Estimation of Surface Production Rates in Electrical Submersible Pump Producing Oil Wells by Numerical Iterative Algorithm-Based Models
Authors: Varma Nakul , Manish Kumar , Chandak Ravi , Chauhan Shailesh , Singhal Joy , Bohra Avinash 
Published: October 2023

This paper is an addendum to SPE-200174-MS, which explains the deterministic Approach Towards Well Intervention Candidate Selection & quantification of Parameters in ESP & Jet Pump Wells. The purpose of this paper is to quantify liquid rates in ESP producer wells by estimating the hidden parameter which directly impacts the system production rates. These hidden parameters are the tubing inner wall deposition, deposition inside pumps leading to pump head reduction. These hidden variables make simple well modelling software production rate calculations incorrect. This paper describes facts related to the verification of the output model liquid rates with genuinely observed rates by surface well test units and calibrated multiphase flow meter which makes the overall modelling valid and correct.

In ESP wells, the input parameters required by the model is pump intake pressure, pump discharge pressure, pump running frequency and surface THP which are generally available. The models described in SPE-200174-MS for ESP & Jet pump wells can compute 3 variables for 3 set of equations. This model gives surface liquid rates, tubing wall deposition, ESP pump wear (deposition inside pump). Other input parameters required in the model to run the iterations are well water cut, GOR (Gas to oil ratio), productivity index, and reservoir pressure.

These models calculate surface production rates for well rates allocation & support in monitoring various wells performance. Its results have been verified by various surface well test units & calibrated multiphase flow meters. There are many advantages of this algorithm such as - Prediction & calibration of MPFMs (Multiphase flow meter data) at well pads, tubing deposition estimation (assists in planning of tubing scraping jobs by slickline unit, Coil tubing roto-jet wellbore cleanout or motor assisted scraper jobs in flowing well), ESP pumps wear estimation (assist in planning ESP wear treatment by chemical soaking/mechanical flushing operations).

This paper gives a new approach for ESP wells production rates determination. It mentions various factors which affects the liquid rate of wells. Production restoration candidates are very easily identified using this model. This can be very useful where well testing frequency is less, well pad MPFM is not installed, or where there are frequent issues in MPFM.

This work assists in determining various important parameters to monitor oil producer wells with electric submersible pump (ESP). The problems are associated to the fields that contain medium gravity viscous crude (10-40cp) in high permeability (1-5 Darcy) sands. It was observed that formation oil to water flooding had adverse mobility ratio and improve sweep efficiency, polymer flooding was adopted. As the Polymer flooding proceeded, polymer breakthrough in producer wells was observed. The major challenges faced in producer wells are polymer & scale depositions. This issue has surfaced in field due to polymer breakthrough in oil producers and mixing of produced polymer concentration in well fluid with scales, wax, or other bivalent ions. Major concerns due to polymer deposition included, fouling of artificial lift system, decrease of well uptime, ESP efficiency decrease. ESP is the major artificial lifts for the field, the surface liquid rate is one of the most important parameters which can address production decrease which may have been caused by any reason. Thus, a necessity was felt to address the issue by empirical based modelling which can quantify the same. The developed models are helpful and determines various surface liquid rate and other critical causal parameters in ESP well.