Horse Hill Developments Ltd
Horse Hill-1 (LR/24-4)
Extended Well Test Application - Supplemental Information
Per our WONS extended well testing (EWT) application, Horse Hill Developments Ltd (HHDL) is
seeking OGA’s consent for a further EWT of the Horse Hill-1 (HH-1) well. This document provides
supplemental information, namely:
- HH-1 test intervals, Portland test programme, Kimmeridge Limestone(s) test
programme and testing operations sequence.
Test Programme Objectives
The primary objective of each of three tests is to establish that a minimum commercial volume of
oil in place (OIP) is connected to each of three previously tested oil pools. To estimate connected
OIP volumes a measurable pressure drop under steady state flow conditions must be achieved.
Currently the plan aims to achieve a pressure drop of around 10-15 psi, i.e. large enough to be
unambiguous but small enough to avoid dropping below the bubble point pressure to avoid free
gas within the reservoir that may complicate any estimate of total system compressibility. The
steady state pressure drop therefore requires a minimum volume of oil to be produced.
It should be noted that in order to obtain steady state flow conditions the well will be significantly
choked back to below the flow rate that could be achieved during future sustainable production.
The tests and outline flow rates are designed to minimise the amount of free gas in the system of
each oil pool, i.e. keep the area surrounding the well bore above bubble point pressure.
Base Case Test Sequence
The overall base case testing programme, consist of 3 separate tests of three “independent”
reservoirs/oil pools, namely:
- Test 1: Portland Sandstone conventional reservoir
- Test 2: Kimmeridge Limestone 4 - naturally fractured reservoir
- Test 3: Kimmeridge Limestone 3 - naturally fractured reservoir
Table 1 below shows the base case test intervals:
Table 1: HH-1 Well Test Intervals
Test 1 Portland
Test 2 KL4
Test 3 KL3
- Can KL3 and KL4 be commingled as one zone? If so, what is a sustainable flow rate?
- Why is there a difference in PI between KL3 and KL4 zones? Is it that KL4 was cleaned
up via acidisation, or that KL3 was damaged due to longer acid residency?
Each KL test will follow the concept and methodology, below:
Table 3 below, illustrates the current outline testing sequence, flow rates, shut in periods and
associated durations. It should be noted that this is an outline plan and may be modified
dependent on the data gathered from the initial two short duration flow and shut in periods.
Table 3: Outline KL3 and KL4 Test Sequence
KL3 and KL4 zones - *PER* ZONE TEST PLAN - PLUS Potential Additional Co-mingled Flow.
Rate - bopd
Duration - hours
Cum. Production - bbo
Get initial pressure
Downhole gauges may be left in place as part of the well-suspension programme – this will be
decided towards the end of the sequence of tests. The aim of such monitoring
is to understand gravitational effects to help refine estimates of System Compressibility and
possible interference testing with regional KL wells e.g. Broadford Bridge-1, Brockham, Balcombe.
Dependent on achieving the primary testing objectives within the time allowed under planning
consent, one or more short duration contingent tests may be undertaken to include one or more
of the following zones:
- Test 4: a commingled test of KL3 and KL4. If sufficient time we plan to produce from
one KL completion zone and monitor the pressure in the other completion zone
- Test 5: a new short duration test of the previously untested deeper KL2 and or KL1
zones, similar in duration/scope to the early Portland/KL3 and KL4 flow periods
Base Case Extended Well Test Operations Sequence:
Figure 1, below illustrates the current status of HH-1, i.e. as left following well testing in 2016.
Note that the test zones are as labelled in 2016. The Portland is test zone 3, KL4 test encompasses
zones 2/2a and KL3 zone 1.
Kimmeridge Limestone test operations (for each of KL3 and KL4):
Depending on the results of the flow tests, a decision will be made on whether to run a dedicated
Additional works may include: