This work analyzes the feasibility of implementing water injection processes through subsurface connectivity between different formations through communicating wells, allowing the water to flow from a source aquifer to a depleted formation. It presents a 3-dimensional semi-analytical model for estimating water influx in reservoirs with bottom-water drive and analyzing interference between reservoirs when subsurface connectivity is carried out to supply energy from an aquifer. It applies to both finite and infinite aquifers and reservoirs sharing an aquifer. The general solution is obtained by solving the diffusion equation employing Laplace and Fourier cosine transforms and is presented in Laplace space, requiring a numerical inversion method to convert the results to the real space. The functionality of the analytical solution is evaluated with reservoir numerical simulation and communicating well models. Results show that implementing this solution brings notable advantages because the ultimate oil recovery factor improves considerably. Additionally, it delays the water encroachment in reservoirs adjoined to the source aquifer and reduces water production.
The objective of this paper is to develop an easy to use correlation for estimating Biot coefficient. This is important as Biot coefficient plays an important role in solving many practical petroleum engineering problems, including for example, design of hydraulic fracturing jobs and estimation of in-situ closure stress on proppant. The procedure for developing the proposed empirical correlation uses data from various lithologies including limestone, sandstone, shale, marble and granite. Thus, the correlation has application in conventional and unconventional petroleum reservoirs. Use of the correlation requires knowledge of permeability and porosity, data commonly available in petroleum engineering (on the other hand Biot coefficient data is almost never available). The ratio of permeability and porosity, commonly known as process or delivery speed and pore throat aperture (rp35), are input for estimating Biot coefficient from the correlation proposed in this paper. The correlation is useful in those cases where sophisticated experimental work needed for estimating Biot poroelastic coefficient is not available. Testing against various data sets indicates that the proposed correlation provides reasonable results. In the past, methods with different complexity levels have been used for estimating Biot coefficient. These have included, for example, (1) a method that requires knowledge of bulk modulus of the rock mineral and bulk modulus of the skeleton with no fluids in it, parameters that are not usually available for petroleum reservoirs, (2) a method that is based on knowledge of only porosity, (3) a method that is based on knowledge of only permeability, and (4) an approach that simply assumes that Biot coefficient is equal to 1.0 or some other number. The proposed correlation falls somewhere in the middle. It is not as simple as saying that Biot coefficient is equal to 1, or saying that it depends on only porosity, or only permeability. On the other hand, it is not as complex as requiring sophisticated laboratory work of the type mentioned in item (1) above. The novelty of this work is the development of an original easy to use correlation for estimating Biot coefficient in conventional and unconventional (tight and shale) reservoirs based on knowledge of k/ϕ and rp35. The correlation is developed in such a way that it has also application for estimating Biot coefficient in the case of unconsolidated petroleum reservoirs and oil sands. The overall approach allows integration of geomechanics with flow units, geology, petrophysics, and reservoir engineering.
A method is presented for incorporating Biot poroelastic coefficient on Pickett plots. The method allows integration of petrophysical parameters such as water saturation, porosity and permeability with geomechanics through Biot coefficient. Pattern recognition in Pickett plots have been used historically for quick petrophysical evaluation, particularly for determination of water saturation. The procedure involves a crossplot of porosity vs. true resistivity on log-log coordinates. The method presented in this paper allows determination of Biot coefficient from the Pickett plot in addition to determination of standard petrophysical parameters. The method uses a correlation developed for estimating Biot poroelastic coefficient as a function of process speed (the ratio of permeability and porosity) and pore throat aperture (rp35). Results indicate that the proposed Pickett plots permits quick simultaneous estimation of different parameters of interest for a given interval including water saturation, porosity, permeability, pore throat aperture and Biot coefficient. The Biot coefficient correlation works for various lithologies including limestone, sandstone, shales, source rock, marble, granite, unconsolidated and oil sand reservoirs. Thus, the method has application in the case of both conventional and unconventional reservoirs. Key observations based on the proposed Pickett plot include: (1) there is a general tendency for Biot coefficient to decrease as water saturation increases, (2) there is a general tendency for Biot coefficient to increase as porosity, permeability, process speed and pore throat aperture (rp35) increase. It is concluded that the integration of petrophysical parameters and Biot coefficient provides a new valuable tool to assist in the solution of petroleum engineering problems such as hydraulic fracturing and estimation of in-situ closure stress on proppant. The novelty of this work is the development for the first time of an integrated Pickett plot that incorporates petrophysical analysis and Biot poroelastic coefficient.
This paper aims a solution to improve dynamic connectivity between regions in compartmentalized reservoirs. The proposal is to drill horizontal wells whose main objective is to communicate the zones where compartmentalization has been detected. The fluid flow between compartments will occur due to the potential difference existing between them. The flowrate will depend on the petrophysical properties of reservoir, physicochemical properties of fluids and the design of horizontal well. The work develops a mathematical model that represents the potential behavior of each compartment over time when they are communicated through a horizontal well. It considers the special application for gas cap systems and it presents an example, which demonstrates the impact and benefits of this solution. The implementation of this proposal will help exploiting the hydrocarbons reservoir through the existing infrastructure in adjacent regions, thus, reducing or eliminating the requirement of new infrastructure and extending the lifespan of existing infrastructure, thereby maximizing the value and recovery of the fields, which can represent great economic benefits for many oil companies.
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