A Breakthrough in ESP Implementation to Solve Extreme Well Problems

Abstract

Electrical Submersible Pump (ESP) is an artificial lift that often associated with big production rate. To be able to install ESP, a well should have at least 300 bfpd production rate. ESP well candidates must also have very small amount of base sediment (BS) and quite low GOR, which means ESP does not suit wells with unconsolidated sand reservoir and also high GOR wells. As technology flourished, these requirements for an ESP well are no longer valid. A breakthrough was established for ESP implementation. Nowadays there are some ESP that can withstand extreme well problems such as unconsolidated sand reservoir, high GOR, heavy oil, and slimhole casing.

These extreme wells exist quite a lot in Pertamina EP Asset 1 (PEP A1). JM Structure has unconsolidated sand reservoir with BS number 0.5-40%, NB Structure has heavy oil problem with 10-200 cp reservoir fluid viscosity, GS Structure has gassy problem with 2000 – 4000 scf/stb GOR, and JB Structure has slim hole problem with 4-1/2” casing. PEP A1 face quite challenging condition to produce wells from these structures optimally. This paper will cover Pertamina EP success in handling sand and high GOR problems.

ESP intended to solve sand problem has open impellers, which cause less probability of scale and solids deposition. This open impeller also creates no space between impeller and diffuser, hence no solids accumulation. This ESP is also able to operate in low rate condition, as low as 50 to 60 bfpd. Above 150 bfpd, ESP with conventional type of impellers but with abrasive resistant  material is used. To handle high GOR problem, multiphase pump (MPP) is used along with gas separator. MPP stage design has axial screw type impeller and gas handling diffuser. Gas from reservoir fluid will be compressed and be broken into smaller bubbles resulting in homogenous gas-liquid mixture, hence no gas lock during production. Pertamina EP has successfully installed both ESP types in JM and GS structure with sight to install ESP for heavy oil and slim hole casing in the near future.

ESP for sand problem were installed in well JM-134 (open impeller) with 10% - 50% BS and JM-25 (abrasive resistant material) with production rate around 600 bfpd of JM Structure. ESP for high GOR were installed in well GS-1 and GS-15 of GS Structure. Both wells has around 2000 scf/stb GOR. In total, these four wells have been producing 4706 bbls and counting. It shows that these two types of ESP have successfully handled sand and high GOR problems in PEP A1.

The successful implementation these two types ESP shows that a breakthrough has been made in ESP implementation, which makes old stereotypes about ESP well that were mentioned above are now obsolete.