow showcased in this paper covers the whole cycle of 1) petrophysical and geomechanical modeling, 2) hydraulic fracture simulations and 3) reservoir simulation modeling, followed by 4) design optimization using advanced non-linear methods. The focus of this paper is to discuss the hydraulic fracture simulation methods which are an integral part of this workflow. The workflow is deployed on a dataset from a multi-well pad completed in late 2018 targeting two landing zones in the Vaca Muerta shale play. On calibrated petrophysical and geomechanical model, hydraulic fracture simulations are conducted to map the stimulated rock around the wellbores. Finely gridded base model is utilized to capture the property variation between layers to estimate fracture height. The 3d discrete fracture network (DFN) built for the acreage is utilized to pick the natural fracture characteristics of the layers intersected by the wellbores. The methodology highlights advances over the past modeling approaches by including the variation of discrete fracture network between layers. The hydraulic fracture model in conjunction with reservoir flow simulation is used for history matching the production data. On the history matched model, a design of experiments (DOE) simulation study is conducted to quantify the impact of a wide range of well spacing and stimulation design variables. These simulations are facilitated by the recent deployments of cloud computing. Cloud computing allows parallel running of hundreds of hydraulic fracturing and reservoir simulations, thereby allowing testing of many combinations of stimulation deigns and well spacing and reducing the effective run time from 3 months on a local machine to 1 week on the cloud. Output from the parallel simulations are fitted with a proxy model to finally select the well spacing and stimulation design variables that offer the minimum unit development cost i.e. capital cost-$ per EUR-bbl. The workflow illustrates that stimulation design and well spacing are interlinked to each other and need to be optimized simultaneously to maximize the economics of an unconventional asset. Using the workflow, the team identified development designs which increase EUR of a development area by 50-100% and reduce the unit development cost ($/bbl-EUR) by 10-30%.

No abstract