Robust and Flexible Hydrocarbon Production Forecasting Considering the Heterogeneity Impact for Hydraulically Fractured Wells

Abstract

Producing oil and gas from increasingly more difficult reservoirs has become an unavoidable challenge for the petroleum industry as the conventional hydrocarbon resources are no longer able to maintain the production levels corresponding to the global energy demand. As the industrial investments in developing lower-permeability reservoirs increase and more advanced technologies such as horizontal drilling and hydraulic fracturing gain more attention and applicability, the need for more reliable means of production forecasting also become more noticeable. Production forecasting of hydraulically fractured wells is challenging particularly for heterogeneous reservoirs where the rock properties vary dramatically over short distances, significantly affecting the performance of the wells. Despite the recent improvements in well performance prediction, the issue of heterogeneity and its effects on well performance have not been thoroughly addressed by the researchers and many aspects of heterogeneity have yet remained unnoticed. In this paper, a novel empirical approach for production forecasting of multi-fractured horizontal wells is presented in attempt to effectively include the effect of heterogeneity. This approach is based on the integration of hyperbolic Decline Curve Analysis (DCA) and heterogeneity impact factor (HIF). This newly-defined ratio quantifies the heterogeneity impact on the hydraulically fractured well performance and is calculated based on net-pressure match interpretation and post-fracture well test analysis. The proposed approach of decline curve using heterogeneity impact factor (DCH) is validated against data from a Southern North Sea field. The results show a maximum of 15% difference between the outcome of the proposed method and the most detailed three-dimensional historymatched model, for a 15-year period of production forecasts. DCH is a novel, fast, and flexible method 2 for making reliable well performance predictions for hydraulically fractured wells and can be used in forecasting undrilled wells and the range of possible outcomes caused by the heterogeneity.

Modeling the Risk of Commercial Failure for Hydraulic Fracturing Projects Due to Reservoir Heterogeneity

“…In this sense, the HIF parameter was introduced in our previous works [30,31] to account for the degree of the connectivity of fracked wells to more permeable rocks or natural fractures. To define HIF, first, a measurable parameter called Surface Conductivity (SC) was defined, using facture properties, as:…”

“…The gas production from a hydraulically fractured well in a heterogeneous reservoir can be calculated from the following empirical DCH model [30]:…”

“…The unit of D mi is the reciprocal of time. Based on the history match analysis in our previous work [30], the initial production rate, q i and the decline constant, D i were suggested to be corrected for HIF using the following rules: To calculate the produced cumulative gas from a well, Equation (3) should be integrated from the start of production to a specified time:…”

“…In this paper, following our previously-suggested formulas [30] for production forecasting of multi-fractured horizontal wells in heterogeneous tight gas reservoir (the main focus of this study), a highly time-efficient workflow is proposed from which the Risk of Commercial Failure (RCF) due to the impact of reservoir heterogeneity can be evaluated. To achieve this, our suggested gas flow model (decline curve using heterogeneity impact factor, DCH) was incorporated in an economic evaluation platform from which NPV of a hydraulic fracturing job could be calculated for a range of realizations.…”

Economic Feasibility Analysis of Shale Gas Extraction from UK’s Carboniferous Bowland-Hodder Shale Unit

“…A combination of advanced techniques, horizontal drilling and hydraulic fracturing has enabled profitable extraction of shale gas trapped in low-permeability formations [1]. Though, to date, US remains the only country to extract shale gas at a large commercial scale which led to a significant transformation of its natural gas industry, dubbed a 'revolution'.…”