Determining Multilayer Formation Properties from Transient Temperature and Pressure Measurements

Abstract

The Multilayer Transient Test is a well-testing technique designed to determine formation properties in multiple layers, and it has been proved effective during the past two decades. To apply the Multilayer Transient Test, a combination of rate profiles from production logs and transient rate and pressure measurements are required at multiple surface rates. Therefore, this method can be time consuming and may involve significant The inverse model is formulated by incorporating the forward model to solve formation properties using nonlinear least-square regression. For the hypothetical cases, the proposed new multilayer testing method has successfully been applied for investigating formation properties in commingled multilayer reservoirs. Layer iv permeability, damaged permeability, and damaged radius can be uniquely determined using single-point transient pressure data and multipoint transient temperature data at appropriate locations. Due to the proposed data acquisition scheme, only one surface flow rate change is needed to implement this testing approach, which significantly reduces the test duration compared to the standard multilayer transient testing approach using a series of flow rate changes. Of special interest, this is the first test design that shows promise for determination of the damaged radius, which can be useful for well stimulation design. In addition, temperature resolution, data noise, and data rate impacts have been studied along with a data filtering approach that enable selection of suitable pressure and temperature sensor technologies for applying the new testing method.

Determining multilayer formation properties from transient temperature and pressure measurements in gas wells with commingled zones

“…During the regression procedure, the LevenburgeMarqurdt algorithm (C.T. Kelly, 1999;Weibo Sui, 2009) is applied to renew the iteration parameters.…”

“…Using the generated observation data and the initial guesses of the regression parameters (k, k s , and r s ), we could calculate the true values of formation properties by doing nonlinear regression. The detailed interpretation procedure can be referred to our previous work (Sui et al, 2008). The true values, initial guesses, and final regression results for both examples are shown in Tables 6 and 7 respectively.…”

“…With the same initial guesses, the inverse results are shown in Table 8 where we can see that the regression accuracy decreases a little bit, but still yield very valuable information. More detailed works on sensor resolution and data noise impacts can be found in our previous work (Sui et al, 2008).…”

“…The reservoir thermal model is derived from the energy balance equation, and has been described in great details in our previous work (Sui et al, 2008), the governing equation is given as…”

“…All the models mentioned above are helpful for the industry to interpret downhole temperature measurements, and most of them addressed the usefulness of the distributed temperature data in flow profiling. Sui et al (2008) a new testing approach and interpretation technique, which was aimed at determining multilayer formation properties (individual layer permeability, damage permeability, and damage radius). The working mechanism of the proposed testing approach is recording the transient wellbore temperature and pressure behavior at some strategic locations in wellbore during a transient flow test.…”