Reservoir Development Consulting offer's pressure diagnostic design and analysis exceeding the capabilities of all other companies in the industry. For example, Reservoir Development has demonstrated theoretically and in the field that fracture-injection/falloff data can be generated using compressible fluids, like nitrogen. Unlike other analysts, Reservoir Development doesn't rely on conventional after-closure analysis where pseudolinear or pseudoradial flow regimes must be identified to quantitatively evaluate the falloff data.
Reservoir Development Consulting developed new type curve matching methods for analyzing injection/falloff and fracture-injection/falloff diagnostics. Type curve analysis, where the observed pressure data and derivatives are matched to constant-rate type curves, is the preferred analysis method. Conventional after-closure analysis requires identifying portions of the falloff data for analysis with specialized methods. Type curve analysis, including a new negative 2nd derivative type curve, allow all of the data to be analyzed during fracture(s) closure (storage) and through the end of the falloff.
With conventional analysis, bilinear, linear, or radial flow regimes must be identified for analysis; however, in most low perm reservoirs, bilinear and radial flow are virtually never observed. Linear flow is sometimes observed, but requires the creation of a long, infinite-conductivity fracture and requires knowing the created fracture half-length to estimate permeability. Type curve methods remove the limitations of conventional analysis.
Type curves can be generated for all reservoir models--radial flow with wellbore storage and skin, infinite-conductivity fracture, finite-conductivity fracture, damaged fracture, multiple fractures, bounded reservoirs, etc. Two examples are shown in the figures.
Pre-frac Nitrogen Fracture Injection/Falloff Test
The first example is a pre-frac nitrogen fracture-injection/falloff test. The upper figure shows the pressure during the nitrogen injection and falloff, and the second figure shows a match of the observed data to pressure, semilog derivative, and negative 2nd derivative type curves for radial flow with wellbore storage and skin.
Post Frac Restimulation Candidate Diagnostic
Underperforming wells or layers in a multilayer completion may benefit from restimulation provided a treatment is designed to remediate the issues decreasing productivity. Diagnostics can identify the problems limiting production and provide reservoir properties for evaluating the benefit of restimulation. The lower figure is from a post-frac nitrogen fracture-injection/falloff diagnostic in a layer producing less than 10 mcf/d. The data are matched to a finite-conductivity type curve, and the diagnostics determined that the layer was effectively stimulated and that restimulation was unnecessary.
Reservoir Development Consulting continues to refine and develop the state-of-the-art methods for pressure diagnostics. Simply put, Reservoir Development is a pressure diagnostics expert.
Sandstone nitrogen-injection/falloff test type curve match.
Refracture-candidate nitrogen injection/falloff type curve match - finite-conductivity fracture.
Pressure Transient Analysis with Multiple Fractures and Horizontal Wells
Reservoir Development also can perform specialized analysis of pressure transient tests in wells where complex fracture patterns are observed. Obviously, well test data influenced by complex fracture patterns will not necessarily look like well test data for a well producing from a single planar fracture. Standard well test analysis packages do not include models of complex fracture patterns.
An example vertical shale well pressure buildup test type curve match is shown. The observed data match a trifracture model with very low fracture conductivity. The type curve match indicates a primary fracture half length of 3,291 ft, a secondary fracture half length of 823 ft, and a diagonal fracture half length of 2,715 ft. The fracture dimensions are consistent with maps of microseismic events recorded during hydraulic fracturing in offset wells. Consequently, a well test can be used to determine the degree of complexity and the stimulated reservoir volume when microseismic data is not available.
Horizontal Wells. Reservoir Development has developed a pressure transient solution for multiple longitudinal, transverse, and/or fractures at oblique angles to a horizontal wellbore. The new solution suggests pressure transient data can be used to determine the effective producing length of the lateral and the number of fractures contributing to production.
Barnett shale pressure buildup complex multiple fracture type curve match.
Craig, D.P. and Blasingame, T.A.: “Application of a New Fracture-Injection/Falloff Model Accounting for Propagating, Dilated, and Closing Hydraulic Fractures,” paper SPE 100578 presented at the 2006 SPE Gas Technology Symposium, Calgary, Alberta, Canada, 15-17 May 2006.
Barree, R.D., Barree, V.L., and Craig, D.P.: “Holistic Fracture Diagnostics,” paper SPE 107877 presented at the 2007 SPE Rocky Mountain Oil & Gas Technology Symposium, Denver, Colorado, 16-18 April 2007.
Craig, D.P. and Blasingame, T.A.:"Constant-Rate Drawdown Solutions Derived for Multiple Arbitrarily-Oriented Uniform-Flux, Infinite-Conductivity, or Finite-Conductivity Fractures in an Infinite-Slab Reservoir," paper SPE 100586 presented at the 2006 SPE Gas Technology Symposium, Calgary, Alberta, Canada, 15-17 May 2006.
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