No abstract

This paper presents the results of an investigation concerning the development of a reliable and accurate technique for establishing the stabilized deliverability performance of multi-layer commingled systems using multi-rate production log measurements. Both linear and non-linear systems are addressed in this paper, providing a basis for the analysis of reservoirs exhibiting Darcy and non-Darcy flow, respectively. Extension of the conventional Selective Inflow Performance analysis is also presented in this paper to obtain estimates of the formation and well completion properties such as effective permeability, radial flow steady state damage /stimulation skin effect, and non-Darcy flow coefficient. In the specific case where the deliverability performance of a vertically fractured well is considered, estimates of the effective fracture half-length and average fracture conductivity may be derived from the analysis. In cases where the multi-rate deliverability tests are performed under boundary dominated flow conditions, conventional deliverability analysis techniques may also be employed to derive estimates of the reservoir drainage area in addition to the well and reservoir parameters that can be obtained in a transient flow analysis. Applications of the analyses reported in this paper demonstrate the use of the analyses to evaluate the inflow performance measurements of commingled multi-layer reservoirs obtained using multi-rate production logs. Introduction The analysis of the effect of a variable flow rate production history on the pressure transient performance of a well under Darcy flow conditions has conventionally been accomplished using the convolution of the varying flow rate and pressure history of the well to evaluate the transient performance. This relationship is presented in integral form in Eq. 1 and has been utilized for quite a long time1 in the analysis of the transient pressure behavior of oil and gas wells. (1) The dimensionless wellbore pressure at any point in time (tD) is shown to be a direct function of the varying flow rate and pressure history of the well prior to that point in time. The integral relationship given in Eq. 1 can be readily evaluated as a summation of discrete intervals of time for which the flow rate history is assumed to be piece-wise continuous, as a series of constant flow rate steps. This concept is expressed mathematically with Eq. 2 and has commonly been used as the basis for correlating the effects of a variable flow rate history on the pressure transient behavior of a well with the solution for a constant flow rate inner boundary condition. (2) The definitions of the dimensionless variables used in this superposition relationship are given in terms of consistent units for slightly-compressible liquid flow analyses with Eqs. 3 through 5 for time, flow rate, and wellbore pressure, respectively. In the case of an unfractured vertical well, the system characteristic length (Lc) is equal to the wellbore radius (rw).

Locating downhole casing leaks in producer and injector wells is not a complex undertaking when using rig-operated straddle packers with pressure testing. However, this established technique has limited effectiveness because it does not necessarily address the overall comprehensive integrity of the entire completion, which might include additional intervals of serious corrosion leading to leaks in the near future.We examined the results of low-frequency electromagnetic (EM) remote frequency eddy current (RFEC) wireline logs from over 80 wells in one mature Middle Eastern offshore field, profiling the severity of measured metal loss (ML) from concentric casings against proven rig-discovered leaks and rigless measurements of subsurface ML. Casing leaks that otherwise would have been detected only by conventional zonal pressure testing from a workover rig can now be located and forecasted with a high degree of probability when using this evaluation tool.The importance of maintaining oilfield casing integrity for safety, environmental, and flow assurance objectives, combined with the high costs of drilling new wells, creates a necessity for this integrated well integrity appraisal approach. Application of this EM logging technology to identify intervals of external ML has great significance in being able to anticipate casing intervals with high likelihood of failure due to invasive corrosion.

TX 75083-3836 U.S.A., fax 01-972-952-9435. AbstractThis paper presents the results of an investigation concerning the development of a reliable and accurate technique for establishing the stabilized deliverability performance of multi-layer commingled systems using multirate production log measurements. Both linear and non-linear systems are addressed in this paper, providing a basis for the analysis of reservoirs exhibiting Darcy and non-Darcy flow, respectively.Extension of the conventional Selective Inflow Performance analysis is also presented in this paper to obtain estimates of the formation and well completion properties such as effective permeability, radial flow steady state damage /stimulation skin effect, and non-Darcy flow coefficient. In the specific case where the deliverability performance of a vertically fractured well is considered, estimates of the effective fracture half-length and average fracture conductivity may be derived from the analysis. In cases where the multirate deliverability tests are performed under boundary dominated flow conditions, conventional deliverability analysis techniques may also be employed to derive estimates of the reservoir drainage area in addition to the well and reservoir parameters that can be obtained in a transient flow analysis. Applications of the analyses reported in this paper demonstrate the use of the analyses to evaluate the inflow performance measurements of commingled multi-layer reservoirs obtained using multi-rate production logs.

This paper presents the results of an investigation involving the development of a reliable and accurate methodology for establishing the stabilized deliverability performance of multi-layer commingled reservoir systems using multi-rate production log measurements. Both linear and non-linear systems are considered in this work, providing a basis for the analysis of reservoirs that exhibit Darcy and non-Darcy flow, respectively. An extension of the conventional Selective Inflow Performance analysis is presented in this paper to obtain estimates of the formation and well completion properties such as effective permeability, radial flow steady state damage /stimulation skin effect, and non-Darcy flow coefficient. In the specific case where the deliverability performance of a vertically fractured well is considered, estimates of the effective fracture half-length and average fracture conductivity may be derived from the analysis. In cases where the multi-rate deliverability measurements are obtained under boundary dominated flow conditions, conventional deliverability analysis techniques may also be employed to derive estimates of the reservoir drainage area in addition to the well and reservoir parameters that can be obtained in a transient flow analysis. Applications of the analyses reported in this paper demonstrate the use of the analyses for evaluation of the inflow performance of commingled multi-layer reservoirs using multi-rate production log measurements. Introduction The analysis of the effect of a variable flow rate production history on the pressure transient performance of a well under Darcy flow conditions has conventionally been accomplished using the convolution of the varying flow rate and pressure history of the well to evaluate the transient performance. This relationship is presented in integral form in Eq. 1 and has been utilized for quite a long time1 in the analysis of the transient pressure behavior of oil and gas wells. Equation (1) The dimensionless wellbore pressure at any point in time (tD) is shown to be a direct function of the varying flow rate and pressure history of the well prior to that point in time. The integral relationship given in Eq. 1 can be readily evaluated as a summation of discrete intervals of time for which the flow rate history is assumed to be piece-wise continuous, as a series of constant flow rate steps. This concept is expressed mathematically with Eq. 2 and has commonly been used as the basis for correlating the effects of a variable flow rate history on the pressure transient behavior of a well with the solution for a constant flow rate inner boundary condition. Equation (2) The definitions of the dimensionless variables used in this superposition relationship are given in terms of consistent units for slightly-compressible liquid flow analyses with Eqs. 3 through 5 for time, flow rate, and wellbore pressure, respectively. In the case of an unfractured vertical well, the system characteristic length (Lc) is equal to the wellbore radius (rw).