The optimal semi-analytical modeling for the infinite-conductivity horizontal well performance under rectangular bounded reservoir based on a new instantaneous source function

The main objective of this study is to develop the optimal semi-analytical modeling for the infiniteconductivity horizontal well performance under rectangular bounded reservoir based on a new instantaneous source function.The available semi-analytical infinite-conductivity models(ICMs)for horizontal well under rectangular bounded reservoir in literature were developed by applying superposition of pressures in space(SPS).A new instantaneous source function(i.e.,instantaneous uniform-flux segmentary source function under bounded reservoir)is derived to be used instead of SPS to develop the optimal semi-analytical ICM.The new semi-analytical ICM is verified with ICM of Schlumberger[1]and with previous semi-analytical ICMs in terms of bottom hole pressure(BHP)profile and inflow rate distribution along the wellbore.The model is also validated with real horizontal wells in terms of inflow rate distribution along the wellbore.The results show that the developed model gives the optimal semi-analytical modeling for the infinite-conductivity horizontal well performance under rectangular bounded reservoir.Besides that,high computationalefficiency and high-resolution of wellbore discretization have been achieved(i.e.,wellbore segment number could be tens of hundreds depending on solution requirement).The results also show that at pseudosteady state(PSS)flow regime,inflow rate distribution along the wellbore by previous semi-analytical ICMs is stabilized U-shaped as performance of inflow rate distribution at late radial flow regime.Therefore,the previous semi-analytical ICMs are incorrectly modeling inflow rate distribution at PSS flow regime due to the negative influence of applying SPS.The optimal semi-analytical ICM is in a general form and real time domain,and can be applicable for 3D horizontal well and 2D vertical fracture well under infinite and rectangular bounded reservoirs,of uniform-flux and infinite-conductivity wellbore conditions at any time of well life.

Production data-based facies analysis for well placement in thinlayered reservoir

The exploitation of a thin-layered reservoir with thickness less than 5 m(16 ft)needs to rely upon sedimentary facies analysis,due to the low resolution of seismic data and sparse well data.However,the ambiguity of facies interpretation creates uncertainty in facies and reservoir mapping.The study aims to better define facies distribution,predict sand-body architecture,and consequently reduce risks in planning development wells,by integrating production data(dynamic)with conceptual geological models(static).An example is shown from the M1 Member of the Napo Formation in the B and G Oilfields(Block J),Oriente Basin,Ecuador.The M1 reservoir is a thin-layered sandstone reservoir below seismic resolution.Core and well-log facies interpretation indicates depositional facies of a tidedominated estuary.Production data during the water injection phase of field development can delineate the detailed geometry of the sand bodies.The injector-producer rate responses can determine the connectivity of sand bodies.Well performance during primary recovery can capture the scale of single reservoirs because the initial production rates and the cumulative oil production of individual wells are generally proportional to the size of sand bodies.A facies model was thereby generated.Two step-out wells were planned using this model and drilled successfully.The results demonstrate that the integration of dynamic and static data is critical to understanding reservoir facies distribution.

hale gas reservoir modeling and production evaluation considering complex gas transport mechanisms and dispersed distribution of kerogen

Stimulated shale reservoirs consist of kerogen,inorganic matter,secondary and hydraulic fractures.The dispersed distribution of kerogen within matrices and complex gas flow mechanisms make production evaluation challenging.Here we establish an analytical method that addresses kerogen-inorganic matter gas transfer,dispersed kerogen distribution,and complex gas flow mechanisms to facilitate evaluating gas production.The matrix element is defined as a kerogen core with an exterior inorganic sphere.Unlike most previous models,we merely use boundary conditions to describe kerogen-inorganic matter gas transfer without the instantaneous kerogen gas source term.It is closer to real inter-porosity flow conditions between kerogen and inorganic matter.Knudsen diffusion,surface diffusion,adsorption/desorption,and slip corrected flow are involved in matrix gas flow.Matrix-fracture coupling is realized by using a seven-region linear flow model.The model is verified against a published model and field data.Results reveal that inorganic matrices serve as a major gas source especially at early times.Kerogen provides limited contributions to production even under a pseudo-steady state.Kerogen properties’influence starts from the late matrix-fracture inter-porosity flow regime,while inorganic matter properties control almost all flow regimes except the early-mid time fracture linear flow regime.The contribution of different linear flow regions is also documented.

Lean HC gas injection pilots analysis and IPR back calculation to examine the impact of asphaltene deposition on flow performance

Gas injection is one of the most economical and effective approach to improve oil recovery.However,outcome of such approach is contingent to reservoir heterogeneities impacting gas override and fingering.Furthermore,injected fluid composition and its compatibility with the reservoir fluid potentially impact flow assurance issues such as asphaltene precipitation into the wellbore and surface facilities.The objective of this paper is to examine the lesson learnt from a couple of field scale 5 spot patterned lean hydrocarbon gas injection pilots which were deployed in a heterogeneous carbonate formation of a giant field located offshore Abu Dhabi under secondary and tertiary drive mechanisms.Said pilots provides a valuable insight on production performance,pressure support,gravity override,fluid composition and evidence of asphaltene deposition that resulted in heavy production loss prior to the solvent treatment.This paper presents the overall pilot performance including pattern recovery,fluid front movement,potential role of heterogeneity in gas breakthrough timings and the operational events to witness asphaltene deposition affecting the flow performance.The deposited asphaltene cake thickness was measured mechanically during routine tubing clearance check operation that was helpful in estimating production loss due to altered production tubing flow opening.Also an integrated approach is applied to confirm the AOP laboratory measurements with the actual deposits of asphaltene that were found in to the production tubing.In order to confirm the effect of asphaltene deposition on inflow from near wellbore formation to the wellbore,a straightforward yet innovative nodal analysis approach was applied to study well performance using the calibrated and history matched well model.It was noticed that not only the outflow was altered because of asphaltene deposition into wellbore but also the inflow(productivity index)was seriously impacted potentially due to asphaltene deposition in near wellbore formation.